Oxidation process

Abstract

The present invention relates to a method for producing chlorine dioxide from chlorite in the presence of a complex containing iron ions or manganese ions, compositions and kits suitable for such a method and methods for treating water or substrates with such compositions.

Description

Technical Field

[0001] This invention relates to a method for generating chlorine dioxide from chlorite in the presence of a complex containing iron or manganese ions, a method for treating a substrate with a chlorine-containing oxidant in the presence of a complex containing iron or manganese ions, and related aqueous media, kits, and compositions. Background Technology

[0002] Chlorine dioxide functions as an oxidant in a variety of applications, such as disinfection of (surface) water and removal of manganese and iron metals from (surface) water via oxides that form them, treatment of industrial water (e.g., in cooling towers), taste and odor control, and bleaching of cellulose matrices (especially wood pulp). In addition to its important uses in these applications, chlorine dioxide is also used in food processing, such as for washing fruits and vegetables, cleaning animal processing equipment and animal carcasses, and treating livestock habitats.

[0003] Chlorine dioxide is used as a highly selective oxidant due to its unique single-electron transfer mechanism in which it is reduced to chlorite (see Alternative Disinfectants and Oxidants Guidance Manual, United States Environmental Protection Agency, 1999 (www.epa.gov / ogwdw / mdbp / alternative_disinfectants_guidance.pdf), especially its Chapter 4 (“Chlorine Dioxide”)).

[0004] Chlorine dioxide is widely used in wood pulp bleaching and water treatment, especially the latter due to its antimicrobial activity, as it causes severe physical damage to bacterial cells and viral capsids. Chlorine dioxide is at least as effective as elemental chlorine, exhibiting 2-4 log inactivation when used at concentrations of a few mg / L.

[0005] A wide variety of transition metal-based bleaching complexes have been investigated to enhance the bleaching or delignifying activity of hydrogen peroxide on wood pulp. For example, binuclear manganese complexes based on triazacyclononane ligands are known to be particularly active complexes. These complexes activate hydrogen peroxide to bleach cellulose matrices, such as wood pulp or raw cotton (see, for example, EP 0 458 397A2 (Unilever NV and Unilever plc), WO 2006 / 125517 A1 (Unilever plc et al.), US 2001 / 0025695 A1 (Patt et al.), WO 2011 / 128649 (Unilever plc et al.) and WO 2011 / 141692 (Unilever plc et al.)). For a detailed review of different types of bleaching complexes that are active with hydrogen peroxide or hydrogen peroxide, see RHage and A Lienke, Angew. Chem., Int. Ed. Engl., 45, 206-222 (2006).

[0006] It has been described (see TP Umile & JT Groves’ Angew. Chem., Int. Ed. Engl., 50, 695-698 (2011), TP Umile, D Wang & JT Groves’ Inorg. Chem., 50, 10353-10362 (2011), WO 2012 / 027216 (The Trustees of Princeton University), and SD Hicks et al.’s Angew. Chem., Int. Ed. Engl., 50, 699-702 (2011)) that manganese complexes of porphyrins and porphyrazines can catalyze the formation of chlorine dioxide from sodium chlorite (in phosphate buffer pH 6.8-7.0 or acetate buffer pH 4.5-5.1). In 2014, SD Hicks et al. (J. Am. Chem. Soc., 136, 3680-3686 (2014)) described the use of pentadentate N,N-bis(pyridin-2-ylmethyl)bis(pyridin-2-yl)methylamine (N4Py) and N-benzyl-N,N',N'-tris(pyridin-2-ylmethyl)-1,2,-diaminoethane (Bn-TPEN) manganese complexes in acetate buffer at pH 5.0 in the chlorite-catalyzed formation of chlorine dioxide.

[0007] P. Barman et al. (Inorg. Chem., 55, 10170-10181 (2016)) have investigated the ability of iron complexes based on N4py and two bispidone ligands ((2,4-di-(2-pyridyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate and (2,4-di-(2-pyridyl)-7-methyl-3-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate) to accelerate the formation of chlorine dioxide from chlorite in acetate buffer at pH 5.0. TB. Champ et al. (Inorg. Chem., 60, 2905-2910) A different approach is reported in (2021), in which Mn complexes and Fe complexes based on substituted bisphenol glycine are reacted with chlorite and peracetic acid at pH 4.0 to produce chlorine dioxide.

[0008] Various iron and manganese complexes are described in WO 2016 / 198891 A1 and WO 2016 / 198890 A1 (both belonging to Chemsenti Ltd.). Specific examples of iron and manganese complexes include the accelerated production of chlorine dioxide from chlorite in an aqueous solution containing an acetate buffer at pH 5.0. A particular catalyst has been shown to be active at high pH levels (up to pH 11.0).

[0009] Although it is known that chlorite can be catalytically decomposed into chlorine dioxide, chlorate and a variety of other species by iron salts (see, for example, I Fábián’s Coord. Chem. Rev., 216-217, 449-472 (2001)), porphyrin-based iron complexes have been shown to disproportionate chlorite into chlorate and chloride anions without forming chlorine dioxide, compared to manganese-containing analogs (see MJ Zdilla et al. (Inorg. Chem., 48, 2260-2268 (2009))).

[0010] Publications on porphyrins, porphyrinazines, N4py, manganese complexes of Bn-TPEN, and iron complexes of pentadentate bispidon ligands have proposed alternative routes for the production of chlorine dioxide from chlorite without the use of chlorate and reducing agents. The latter method is the most common approach for large-scale chlorine dioxide production, such as in pulp bleaching plants. For small-scale chlorine dioxide production, a chemical oxidant (elemental chlorine, or hypochlorite + HCl) is typically added to a chlorite solution, followed by acidification of the chlorite with HCl, or an electrochemical oxidation step.

[0011] No indication was found in the aforementioned patents or academic literature that the formation of chlorine dioxide from chlorite could be significantly higher at low pH levels in the presence of a catalyst compared to the higher pH levels described in the art.

[0012] For safety reasons, it is undesirable to produce chlorine dioxide in a chemical plant, then store and transport it to where it is consumed, such as in a pulp mill or water treatment facility. Therefore, chlorine dioxide is typically produced near its point of use by reacting sodium chlorate with an acid such as sulfuric acid and a reducing agent such as hydrogen peroxide, sulfur dioxide, or methanol. In pulp processing, for example, the resulting gaseous chlorine dioxide is then taken to another container, captured in water, and used as is to treat the pulp stock.

[0013] Other known methods for producing chlorine dioxide from chlorite include acidification with hypochlorous acid or sulfuric acid, oxidation of chlorite with, for example, chlorine, or electrochemical methods. Such methods are typically used for small-scale production of chlorine dioxide (e.g., in small facilities delivering chlorine dioxide for hygiene / antimicrobial applications).

[0014] Although chlorine dioxide has significant benefits and is used in a variety of applications, it would be advantageous in the field to improve and / or develop alternative methods for producing this chemical from chlorite in acidic media. This invention addresses this need. Summary of the Invention

[0015] Under acidic conditions (e.g., solutions from about pH 1 to about pH 3.5), those skilled in the art would expect irreversible degradation of manganese or iron complexes due to the increased likelihood of protonation of the chelating atoms of the stabilizing ligands, thereby preventing and stabilizing these ligands by binding to manganese or iron ions. However, the inventors have discovered that iron and manganese complexes containing various polydentate nitrogen donor ligands exhibit surprising activity in accelerating the formation of chlorine dioxide from chlorite under acidic conditions containing bisulfate or oxalate buffers.

[0016] Therefore, from a first aspect, the present invention provides a method for producing chlorine dioxide from chlorite, the method comprising: contacting the following in an aqueous medium:

[0017] (i) chlorite; and

[0018] (ii) A complex comprising one or more iron ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one iron ion via at least three nitrogen atoms, provided that the one or more polydentate ligands are not porphyrin or porphyrinazine ligands; or

[0019] A complex comprising one or more manganese ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one manganese ion by at least three nitrogen atoms.

[0020] The aqueous medium contains a bisulfate or oxalate buffer and has a pH of about 1 to about 3.5.

[0021] From a second aspect, the present invention provides a composition comprising:

[0022] (i) An aqueous medium comprising a bisulfate or oxalate buffer and having a pH of about 1 to about 3.5;

[0023] (ii) Chlorite; and

[0024] (iii) A complex comprising one or more iron ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one iron ion via at least three nitrogen atoms, provided that the one or more polydentate ligands are not porphyrin or porphyrinazine ligands; or

[0025] A complex comprising one or more manganese ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one manganese ion by at least three nitrogen atoms.

[0026] From a third aspect, the present invention provides a method for treating water or a matrix, the method comprising: contacting the water or matrix with the composition defined in the second aspect.

[0027] From a fourth aspect, the present invention provides a solid composition comprising:

[0028] (i) A solid acid comprising a hydrogen sulfate or an oxalate, and having a pKa of about 1 to about 3.5 in water at 25°C;

[0029] (ii) Chlorite; and

[0030] (iii) A complex comprising one or more iron ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one iron ion via at least three nitrogen atoms, provided that the one or more polydentate ligands are not porphyrin or porphyrinazine ligands; or

[0031] A complex comprising one or more manganese ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one manganese ion by at least three nitrogen atoms.

[0032] From a fifth aspect, the present invention provides a composition comprising: a chlorite, an acid comprising a bisulfate or oxalate and having a pKa of about 1 to about 3.5 in water at 25°C, and one or more polydentate ligands, said polydentate ligands being chelating agents capable of chelating at least one iron or manganese ion by at least three nitrogen atoms. In some embodiments, said one or more polydentate ligands are not porphyrin or porphyrinazine ligands.

[0033] From a sixth aspect, the present invention provides a kit comprising the following items as separate components:

[0034] (i) Chlorite;

[0035] (ii) an acid comprising a hydrogen sulfate or oxalate, and having a pKa of about 1 to about 3.5 in water at 25°C; and

[0036] (iii) One or more polydentate ligands, said polydentate ligands being chelating agents capable of chelating at least one iron or manganese ion by at least three nitrogen atoms.

[0037] From a seventh aspect, the present invention provides a kit comprising the following separate items:

[0038] (i) Chlorite;

[0039] (ii) an acid comprising a hydrogen sulfate or oxalate and having a pKa of about 1 to about 3.5 in water at 25°C; and any one of (iii) and (iv) below:

[0040] (iii) A complex comprising one or more iron ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one iron ion via at least three nitrogen atoms, provided that the one or more polydentate ligands are not porphyrin or porphyrinazine ligands; or

[0041] (iv) A complex comprising one or more manganese ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one manganese ion by at least three nitrogen atoms.

[0042] The use of chlorite in the context of wood pulp bleaching and / or delignification according to the present invention relates to the use of iron- or manganese-containing complexes as described herein under acidic conditions, allowing for better and / or more flexible use of these chemicals and providing an alternative to existing methods. However, the present invention is not limited to the treatment of wood pulp. Other matrices (including cellulose matrices such as raw cotton or stained cotton garments) can be treated according to the present invention, for example, with detergents or other formulations containing chlorite and the complexes or polydentate ligands described herein. Such formulations can be used in cleaning and hygienic methods in place of formulations containing more conventional peroxide bleaching agents. As discussed in more detail below, the present invention is also used for water treatment, for example, to mitigate microbial contamination, and other applications in which the antimicrobial effect of chlorine dioxide is beneficial.

[0043] Furthermore, this invention allows for modifications (e.g., improvements) to existing uses of chlorite under acidic conditions, such as allowing for lower temperatures or shorter durations of use. Additionally, smaller doses of chlorite can be used, for example, to achieve antimicrobial activity, compared to use in the absence of the iron or manganese complexes described herein. Another advantage of this invention is that, for example, solid chlorite bound to an iron or manganese complex and an acid can be used for antimicrobial applications without the need for offline (i.e., ex situ) generation of chlorine dioxide.

[0044] Therefore, the present invention allows for modifications (e.g., improvements) to existing methods for forming chlorine dioxide from chlorite in acidic media.

[0045] Other aspects and embodiments of the invention will become apparent from the following discussion. Detailed Implementation

[0046] As outlined above, the present invention is based on the discovery that complexes comprising one or more iron ions and one or more polydentate ligands (the polydentate ligands being chelating agents capable of chelating at least one iron ion by at least three nitrogen atoms, provided that the one or more polydentate ligands are not porphyrin or porphyrinazine ligands), or complexes comprising one or more manganese ions and one or more polydentate ligands (the polydentate ligands being chelating agents capable of chelating at least one manganese ion by at least three nitrogen atoms), can accelerate the conversion of chlorite to chlorine dioxide in acidic solutions buffered with bisulfate or oxalate buffers at a pH of about 1 to about 3.5, and thereby provide improvements or alternatives to existing methods and compositions for the production of chlorine dioxide from chlorite.

[0047] The methods of the first and third aspects of the invention relate to the use of an aqueous medium with a pH of about 1 to about 3.5, and the composition of the second aspect of the invention comprises an aqueous medium with a pH of about 1 to about 3.5, said aqueous medium typically having at least 1% by weight of water, meaning that the aqueous liquid constituting the liquid aqueous medium contains at least 1% by weight of water, more typically at least 10% by weight, even more typically 25% by weight, and most typically at least 50% by weight of water. Typically, the aqueous medium will be a solution (i.e., in which its various components, such as one or more chlorites, acids, and iron or manganese complexes, are dissolved). Although less typical, other aqueous (i.e., aqueous) media (including slurries and suspensions) may also be used as said aqueous medium. The aqueous medium comprises a continuous liquid phase in which the liquid component is primarily water (i.e., 50 to 100% by weight of water, typically 80 to 100% by weight of water). Depending on the actual or intended use of the aqueous medium described herein, the liquid balance in the aqueous medium that is not water (if present) can be any convenient liquid, such as a liquid alcohol, such as C 1-4 Alcohols such as methanol or ethanol. In their presence, the other liquid will typically be water-miscible. Although the continuous liquid phase is usually entirely water, it should be understood that this does not preclude the presence of small amounts of other liquids (e.g., in amounts less than about 10% by weight, more typically less than about 5% by weight), for example, as contaminants in other materials that bring the continuous liquid phase into contact with it.

[0048] The aqueous medium described herein has a liquid pH of about 1 to about 3.5. According to some embodiments, the pH is about 1.5 to about 3.0, such as about 2 to about 2.5. Solutions or other systems having this pH can be readily prepared by those skilled in the art. For example, those skilled in the art will recognize that a suitable buffer will allow control over the desired pH, and the selection of a suitable buffer (other than bisulfate and / or oxalate buffers) is within the normal capabilities of those skilled in the art. The desired pH of the aqueous medium can be achieved by adding an appropriate amount of acid. This can be a solid acid, such as a solid acid with a pKa of about 1 to about 3.5 in water at 25°C. The aqueous medium contains a bisulfate or oxalate buffer, which can be present by adding, for example, sodium bisulfate, potassium bisulfate, or oxalic acid. Alternatively, the acid can be first dissolved in an appropriate amount of water or other suitable liquid, and the resulting composition can then be added to a composition containing chlorite and an iron or manganese complex. Alternatively, the acid in liquid form can be added to a composition containing chlorite and an iron or manganese complex. The acid can be used in a form obtained from the chemical supplier, or it can be diluted in an aqueous medium before use. The pH of an aqueous medium containing an iron or manganese complex, chlorite, and acid can be determined immediately after mixing these components. With the generation of chlorine dioxide from the chlorite, the pH of the aqueous medium can rise above 3.

[0049] Suitable acids include those with pKa values ​​of approximately 3.5 or lower. To avoid ambiguity, the pKa values ​​used in this article refer to those for the reaction AH. H + + A - The determination was performed in water at 25°C, where AH represents an acid, and A... - This refers to the conjugate base, as described in the Dissociation Constants of Organic Acids and Bases and the Dissociation Constants of Inorganic Acids and Bases in the 91st edition of the CRC Handbook of Chemistry and Physics (2010), and in the references cited therein. Therefore, when the acid used is, for example, hydrogen sulfate ([HSO4]),... - In the case of conjugate base A, - It is sulfate ([SO4]). 2- When the acid used is, for example, hydrochloric acid (HCl), the conjugate base is chloride ions (Cl-). -To further avoid ambiguity, as is generally accepted in the art, the pKa in water at 25°C is defined herein as 14.0.

[0050] Suitable acids include sodium bisulfate, potassium bisulfate, sulfuric acid, hydrochloric acid, oxalic acid, and hydrobromic acid. For the avoidance of doubt, aqueous media may contain bisulfate or oxalate buffers (which can be provided by adding sodium bisulfate, potassium bisulfate, or oxalic acid) and may also contain other acids such as sulfuric acid, hydrochloric acid, and / or hydrobromic acid.

[0051] In some embodiments, the aqueous medium comprises a bisulfate buffer. In some embodiments, the aqueous medium comprises one or more acids selected from sodium bisulfate, potassium bisulfate, and hydrochloric acid. Typically, the aqueous medium comprises one such acid. In some embodiments, the aqueous medium comprises an acid selected from sodium bisulfate and potassium bisulfate, and also comprises hydrochloric acid.

[0052] The chlorites used according to various aspects of the invention are typically inorganic chlorites, the properties of which are not critical to the operation of the invention. One or more chlorites may be used in any given method, but typically only one chlorite will be used. Non-limiting examples of chlorites that may be used include sodium chlorite (NaClO2), potassium chlorite (KClO2), lithium chlorite (LiClO2), calcium chlorite (Ca(ClO2)2), barium chlorite (Ba(ClO2)2), and magnesium chlorite (Mg(ClO2)2). Typically, sodium chlorite or potassium chlorite is used. More typically, the chlorite used is sodium chlorite.

[0053] As described above, the method according to the first aspect of the invention comprises contacting a chlorite with a complex comprising one or more iron or manganese ions and one or more polydentate ligands (as defined herein) in an aqueous medium having a pH of about 1 to about 3.5. It should be understood that the contact can be achieved in a variety of ways. For example, an aqueous medium can be prepared to which the chlorite and the metal complex are added alone or in combination. The chlorite can be added as a solid (e.g., as a powder or granules) or as an optionally buffered solution in water. Similarly, the metal complex can be added alone as a solid (e.g., as a powder, crystalline granules) or, for example, after dilution with a salt. Alternatively, it can be added as an optionally buffered solution in water or as a solution in an alternative solvent such as an alcohol. In the case of addition as a solution, the solution is typically formed by dissolving the iron or manganese complex in (optionally buffered) water. Typically, the chlorite is dissolved in an aqueous liquid, followed by the addition of an acid to achieve the desired pH. Iron or manganese complexes can be added as solids or solutions at any stage, but typically they will be added to an aqueous medium that already contains chlorite and / or acid.

[0054] Other arrangements are also possible and can be readily conceived by those skilled in the art. For example, iron or manganese complexes can be added in situ: iron or manganese ions may be present in the aqueous liquid or may be added to the aqueous liquid, and iron or manganese complexes may be formed in situ by adding appropriate ligands. For example, untreated tap water may contain sufficient amounts of iron or manganese ions to produce usable amounts of the iron or manganese complexes described herein by adding appropriate amounts of the polydentate ligands described herein in situ.

[0055] Alternatively, according to the fifth and sixth aspects of the invention, a composition or kit comprising a polydentate ligand as defined herein, a chlorite, and an acid (containing a bisulfate or oxalate and having a pKa of about 1 to about 3.5 in water at 25°C) can be provided, from which compositions according to the second aspect of the invention can be prepared. Although the polydentate ligand in the composition of the second aspect is part of an iron or manganese complex, it should be understood from the preceding paragraphs that it is not necessary to prepare the composition by introducing the iron or manganese complex as is, since the iron or manganese complex can be prepared in situ by providing a suitable source of iron or manganese ions. For the avoidance of doubt, the polydentate ligand in the kit can initially be reacted with an iron or manganese salt to form the corresponding iron or manganese complex, which may (or may not) be separated before contact with the chlorite and the polydentate ligand described herein.

[0056] To avoid ambiguity, when an acid is described as containing a bisulfate or oxalate, the acid includes these species as an anion having a charge stabilized by one or more counterions, or as an uncharged species bonded to one or more other parts, such as hydrogen atoms. For example, as defined herein, bisulfates are components in the range of sodium bisulfate and potassium bisulfate, and oxalates are components in the range of oxalic acid.

[0057] Alternatively, according to a fourth aspect of the invention, a solid composition comprising a solid acid (containing a bisulfate or oxalate and having a pKa of about 1 to about 3.5 in water at 25°C), a chlorite, and an iron or manganese complex can be provided, which can be combined with an aqueous solution to provide the composition of the second aspect. Similarly, and according to a seventh aspect, a kit comprising a chlorite, an acid containing a bisulfate or oxalate (which may be a solid acid and has a pKa of about 1 to about 3.5 in water at 25°C), and an iron or manganese complex can be provided, which can be combined with an aqueous solution to provide the composition of the second aspect.

[0058] When the acid is a solid acid, it can be selected from sodium bisulfate, potassium bisulfate, and oxalic acid. Chlorite can be as defined above, and is preferably sodium chlorite.

[0059] The weight ratio of the solid acid to chlorite and to the iron or manganese complex depends on the desired concentration of each component when combined with an aqueous solution (e.g., dissolved in an aqueous solution). Typically, the amount of iron or manganese complex is much lower than the amount of solid acid or chlorite, which can make precise feeding more difficult. Iron or manganese complexes are usually 'diluted' with fillers (e.g., in granular form), making it easier to achieve the correct amount of complex. Suitable fillers include sodium sulfate, sodium chloride, potassium chloride, potassium sulfate, magnesium sulfate, and calcium sulfate. Granulated materials include granules, which are asymmetric aggregates of powder particles. Granulation methods are well known in the art (see, for example, Shanmugam, Bioimpacts, 2015, 5(1), 55-63). Granular materials can be produced by wet granulation, dry granulation or compaction, and by melt solidification granulation. Granulation of solid compositions can improve the storage stability of iron or manganese complexes. This method of using iron or manganese complexes is well known in detergent formulations, particularly in laundry detergents and automatic dishwasher detergents. Non-limiting examples include WO95 / 06710 (Unilever NV), WO94 / 21777 (Unilever NV), WO2017 / 153528 (Conopco INC., Unilever), WO2010 / 115582 (Clariant International Ltd.), WO2014 / 198368 (Weylchem ​​Wiesbaden GmbH), WO2018 / 210442 (Weylchem ​​Wiesbaden GmbH), EP1913124B (Clariant, Produkte GmbH) and WO2011 / 005827 (Procterand Gamble Company).

[0060] The composition according to the first aspect of the invention can be added to a liquid medium to form a composition according to the second aspect of the invention, which can be used according to the first aspect of the invention.

[0061] Similarly, it should be understood that the kits according to the sixth or seventh aspect of the invention can also be used to form compositions according to the second aspect of the invention, which can be used according to the first aspect of the invention.

[0062] According to a particular embodiment, the kit of the present invention can take the form of a medicine box comprising separate compartments, such as the type described in WO 2012 / 027216 A1 (ibid.), which contains the components of the kit, namely chlorite, acid, and a multidentate ligand or an iron or manganese complex. For example, in a particular embodiment, the iron or manganese complex can be adsorbed (immobilized) on a solid carrier, thereby allowing chlorine dioxide to be generated by flowing water through the medicine box. Advantageously, it should be understood that, where the iron or manganese complex is immobilized in such a system, these can be reused after the chlorite is replaced.

[0063] Regardless of how the aqueous media of any aspect of the invention is prepared, one or more chlorites therein are typically present at a concentration of about 0.01 to about 100 mM (e.g., about 1 to about 50 mM). It will certainly be appreciated that those skilled in the art will be able to use appropriate concentrations of chlorites, as well as the concentrations / amounts of the other components described herein, without excessive burden.

[0064] In some embodiments, the aqueous medium of various aspects of the present invention comprises an alkali metal halide. The inventors have discovered that the presence of an alkali metal halide (such as sodium chloride) in the aqueous medium, along with iron or manganese complexes as defined herein, unexpectedly further accelerates the production of chlorine dioxide from chlorite. The alkali metal halide may comprise any alkali metal or halide. However, typically, the alkali metal is selected from sodium, potassium, and lithium, most typically sodium and potassium. The halide may be any of a chloride, fluoride, bromide, or iodide. Typically, the halide is a chloride. A mixture of different alkali metal halides may be present in the aqueous medium. However, typically, the alkali metal halide is sodium chloride.

[0065] The aqueous medium may contain about 10 mM to about 6 M of alkali metal halide. For example, the aqueous medium may contain about 15 mM to about 5 M, about 20 mM to about 4 M, about 25 mM to about 3 M, about 30 mM to about 2 M, about 35 mM to about 1 M, about 40 mM to about 0.8 M, or about 50 mM to about 0.6 M of alkali metal halide. Typically, the aqueous medium contains about 100 mM to about 1 M of alkali metal halide, such as about 100 mM to about 1 M of sodium chloride.

[0066] According to a specific implementation scheme, the complex contains one or more iron ions.

[0067] A chelating agent capable of chelating at least one iron or manganese ion via at least three nitrogen atoms means a polydentate ligand capable of chelating one or more iron or manganese ions by forming coordination bonds between three or more nitrogen atoms of the chelating agent and a common iron or manganese ion. In this context, and as is customary in the art, chelation requires that the nitrogen atoms of the chelating agent coordinate with the same transition metal ion (in this case, an iron or manganese ion). The chelating agent is therefore at least tridentate. When binding with an iron or manganese ion, the chelating agent can be tridentate, tetradentate, pentadentate, hexadentate, heptadentate, or octadentate, with tridentate, tetradentate, pentadentate, and hexadentate being the most common. Furthermore, some of the chelating agents described herein have a denticity greater than six (e.g., eight), where an octadentate ligand is capable of coordination via eight nitrogen atoms. However, when using these chelating agents, chelation is typically achieved by forming coordinate bonds between four nitrogen atoms and common iron or manganese ions: for example, in these octardate chelating agents, four of the eight nitrogen atoms can chelate to the first iron or manganese ion, and four of these nitrogen atoms can chelate to the second iron or manganese ion. This is typically achieved by octardate ligands whose structure has two parts that create two separate chelating regions, which are typically separated by a bridge, as explained and illustrated in more detail below with reference to specific polydentate ligands available according to the invention.

[0068] Typically, the chelating agents of the present invention capable of chelating at least one iron or manganese ion with at least three nitrogen atoms are chelating agents capable of chelating at least one iron or manganese ion with four, five, or six nitrogen atoms. To avoid ambiguity, although a chelating agent capable of chelating at least one iron or manganese ion with four nitrogen atoms may have a degree of chelation greater than four, such a chelating agent is not permitted to be chelated with five (or more) or three (or fewer) nitrogen atoms. Similarly, for example, a chelating agent capable of chelating at least one iron or manganese ion with three nitrogen atoms may have a degree of chelation greater than three, such a chelating agent is not permitted to be chelated with four (or more) or two (or fewer) nitrogen atoms, and so on.

[0069] It should be understood that chelating degree (and therefore the terms tridentate, tetradentate, pentadentate, hexadentate, heptadentate, or octadentate) refers to the number of donor atoms of a metal ion that can bind to it. Thus, a chelating agent, for example, with a tetradentate nitrogen donor, refers to an organic molecule containing four nitrogen atoms with lone pairs of electrons, which can bind to common transition metal ions (which, according to the invention, are iron ions). These nitrogen donor atoms can be aliphatic tertiary, secondary, or primary amines, or can belong to heterocyclic rings, such as pyridine.

[0070] According to a specific embodiment, a chelating agent capable of chelating at least one iron or manganese ion by at least three nitrogen atoms has formula (I) or (IB):

[0071]

[0072] in:

[0073] Each D is independently selected from the group consisting of: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-1-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, and thiazolyl-2-yl, each of which may optionally be substituted by one or more groups independently selected from the group consisting of: -F, -Cl, -Br, -OH, -OC1-C4 alkyl, -NH-CO-H, -NH-CO-C1-C4 alkyl, -NH2, -NH-C1-C4 alkyl, and -C1-C4 alkyl;

[0074] Each of R1 and R2 is independently selected from the following groups: C1-C 24 Alkyl, C 6-10 Aryl C1-C6 alkyl, C 6-10 Aryl, C 5-10 Heteroaryl C1-C6 alkyl groups, each of which may optionally be substituted with one or more groups selected from the group consisting of: -F, -Cl, -Br, -OH, -OC1-C4 alkyl, -NH-CO-H, -NH-CO-C1-C4 alkyl, -NH2, -NH-C1-C4 alkyl, and –SC1-C4 alkyl; and CH2CH2N(R10)(R11),

[0075] Where N(R10)(R11) is selected from the group consisting of the following items: two (C 1-44 alkyl)amino; di(C) 6-10 Aryl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; di(C) 6-10 Aryl C 1-6 Alkyl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; NR7, wherein R7 and the nitrogen atom N to which it is attached represent optional substitution by one or more C atoms. 1-20 Alkyl-substituted heterocyclic alkyl group, wherein the heterocyclic alkyl group is attached to the remainder of R1 via a nitrogen atom N; di(heterocyclic C 1-6Alkyl)amino, wherein each of the heterocyclic alkyl groups is independently optionally constituting one or more C 1-20 Alkyl substitution; and di(heteroaryl C) 1-6 Alkyl)amino, wherein each of the heteroaryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution;

[0076] R3 and R4 are independently selected from hydrogen, C1-C8 alkyl, C1-C8 alkyl-O-C1-C8 alkyl, C6-C 10 Aryloxy C1-C8 alkyl, C6-C 10 Aryl, C1-C8 hydroxyalkyl, C6-C 10 Aryl C1-C6 alkyl and C5-C 10 Heteroaryl C1-C6 alkyl groups and -(CH2) 0-4 C(O)OR5, wherein R5 is independently selected from: hydrogen, C1-C8 alkyl, and C 6-10 Aryl;

[0077] Q2 represents selecting the bridge from the group consisting of the following items: C 1-6 alkylene moiety, C 6-10 The aryl group may contain one or two C atoms. 1-3 alkylene unit and a C 6-10 The portion of the aryl unit, the bridge is optionally and independently selected by C 1-24 Alkyl and OH groups are substituted once or multiple times; and

[0078] X is selected from C=O and -[C(R6)2] 0-3 - where each R6 is independently selected from hydrogen, hydroxyl, C1-C4 alkoxy and C1-C4 alkyl.

[0079] In some implementations, particularly when the complex is a manganese complex, each or every R1 and R2 is independently selected from the group consisting of: C1-C 24 Alkyl, C 6-10 Aryl C1-C6 alkyl, C 6-10 Aryl, C5-C 10 Heteroaryl C1-C6 alkyl groups, each of which may optionally be substituted by one or more groups selected from the group consisting of: -F, -Cl, -Br, -OH, -OC1-C4 alkyl, -NH-CO-H, -NH-CO-C1-C4 alkyl, -NH2, -NH-C1-C4 alkyl and –SC1-C4 alkyl.

[0080] Such ligands (i.e., ligands of formulas (I) and (IB)) are referred to in the art as bispidons. The following characteristics, individually or in combination, are typical (but not essential) features of bispidons, provided the context allows (i.e., where there is no conflict):

[0081] • Each D group is either unsubstituted or substituted with one or more (usually one) C1-C4 alkyl groups;

[0082] • Every D group is identical;

[0083] • Each D group is optionally substituted with a pyridin-2-yl group;

[0084] • Each D group is an unsubstituted pyridin-2-yl group;

[0085] • Q2 is selected from -CH2CH2-, -CH2CH2CH2- and -CH2CHOHCH2-, each of which is optionally C1-C6 alkyl-substituted, wherein the bridge is typically unsubstituted;

[0086] • Each R1 and R2 group is independently selected from C1-C 24 Alkyl, C6-C 10 Aryl, C 6-10 Aryl C1-C6 alkyl, C5-C 10 Heteroaryl CH2 and CH2CH2N(R10)(R11), wherein –N(R10)(R11) are selected from –NMe2, –NEt2, –N(i-Pr)2, ;

[0087] • Each R1 or R2 group is independently C1-C 24 Alkyl, C6-C 10 Aryl or C 6-10 In the case of aryl C1-C6 alkyl groups, they are more typically selected independently from C1-C6. 18 Alkyl and C6-C 10 Aryl C1-C6 alkyl, and even more typically independently selected from: C1-C8 alkyl and C6-C 10 Aryl CH2;

[0088] Especially when the complex is a manganese complex, each R1 and R2 group is independently selected from C1-C2. 24 Alkyl and C6-C 10 Aryl C1-C 12 Alkyl groups, more typically independently selected from C1-C2. 18 Alkyl and C6-C 10 Aryl C1-C6 alkyl, and even more typically independently selected from: C1-C8 alkyl and C6-C10 Aryl CH2;

[0089] • In any R1 or R2, independently it is C5-C 10 In the case of a heteroaryl CH2 group, it is preferably selected from pyridin-2-ylmethyl, pyrazin-2-ylmethyl, quinoline-2-ylmethyl, pyrazol-1-ylmethyl, pyrazol-3-ylmethyl, pyrrole-2-ylmethyl, imidazole-2-ylmethyl, imidazole-4-ylmethyl, benzimidazole-2-ylmethyl, pyrimidin-2-ylmethyl, 1,2,3-triazol-1-ylmethyl, 1,2,3-triazol-2-ylmethyl, 1,2,3-triazol-4-ylmethyl, 1,2,4-triazol-3-ylmethyl, 1,2,4-triazol-1-ylmethyl, and thiazol-2-ylmethyl, among which pyridin-2-ylmethyl, quinoline-2-ylmethyl, imidazole-2-ylmethyl, and thiazol-2-ylmethyl are more typical;

[0090] • Typically, one of the R1 and R2 groups is C1-C. 24 Alkyl or C 6-10 Aryl C1-C6 alkyl, while the other of the R1 and R2 groups is C5-C6. 10 The heteroaryl CH2 group or CH2CH2N(R10)(R11), wherein –N(R10)(R11) is selected from –NMe2, –NEt2, –N(i-Pr)2, ;

[0091] One of the R1 and R2 groups is most typically C1-C. 18 Alkyl, wherein C1-C 12 Alkyl groups are preferred, C1-C8 alkyl groups are even more preferred, and CH3 is the most preferred; while the other R1 or R2 group is typically an optionally substituted pyridin-2-ylmethyl group, wherein unsubstituted pyridin-2-ylmethyl group is the most typical, or selected from CH2CH2N(R10)(R11), wherein –N(R10)(R11) is selected from –NMe2, –NEt2, –N(i-Pr)2, ;

[0092] • R1 and R2 are the same (for formula (I)), or each R1 is the same (for formula (II)), usually methyl or pyridin-2-ylmethyl;

[0093] • Groups R3 and R4 are the same.

[0094] Depending on the specific implementation scheme, bispidon is one of the following ligands:

[0095] 2,4-Di-(2-pyridyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylic acid dimethyl ester (N2py3o-C1), 2,4-di-(2-pyridyl)-3-(pyridin-2-ylmethyl)-7-methyl-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylic acid dimethyl ester (N2py3u-C1) and their iron complexes (FeN2py3o-C1, FeN2py3u-C1), which are described in WO 02 / 48301. Another particularly preferred bispidon is 9,9-dihydroxy-3-methyl-2,4-di-(2-pyridyl)-7-(1-(N,N-dimethylamine)-ethyl-2-yl)-3,7-diaza-bicyclo[3.3.1]nonane-1,5-dicarboxylic acid dimethyl ester and its iron complex, as described in WO 03 / 104234. Other preferred bispidons are those containing other N-alkyl groups, such as isobutyl, (n-hexyl) C6, (n-octyl) C8, (n-dodecyl) C12, (n-tetradecyl) C14, (n-octadecyl) C18 (instead of R). 1=methyl). Similarly, similar 3-pyridin-2-ylmethyl)-7-alkyl isomer ligands and their iron complexes are preferred. Examples of such bispidons are described in WO02 / 48301, WO 03 / 104379 and WO 2005 / 049778. Other preferred tetradentate bispidons are, in particular, 2,4-di-(2-pyridyl)-3,7-dimethyl-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate (N2py2), 2,4-di-(2-pyridyl)-3,7-dibutyl-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate; 2,4-di-(2-pyridyl)-3,7-dioctyl-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate; and 2,4-di-(2-pyridyl)-3,7-dibenzyl-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate. Manganese and iron complexes with tetradentate bispidons are known in the literature. P. Comba et al. (J. Chem. Soc., Dalton Trans., 3997-4002 (1998)) have described N2py2 and various manganese complexes prepared using this ligand. Various [Fe(N2py2)X2] complexes are known to those skilled in the art, where X =, for example, thiocyanate and acetate (see, for example, P. Comba et al., Inorg. Chim. Acta., 337, 407-419 (2002)). According to other embodiments, chelating agents capable of chelating at least one iron ion or manganese ion by means of a nitrogen atom have formulas (II) and (II-B):

[0096]

[0097] in:

[0098] Each Q is independently selected from -CR4R5CR6R7- and -CR4R5CR6R7CR8R9-;

[0099] R4, R5, R6, R7, R8 and R9 are independently selected from: H, C1-C4 alkyl and hydroxy C1-C4 alkyl;

[0100] Each of R1, R2, and R3 is independently selected from the group consisting of: hydrogen, C1-C 24 Alkyl group, CH2CH2OH, CH2COOH, CH2PO3H2, C5-C 10 Heteroaryl C1-C6 alkyl groups and CH2CH2N(R10)(R11),

[0101] Where N(R10)(R11) is selected from the group consisting of the following items: two (C 1-44 alkyl)amino; di(C) 6-10 Aryl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; di(C) 6-10 Aryl C 1-6 Alkyl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; NR7, wherein R7 and the nitrogen atom N to which it is attached represent optional substitution by one or more C atoms. 1-20 Alkyl-substituted heterocyclic alkyl group, wherein the heterocyclic alkyl group is attached to the remainder of R1 via a nitrogen atom N; di(heterocyclic C 1-6 Alkyl)amino, wherein each of the heterocyclic alkyl groups is independently optionally constituting one or more C 1-20 Alkyl substitution; and di(heteroaryl C) 1-6 Alkyl)amino, wherein each of the heteroaryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; and

[0102] Q2 is the bridge selected from the group consisting of the following items: C 1-6 alkylene moiety, C 6-10 The aryl group may contain one or two C atoms. 1-3 alkylene unit and a C 6-10 In the part of the aryl unit, the bridge can be optionally and independently selected by C. 1-24 Alkyl and OH groups may be substituted once or multiple times.

[0103] In some implementations, particularly when the complex is a manganese complex:

[0104] Each R1 is independently selected from the group consisting of the following: pyridin-2-ylmethyl, quinoline-2-ylmethyl, imidazole-2-ylmethyl, benzimidazole-2-ylmethyl, pyrazin-2-ylmethyl, pyrazol-1-ylmethyl, pyrazol-3-ylmethyl, 1,2,3-triazol-1-ylmethyl, 1,2,3-triazol-2-ylmethyl, 1,2,3-triazol-4-ylmethyl, 1,2,4-triazol-1-ylmethyl, 1,2,4-triazol-3-ylmethyl, thiazol-2-ylmethyl, and CH2CH2N(R10)(R11);

[0105] Each R2 is independently selected from: hydrogen, C1-C 24 Alkyl groups, CH2CH2OH, CH2COOH, and CH2PO3H2; and

[0106] R3 is selected from the following groups: H, C 1-24Alkyl groups, CH2CH2OH, CH2COOH, and CH2PO3H2.

[0107] The following features, individually or in combination, are typical (but not essential) features of the ligands of formulas (II) and (II-B), where the context allows (i.e., where there is no conflict):

[0108] • In the case where the ligand has the formula (II-B), the ligand is symmetrical, that is, each R1 is the same and each R2 is the same; and each Q group is the same at the same position in each ring (e.g., between the nitrogen atom with the bridging portion and the nitrogen atom substituted by R2).

[0109] • Each Q is identical, for example, each Q is -CR4R5CR6R7-, where R4, R5, R6, and R7 are usually H. This restriction limits the type of ligand commonly referred to as 1,4,7-triazacyclononane ligands.

[0110] • If any of R1, R2 and / or R3 is C5-C 10 For heteroaryl C1-C6 alkyl groups, such groups are selected from pyridin-2-ylmethyl, quinoline-2-ylmethyl, imidazole-2-ylmethyl, benzimidazole-2-ylmethyl, pyrazin-2-ylmethyl, 1,2,4-triazol-3-ylmethyl, 1,2,4-triazol-1-ylmethyl, thiazol-2-ylmethyl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, pyrazol-3-ylmethyl, and pyrazol-1-ylmethyl;

[0111] R1, R2, and / or R3 are typically C1-C independently. 24 Alkyl, pyridin-2-ylmethyl or quinoline-2-ylmethyl.

[0112] • If R1, R2 and / or R3 are heteroarylmethyl groups, then this will typically be pyridin-2-ylmethyl.

[0113] Especially when the complex is a manganese complex, R1 is usually pyridin-2-ylmethyl or quinoline-2-ylmethyl, usually pyridin-2-ylmethyl;

[0114] • -R1, -R2 and / or -R3 (such as, and especially when the complex is a manganese complex, R1) are -CH2CH2N(R10)(R11), wherein the reference is optionally made by one or more C 1-20 Any R10 and / or R11 moiety substituted with an alkyl group is typically unsubstituted, or substituted with only one C. 1-20 Alkyl substitution;

[0115] • Non-limiting examples of groups where R1, R2, and / or R3 (such as, and especially when the complex is a manganese complex, R1) is CH2CH2N (R10R11) include: di(p-methylbenzyl)amino, as di(C 6-10 Aryl C 1-4 An example of an alkyl)amino group; pyrroloalkyl, piperidinyl, or morpholinyl, as an example of NR7; di(piperidinylethyl)amino, as an example of di(heterocyclic alkyl C 1-6 An example of an alkyl)amino group; and a di(pyridin-2-ylethyl)amino group, as a di(heteroaryl C)amino group. 1-6 An example of an alkyl)amino group.

[0116] • If they exist, each –N(R10)(R11) is independently chosen from –NMe2, –NEt2, –N(i-Pr)2, The group formed;

[0117] • If R1, R2, and / or R3 (such as, and especially R2, when the complex is a manganese complex) are C1-C 24 Alkyl, then this is a C1-C6 alkyl, and is usually methyl;

[0118] Especially when the complex is a manganese complex, R3 is C1-C 24 Alkyl, more typically C1-C6 alkyl, and usually methyl, and typically the same as R2;

[0119] For ligands of formula (II-B), bridge Q2 is typically C. 1-6 Alkylene, typically ethylene or n-propylene, with ethylene being the most common.

[0120] According to a particular embodiment of the invention, the ligand of formula (II) or (II-B) is selected from the group consisting of: 1,4,7-trimethyl-1,4,7-triazacyclononane (Me3-TACN), 1,2-bis(4,7-dimethyl-1,4,7-triazacyclononane-1-yl)-ethane (Me4-DTNE), 1-(pyridin-2-ylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane, 1,4-bis(pyridin-2-ylmethyl)-7-methyl-1,4,7-triazacyclononane, etc. Nonane, 1,4,7-tris(pyridin-2-ylmethyl)-1,4,7-triazacyclononane, 1,2-bis(4-methyl-7-pyridin-2-yl-1,4,7-triazacyclononane-1-yl)-ethane, 1,3-bis(4-methyl-7-pyridin-2-yl-1,4,7-triazacyclononane-1-yl)-propane, 1-ethyl-4,7-bis(quinoline-2-ylmethyl)-1,4,7-triazacyclononane and 1-methyl-4,7-bis(quinoline-2-ylmethyl)-1,4,7-triazacyclononane. According to a particular embodiment, the ligand of formula (II) is selected from 1-(pyridin-2-ylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane and 1,4-bis(pyridin-2-ylmethyl)-7-methyl-1,4,7-triazacyclononane.

[0121] According to a particular embodiment of the invention, especially when the complex is a manganese complex, the ligand of formula (II) is selected from the group consisting of: 1,4,7-trimethyl-1,4,7-triazacyclononane, 1-(pyridin-2-ylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane, 1,2-bis(4-methyl-7-pyridin-2-yl-1,4,7-triazacyclononane-1-yl)-ethane, and 1,3-bis(4-methyl-7-pyridin-2-yl-1,4,7-triazacyclononane-1-yl)-propane. According to even more particular embodiments, the ligand of formula (II) is 1,4,7-trimethyl-1,4,7-triazacyclononane or 1-(pyridin-2-ylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane.

[0122] According to another embodiment, a chelating agent capable of chelating at least one iron or manganese ion by at least three nitrogen atoms has formula (III) or (IV):

[0123]

[0124] in:

[0125] Each -Q- is independently selected from -N(R)C(R1)(R2)C(R3)(R4)- and -N(R)C(R1)(R2)C(R3)(R4)C(R5)(R6)-;

[0126] Each -Q1- is independently selected from -N(R')C(R1)(R2)C(R3)(R4)- and -N(R')C(R1)(R2)C(R3)(R4)C(R5)(R6)-;

[0127] Each R is independently selected from: hydrogen; formed by C1-C 20 Alkyl, C2-C 20 alkenyl, C2-C 20 alkynyl group, C6-C 10 Aryl and C7-C 20 The group consisting of arylalkyl groups, each of which may optionally be composed of C1-C6 alkyl groups and / or C5-C6 alkyl groups. 10 Heteroaryl substitution; and CH2CH2N(R10)(R11),

[0128] Where N(R10)(R11) is selected from the group consisting of the following items: two (C 1-44 alkyl)amino; di(C) 6-10 Aryl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; di(C) 6-10 Aryl C 1-6 Alkyl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; NR7, wherein R7 and the nitrogen atom N to which it is attached represent optional substitution by one or more C atoms. 1-20 Alkyl-substituted heterocyclic alkyl group, wherein the heterocyclic alkyl group is attached to the remainder of R1 via a nitrogen atom N; di(heterocyclic C 1-6 Alkyl)amino, wherein each of the heterocyclic alkyl groups is independently optionally constituting one or more C 1-20 Alkyl substitution; and di(heteroaryl C) 1-6 Alkyl)amino, wherein each of the heteroaryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution;

[0129] The two –R' groups in the two Q1 groups together form the bridging portion –Q2-;

[0130] Q2 is the bridge selected from the group consisting of the following items: C 2-6 alkylene moiety, C 6-10 The arylene moiety may contain one or two C1-C3 alkylene units and one C6-C4 alkylene unit. 10 In the part of the aryl unit, the bridge can be optionally and independently selected by C. 1-24 Alkyl substitution once or multiple times; and

[0131] R1-R6 are each independently selected from: H, C 1-4 Alkyl and hydroxy C1-4 alkyl.

[0132] In some implementations, particularly when the complex is a manganese complex, each R is independently hydrogen, or selected from the group consisting of: C1-C 20 Alkyl, C2-C 20 alkenyl, C2-C 20 alkynyl group, C6-C 10 Aryl and C7-C 20 Arylalkyl groups, each of which may optionally be substituted with C1-C6 alkyl groups.

[0133] The following characteristics, individually or in combination, are typical (but not essential) characteristics of the ligands of formulas (III) and (IV), provided the context allows (i.e., where there is no conflict):

[0134] ·Q2, which can be present in the chelating agent of formula (III), is an ethylidene or n-propylidene bridge;

[0135] • Each -Q- is independently selected from -N(R)(CH2)2- and -N(R)(CH2)3-;

[0136] • Each -Q1- is independently selected from -N(R')(CH2)2- and -N(R')(CH2)3-;

[0137] Each R is selected from: hydrogen, C1-C 20 Alkyl, C6-C 10 Aryl, C7-C 20 Arylalkyl, pyridin-2-ylmethyl, quinoline-2-ylmethyl, imidazole-2-ylmethyl, benzimidazole-2-ylmethyl, more typically selected from hydrogen, methyl, ethyl, benzyl or pyridin-2-ylmethyl, and even more typically selected from hydrogen, methyl or benzyl;

[0138] Especially when the complex is a manganese complex, each R is selected from: hydrogen, C1-C 20 Alkyl and C6-C 10 Aryl groups, more typically selected from hydrogen, C1-C 20 Alkyl, C6-C 10 Aryl or C7-C 20 Arylalkyl groups are still more typically selected from hydrogen, methyl, ethyl, or benzyl groups;

[0139] R1-R6 are typically hydrogen or C. 1-4 Alkyl groups, still more typically hydrogen or methyl groups, such as hydrogen;

[0140] Especially when the complex is a manganese complex, groups with the same descriptive symbols (e.g., R, R1, Q1, etc.) are typically identical;

[0141] • The ligand has formula (III-A), i.e., a cross-bridged tetraza-1,4,8,11-cyclotetradecane ligand:

[0142]

[0143] Where R is as defined above with respect to equations (III) and (IV), including the particular implementation described above.

[0144] Typically, each R in formula (III-A) is independently selected from the group consisting of methyl, ethyl, and benzyl. Typically, each R is identical, usually methyl. Other suitable trans-bridging ligands (so named because of the bridge connecting two non-adjacent nitrogen atoms of the tetraazacycloalkane) are described in WO 98 / 39098 A1 (The University of Kansas). In some embodiments, the ligand of formula (III) or formula (III-A) is 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane.

[0145] Typical ligands of formula (IV) are tetraaza-1,4,7,10-cyclododecane and tetraaza-1,4,8,11-cyclotetradecane, in which each of the four hydrogen atoms bonded to the nitrogen atoms can be independently substituted with C1-C2. 20 Alkyl, C6-C 10 Aryl or C7-C 20 Arylalkyl. According to a particular embodiment, the ligand of formula (IV) can be a ligand of formula (IV) based on tetraaza-1,4,7,10-cyclododecane and a ligand based on tetraaza-1,4,8,11-cyclotetradecane, wherein each R group is hydrogen, C 1-20Alkyl or heteroarylmethyl. In these ligands, R is typically hydrogen, methyl, or pyridin-2-ylmethyl. According to particular embodiments, the ligands of formula (IV) include 1,4,7,10-tetraazacyclododecane, 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane, 1,4,7,10-tetra(pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane, 1-methyl-4,7,10-tris(pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane, 1,4-dimethyl-7,10-bis(pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane, and 1,4,7-trimethyl-11-(pyridin-2-ylmethyl)-1,4,7,10 -Tetraazacyclododecane, 1,4,8,11-tetraazacyclododecane, 1,4,8,11-tetra(pyridin-2-ylmethyl)-1,4,8,11-tetraazacyclododecane, 1-methyl-4,8,11-tris(pyridin-2-ylmethyl)-1,4,8,11-tetraazacyclododecane, 1,4-dimethyl-8,11-bis(pyridin-2-ylmethyl)-1,4,8,11-tetraazacyclododecane, and 1,4,8-trimethyl-11-(pyridin-2-ylmethyl)-1,4,8,11-tetraazacyclododecane and 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclododecane.

[0146] In some embodiments, particularly when the complex is a manganese complex, the ligand of formula (IV) can be a tetraaza-1,4,7,10-cyclododecane-based or tetraaza-1,4,8,11-cyclotetradecane-based ligand of formula (IV), wherein each R group is hydrogen or C 1-20 Alkyl groups. In these ligands, R is typically hydrogen or methyl. According to more particular embodiments, the ligands of formula (IV) include 1,4,7,10-tetraazacyclododecane, 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane, 1,4,8,11-tetraazacyclododecane, and 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclododecane.

[0147] According to another embodiment, a chelating agent capable of chelating at least one iron or manganese ion by at least three nitrogen atoms has the formula (V), (VB), or (VC):

[0148]

[0149] in:

[0150] Each -R1 is independently selected from -CH2N(C1-C 24The heteroaryl group is selected from: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, 1,2,4-triazol-1-yl, 1,2,4-triazol-3-yl, and thiazolyl-2-yl;

[0151] Each -R2 independently represents -R4-R5;

[0152] Each -R3 and each -R6 independently represents hydrogen, or a group selected from the following: C1-C6 alkyl, C6 ... 10 Aryl, C5-C 10 heteroaryl, C6-C 10 Aryl C1-C6 alkyl and C5-C 10 Heteroaryl C1-C6 alkyl groups, each of which may optionally be C1-C6 alkyl substituted;

[0153] Each -R4- independently represents a C1-C6 alkylene group that is optionally alkyl-substituted;

[0154] Each -R5 independently represents -CH2N(C1-C 24 The heteroaryl group is selected from the group consisting of: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-1-yl, and thiazolyl-2-yl;

[0155] Each -NR7 independently represents where R7 and the nitrogen atom N it is attached to are optionally represented by one or more C atoms. 1-20 The alkyl-substituted heterocyclic alkyl group, which is attached to R4 via a nitrogen atom N; and

[0156] Q2 represents selecting the bridge from the group consisting of the following items: C 1-6 alkylene moiety, C 6-10 The aryl group may contain one or two C atoms. 1-3 alkylene unit and a C 6-10 In the part of the aryl unit, the bridge is optionally and independently selected by C.1-24 Alkyl and OH groups may be substituted once or multiple times.

[0157] In some implementations, particularly when the complex is a manganese complex, –R3 or –R6 cannot be one of the possible options allowed for –R1.

[0158] It should be understood that the ligands of formulas (VB) and (VC) are effectively dimers of the ligand of formula (V), wherein the bridge Q2 occupies the position of the R6 or R3 group, respectively. Among the ligands of formulas (V), (VB), and (VC), the ligand of formula (V) is the most typical. Among the bridged ligands, the ligand of formula (VB) is more typical than that of formula (VC). Furthermore, the following features, individually or in combination, are typical (but not essential) features of the ligands of formulas (V), (VB), and (VC), provided the context allows (i.e., without conflict):

[0159] Groups with the same descriptive symbols, such as R1, R2 (and R4 and R5 within the definition of R2), R3, R6, and Q2, are identical;

[0160] • R1 is an optionally substituted pyridin-2-yl group, especially an unsubstituted pyridin-2-yl group;

[0161] • In it, -R1 is selected from -CH2N(C 1-24 In embodiments of alkyl)2 and -CH2NR7, the nitrogen-containing group attached to the methylene group as described with respect to these possible options is selected from the group consisting of: -NMe2, -NEt2, -N(i-Pr)2, ;

[0162] -R4- is -CH2-.

[0163] • In the case of alkyl-substituted heteroaryl groups, R5 is optionally substituted pyridin-2-yl, of which unsubstituted pyridin-2-yl is most typical;

[0164] • Depending on other specific implementations, R5 can be -CH2N(C1-C) 24 The nitrogen-containing group attached to the methylene group, or -CH2NR7, is selected from the group consisting of: NMe2, NEt2, N(i-Pr)2, ... ;

[0165] • Each R3 and each R6 independently represents hydrogen, or a group selected from the following: C1-C6 alkyl, C6 ... 10 Aryl, C6-C 10 Aryl C1-C6 alkyl, C5-C 10heteroaryl, C6-C 10 Aryl C1-C6 alkyl and C5-C 10 Heteroaryl C1-C6 alkyl groups, each of which may optionally be C1-C6 alkyl substituted;

[0166] Especially when the complex is a manganese complex, each R3 and each R6 independently represents hydrogen, or a group selected from the following: C1-C6 alkyl, C6 ... 10 Aryl and C6-C 10 Aryl C1-C6 alkyl, each of which may optionally be C1-C6 alkyl substituted;

[0167] • Each R3 is selected from hydrogen, methyl, and benzyl;

[0168] • Q2 is selected from -CH2CH2-, -CH2CH2CH2- and -CH2CHOHCH2-, each of which is optionally C1-C6 alkyl-substituted, wherein the bridge is typically unsubstituted;

[0169] • Each R6 is typically selected from hydrogen, methyl, benzyl, and pyridin-2-ylmethyl, with R6 most typically selected from methyl and pyridin-2-ylmethyl;

[0170] Especially when the complex is a manganese complex, each R6 is typically selected from hydrogen, methyl and benzyl, with R6 being most typically methyl.

[0171] According to a particular embodiment, the ligand of formula (V) is N-methyl-N-(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine (MeN3Py) or N-benzyl-N-(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine (BzN3Py), both disclosed by Klopstra et al. (Eur. J. Inorg. Chem., 4, 846-856 (2006). Other preferred ligands of formula (V) are N,N-bis(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine (N4Py), disclosed in WO 95 / 34628; and N,N-bis(pyridin-2-yl-methyl)-1,1-bis(pyridin-2-yl)-1-aminoethane (MeN4py), as disclosed in EP 0. N,N-bis(pyridin-2-yl-methyl-1,1-bis(pyridin-2-yl)-2-phenyl-1-aminoethane, as disclosed in EP 0 909 As disclosed in 809. Further examples of ligands of formula (V) include: N-methyl-N-(pyridin-2-ylmethyl)-1,1-bis(pyridin-2-yl)-1-aminoethane, N-benzyl-N-(pyridin-2-ylmethyl)-1,1-bis(pyridin-2-yl)-1-aminoethane, N-methyl-N-(pyridin-2-ylmethyl)-1,1-bis(pyridin-2-yl)-2-phenyl-1-aminoethane, and N-benzyl-N-(pyridin-2-ylmethyl)-1,1-bis(pyridin-2-yl)-2-phenyl-1-aminoethane. Another example of a ligand of formula (V) is N-methyl-N-(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine.

[0172] In some embodiments, the ligand of formula (VB) is selected from N-methyl-N,N',N'-tris(pyridin-2-ylmethyl)ethylenediamine, N-butyl-N,N',N'-tris(pyridin-2-ylmethyl)-1,2-ethylenediamine, N-octyl-N,N',N'-tris(pyridin-2-ylmethyl)-1,2-ethylenediamine, N,N,N',N'-tetra(pyridin-2-ylmethyl)ethylenediamine, N,N,N',N'-tetra(benzimidazol-2-ylmethyl)ethylenediamine, and 2,6-bis(pyridin-2-ylmethyl)-1,1,7,7-tetra(pyridin-2-yl)-2,6-diazeptane.

[0173] According to another embodiment, a chelating agent capable of chelating at least one iron or manganese ion by at least three nitrogen atoms has formula (VI):

[0174] N(CY2-R1)3(VI)

[0175] in:

[0176] Each -R1 is independently selected from: -CY2N(C1-C 24 Alkyl)2;-CY2NR7, wherein R7 and the nitrogen atom N to which it is attached represent optionally being bonded by one or more C atoms. 1-6 Alkyl-substituted heterocyclic alkyl groups, wherein the heterocyclic alkyl group is connected to the remainder of R1 via a nitrogen atom N; or optionally, a C1-C6 alkyl-substituted heteroaryl group, wherein the heteroaryl group is selected from: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-1-yl, pyrazol-3-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, 1,2,4-triazol-1-yl, 1,2,4-triazol-3-yl, and thiazolyl-2-yl; and

[0177] Each Y is independently selected from H, CH3, C2H5, and C3H7.

[0178] The following characteristics, individually or in combination, are typical (but not necessary) features of the ligands of formula (VI) where the context allows (i.e., where there is no conflict):

[0179] • Each Y is H;

[0180] -R1 is selected from -CH2N(C1-C 24 Alkyl)2 and -CH2NR7, wherein a particular embodiment is described with respect to these possible options, wherein the nitrogen-containing group attached to the methylene group is selected from -NMe2, -NEt2, -N(i-Pr)2, Those in the group;

[0181] • Each R1 is typically an optionally substituted pyridin-2-yl group;

[0182] Each R1 is more typically unsubstituted pyridin-2-yl.

[0183] According to one specific embodiment, the ligand of formula (VI) is N,N,N-tris(pyridin-2-yl-methyl)amine (TPA), which has been described, for example, in U.S. Patent Nos. 5,850,086 (Que, Jr. et al.) and 6,153,576 (Blum et al.).

[0184] According to another embodiment, a chelating agent capable of chelating at least one iron or manganese ion by at least three nitrogen atoms has formula (VII) or (VII-B):

[0185] R1R2N-X-NR1R2 (VII); and R1R2N-X-NR2(-Q2-R2N) n-X-NR1R2 (VII-B);

[0186] in:

[0187] -X- is selected from -CY2CY2-, cis- or trans-1,2-cyclohexylene, -CY2CY2CY2-, -CY2C(OH)YCY2-, wherein each Y is independently selected from H, CH3, C2H5 and C3H7;

[0188] n is an integer from 0 to 10;

[0189] Each R1 group is independently an alkyl, heterocyclic alkyl, heteroaryl, aryl, arylalkyl, or heteroarylalkyl group, each of which may optionally be substituted with a substituent selected from the group consisting of: hydroxyl, alkoxy, phenoxy, phosphonate, carboxylate, formamide, carboxylic ester, sulfonate, amine, monoalkylamine, or dialkylamine and N. + (R3)3, wherein R3 is selected from hydrogen, alkyl, alkenyl, arylalkyl, arylalkenyl, hydroxyalkyl, aminoalkyl and alkyl ether;

[0190] Each R2 is –CZ2-R4, wherein each Z is independently selected from H, CH3, C2H5, C3H7; and each –R4 is independently selected from optionally substituted –N(C1-C) 24 Alkyl)2;-NR7, wherein each -NR7 independently represents R7 and the nitrogen atom to which it is attached. N represents optionally being bound by one or more C atoms. 1-6 The portion of an alkyl-substituted heterocyclic alkyl group, the heterocyclic alkyl group being linked to CZ2 via a nitrogen atom N; and optionally a C1-C6 alkyl-substituted heteroaryl group, the heteroaryl group being selected from the group consisting of: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrolo-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-1-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, and thiazolyl-2-yl; and CH2N(R10)(R11),

[0191] Where N(R10)(R11) is selected from the group consisting of the following items: two (C 1-44 alkyl)amino; di(C) 6-10 Aryl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; di(C) 6-10 Aryl C 1-6Alkyl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; NR7, wherein R7 and the nitrogen atom N to which it is attached represent optional substitution by one or more C atoms. 1-20 Alkyl-substituted heterocyclic alkyl group, wherein the heterocyclic alkyl group is attached to the remainder of R1 via a nitrogen atom N; di(heterocyclic C 1-6 Alkyl)amino, wherein each of the heterocyclic alkyl groups is independently optionally constituting one or more C 1-20 Alkyl substitution; and di(heteroaryl C) 1-6 Alkyl)amino, wherein each of the heteroaryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; and

[0192] Q2 is the bridge selected from the group consisting of the following items: C 1-6 Alkylene bridges, C 6-10 Aleurone bridges may contain one or two Cs 1-3 alkylene unit and a C 6-10 The bridge of the subarylene unit, which can be optionally and independently selected by C 1-24 Alkyl and OH groups may be substituted once or multiple times.

[0193] In some implementations, particularly when the complex is a manganese complex, n is 1. In some cases, R1 cannot be one of the possible options allowed for R2.

[0194] In some embodiments, particularly when the complex is a manganese complex, each -R2 group is independently –CZ2-R4, wherein each Z is independently selected from H, CH3, C2H5, C3H7; and each -R4 is independently selected from optionally substituted -N(C1-C) groups. 24 Alkyl)2;-NR7, wherein each -NR7 independently represents R7 and the nitrogen atom to which it is attached. N represents optionally being bound by one or more C atoms. 1-6 The portion of an alkyl-substituted heterocyclic alkyl group, the heterocyclic alkyl group being linked to CZ2 via a nitrogen atom N; and optionally a C1-C6 alkyl-substituted heteroaryl group, the heteroaryl group being selected from the group consisting of: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-1-yl, pyrazol-3-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, 1,2,4-triazol-1-yl, 1,2,4-triazol-3-yl, and thiazolyl-2-yl.

[0195] The following characteristics, individually or in combination, are typical (but not essential) characteristics of the ligands of formulas (VII) and (VII-B), where the context allows (i.e., where there is no conflict):

[0196] • Each Y is typically H;

[0197] • X is typically -CH2CH2- or 1,2-cyclohexylene;

[0198] • n is typically an integer from 0 to 4, more typically from 0 to 3, or even more typically from 0 to 2, and most typically n = 0 or 1, and in the case that the complex is a manganese complex, n is typically 1;

[0199] • Q2 is typically ethylene, n-propylidene bridged, or cis- or trans-1,2-cyclohexylene;

[0200] Especially when the complex is a manganese complex, Q2 is typically an ethylene or n-propylene bridge;

[0201] • Each Z is typically hydrogen;

[0202] • Typically, and especially when the complex is an iron complex, X = Q2;

[0203] • R4, for example, in –R4 is -NR7 or -N(C1-C 24 In the case of alkyl)2, choose from the group consisting of the following: -NMe2, -NEt2, -N(i-Pr)2, ;

[0204] • R4 can be optionally C1-C6 alkyl-substituted with pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrolo-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, or 1,2,4-triazol-3-yl In the case of the group consisting of 1,2,4-triazol-1-yl or thiazolyl-2-yl groups, this will typically be selected from pyridin-2-yl, imidazole-2-yl, imidazole-4-yl or benzimidazole-2-yl groups that are optionally C1-C6 alkyl-substituted, wherein unsubstituted pyridin-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl groups are more typical, and unsubstituted pyridin-2-yl is the most typical;

[0205] • Typically, and especially when the complex is a manganese complex, the two R4 groups (or four R4 groups in the ligand of formula (VII-B)) are selected from pyridin-2-yl, imidazol-2-yl, imidazol-4-yl, or benzimidazol-2-yl (each of which may optionally be C1-C6 alkyl-substituted), particularly where Z is hydrogen, more typically substituted pyridin-2-yl (where Z is hydrogen), and most typically unsubstituted pyridin-2-yl (where Z is hydrogen) (i.e., the two R2 groups (or four in the ligand of formula (VII-B)) are pyridin-2-ylmethyl); and / or the two R1 groups are independently optionally substituted C1-C6 alkyl groups. 24 Alkyl groups, more typically unsubstituted C1-C 24 Alkyl groups, such as C1-C 18 Alkyl groups, such as where each of the two R1 groups is a methyl group;

[0206] One or both R1 groups in formula (VII) or (VII-B) may be independently, optionally substituted C1-C groups. 24 Alkyl groups, more typically unsubstituted C1-C 24 Alkyl groups, such as C1-C 18 Alkyl groups, such as those in which one or both R1 groups are methyl;

[0207] One or both R1 groups in formula (VII) or (VII-B) can be independently, optionally substituted, C6-C. 10 Aryl C1-C 24 Alkyl groups, more typically unsubstituted C6-C 10 Aryl C1-C 24 Alkyl groups, such as C6-C 10 Aryl C1-C 12 Alkyl groups, most typically benzyl groups;

[0208] One or both R1 groups in formula (VII) or (VII-B) can independently be CZ2R4, where Z is as defined with respect to part R2 and is typically hydrogen, and R4 can be optionally C1-C6 alkyl-substituted pyridin-2-yl, pyrazin-2-yl, quinolin-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,3-trimethylpyridinium chloride, pyrimid ... The 1-yl azole, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-1-yl and thiazolyl, typically selected from pyridin-2-yl, imidazole-2-yl, imidazole-4-yl and benzimidazole-2-yl alkyl-substituted pyridin-2-yl, more typically selected from pyridin-2-ylmethyl, imidazole-2-ylmethyl, imidazole-4-ylmethyl or benzimidazole-2-ylmethyl;

[0209] • Typically, all R1 groups in formula (VII) or (VII-B) are identical and are typically selected from pyridin-2-ylmethyl, imidazole-2-ylmethyl, imidazole-4-ylmethyl or benzimidazole-2-ylmethyl;

[0210] More typically, for formula (VII), one R1 group is identical to the two R2 groups, and is typically all selected from pyridin-2-ylmethyl, imidazole-2-ylmethyl, imidazole-4-ylmethyl, or benzimidazole-2-ylmethyl; similarly, both R1 groups are typically selected from pyridin-2-ylmethyl, imidazole-2-ylmethyl, imidazole-4-ylmethyl, or benzimidazole-2-ylmethyl.

[0211] Especially when the complex is a manganese complex, each R1 group is independently alkyl, aryl, or arylalkyl, each of which may optionally be substituted with a substituent selected from the group consisting of: hydroxyl, alkoxy, phenoxy, phosphonate, carboxylic ester, formamide, carboxylic ester, sulfonate, amine, monoalkylamine, or dialkylamine and N. + (R3)3, wherein R3 is selected from hydrogen, alkyl, alkenyl, arylalkyl, arylalkenyl, hydroxyalkyl, aminoalkyl and alkyl ether.

[0212] Specific embodiments of the ligands of formula (VII) are N,N'-dimethyl-N,N'-bis(pyridin-2-ylmethyl)ethylene-1-2-diamine and N,N'-dimethyl-N,N'-bis(pyridin-2-ylmethyl)-cyclohexane-1-2-diamine, as disclosed by J Glerup et al. (Inorg. Chem., 33, 4105-4111 (1994)). Specific embodiments of the ligands of formula (VII) with one R1 and both R2 being –CH2-R4 (trispicen ligands) are described in WO 02 / 077145 and EP 1 001 009A. The most suitable example of a trispicen ligand is N-C1-C 20-alkyl-N,N',N'-tris(pyridin-2-ylmethyl)-1,2-ethylenediamine, wherein N-methyl-N,N',N'-tris(pyridin-2-ylmethyl)-1,2-ethylenediamine, N-butyl-N,N',N'-tris(pyridin-2-ylmethyl)-1,2-ethylenediamine and N-octyl-N,N',N'-tris(pyridin-2-ylmethyl)-1,2-ethylenediamine are most preferred. The ligand Tpen (N,N,N',N'-tetra(pyridin-2-ylmethyl)ethylenediamine) is described in WO 97 / 48787. S. Tong et al. (Open Journal of Inorganic Chemistry, 2, 75-80 (2012)) have described the synthesis of the ligand N,N,N',N'-tetra(benzimidazol-2-ylmethyl)ethylene-1,2-diamine. Other suitable trispicens are described in WO 02 / 077145 and EP 1 001 009 A. Further examples of trispicens are described in WO 00 / 12667, WO2008 / 003652, WO 2005 / 049778, EP 2 228 429, and EP 1 008 645.

[0213] According to another embodiment, a chelating agent capable of chelating at least one iron or manganese ion by at least three nitrogen atoms has formula (VIII) or (VIII-B):

[0214]

[0215] in:

[0216] Each Q group independently represents –CY2– or –CY2CY2–, where each Y is independently selected from hydrogen, C 1-24 Alkyl or C 6-10 Aryl;

[0217] Each D group independently represents a heteroaryl group or a group of the formula –NR–, provided that at least one D group represents a heteroaryl group;

[0218] Each D1 group is represented by the group with the formula –NR'–.

[0219] The two –R' groups of the two D1 groups together form the bridging region -Q2-;

[0220] Q2 is the bridge selected from the group consisting of the following items: C 1-6 alkylene moiety, C 6-10 The arylene moiety may contain one or two C1-C3 alkylene units and one C6-C4 alkylene unit. 10In the part of the aryl unit, the bridge can be optionally and independently selected by C. 1-24 Alkyl and OH groups are substituted once or multiple times; and

[0221] Each R group independently represents H and C. 1-24 Alkyl, C 6-10 Aryl or C 5-10 Mixed aromatic compounds.

[0222] The following features, individually or in combination, are typical (but not essential) features of the ligands of formulas (VIII) and (VIII-B), where the context allows (i.e., where there is no conflict):

[0223] Each R is typically selected independently from hydrogen or methyl;

[0224] • In the presence of bridge Q2, this is typically an ethylene or n-propylidene bridge;

[0225] • Each R group is typically identical;

[0226] • Each Q is typically –CY2–;

[0227] Y is typically hydrogen, and therefore each Q is typically –CH2–; and

[0228] • When group D is a heteroaryl group, this is typically a pyridyl group, especially a pyridin-2,6-diyl group.

[0229] According to a particular embodiment, the ligand of formula (VIII) has formula (VIII-A), where R is as defined with respect to formulas (VIII) and (VIII-B), including the particular embodiment just described above:

[0230]

[0231] According to specific embodiments, the ligands of formula (VIII) (and formula (VIII-A)) are selected from 2,11-diaza[3.3](2,6-pyridinophane) (pyridinophane) (compounds of formula (VIII-A) where each R is hydrogen) and N,N'-dimethyl-2,11-diaza[3.3](2,6-pyridinophane) (compounds of formula (VIII-A) where each R is methyl), as described in WO 99 / 065905 A1 (Unilever plc, etc.). According to another embodiment, a chelating agent capable of chelating at least one iron or manganese ion by at least three nitrogen atoms has formula (IX):

[0232] R1-CY2-(NR3)-CY2-R2-CY2-(NR3)-CY2-R1(IX)

[0233] in:

[0234] Each Y is independently selected from H, CH3, C2H5, and C3H7;

[0235] Each R1 is independently selected from C5-C6 alkyl-substituted C5-C6 alkyl groups. 10 heteroaryl, of which C5-C 10 The heteroaryl group is selected from pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-1-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, and thiazolyl-2-yl;

[0236] R2 is selected from C5-C6 heteroaryl groups with optional C1-C6 alkyl substitution, wherein the C5-C6 heteroaryl group is selected from pyridine-2,6-diyl, pyrazin-2,6-diyl, pyrazole-3,5-diyl, pyrazole-1,3-diyl, pyrrole-2,5-diyl, imidazole-2,5-diyl, imidazole-1,4-diyl, pyrimidine-2,6-diyl, 1,2,4-triazole-3,5-diyl, 1,2,4-triazole-1,3-diyl, 1,2,4-triazole-2,4-diyl, 1,2,3-triazole-1,4-diyl, 1,2,3-triazole-2,5-diyl, and thiazole-2,5-diyl.

[0237] Each R3 is independently selected from C1-C6 substituted C. 1-24 Alkyl, C 6-10 Aryl, C 6-10 Aryl C1-C 24 Alkyl, C 5-10 heteroaryl, C 5-10 heteroaryl C1-C 24 alkyl.

[0238] The following characteristics, individually or in combination, are typical (but not necessary) characteristics of the ligands of formula (IX), provided the context allows (i.e., where there is no conflict):

[0239] • Each Y is typically hydrogen;

[0240] • Each R1 is independently selected from unsubstituted C5-C 10 heteroaryl, the C5-C 10The heteroaryl groups are typically selected independently from pyridin-2-yl, quinolin-2-yl, imidazo-2-yl, and thiazo-2-yl;

[0241] • Each R1 is the same;

[0242] • Each R1 = pyridin-2-yl is the most typical;

[0243] • R2 is typically unsubstituted pyridine-2,6-dimethyl;

[0244] • Each R3 is independently selected from C1-C6 substituted C 1-18 Alkyl, C 6-10 Aryl C1-C 18 Alkyl, pyridin-2-ylmethyl, pyrazin-2-ylmethyl, quinoline-2-ylmethyl, pyrazol-1-ylmethyl, pyrazol-3-ylmethyl, pyrrole-2-ylmethyl, imidazole-2-ylmethyl, imidazole-4-ylmethyl, benzimidazole-2-ylmethyl, pyrimidin-2-ylmethyl, 1,2,3-triazol-1-ylmethyl, 1,2,3-triazol-2-ylmethyl, 1,2,3-triazol-4-ylmethyl, 1,2,4-triazol-3-ylmethyl, 1,2,4-triazol-1-ylmethyl, and thiazol-2-ylmethyl;

[0245] Typically, each R3 is independently selected from unsubstituted C. 1-12 Alkyl, C6 aryl C1-C 12 Alkyl, pyridin-2-ylmethyl, quinoline-2-ylmethyl, pyrazol-1-ylmethyl, pyrazol-3-ylmethyl, imidazole-2-ylmethyl, imidazole-4-ylmethyl, benzimidazole-2-ylmethyl, 1,2,3-triazol-1-ylmethyl, 1,2,3-triazol-2-ylmethyl, 1,2,3-triazol-4-ylmethyl, 1,2,4-triazol-3-ylmethyl, 1,2,4-triazol-1-ylmethyl, and thiazolyl-2-ylmethyl;

[0246] More typically, each R3 is independently selected from unsubstituted C 1-8 Alkyl, C6 aryl CH2, pyridin-2-ylmethyl, quinoline-2-ylmethyl, imidazole-2-ylmethyl, imidazole-4-ylmethyl, benzimidazole-2-ylmethyl;

[0247] Even more typically, each R3 is independently selected from methyl, CH2C6H5, and pyridin-2-ylmethyl;

[0248] • Each R3 is the same.

[0249] In one specific embodiment of the ligand of formula (XI), Y = H, R1 = pyridin-2-yl, R2 = pyridin-2,6-diyl, and R3 = methyl, namely 2,6-bis[(N-methyl-{N-(2-pyridylmethyl)}amino)methyl]pyridine.

[0250] Another class of ligands that can exist as polydentate ligands for manganese complexes are porphyrin or porphyrinazine ligands. These are described in detail in WO2012 / 027216 A1 (The Trustees of Princeton University).

[0251] In this document, the term porphyrin is used, as is customary in the art, to refer to a tetradentate tetracyclic macrocycle comprising four pyrrole rings linked by four methine bridges, each of which is connected to an adjacent pyrrole moiety at its 2- and 5-carbon atoms by a methine (=C(H)-) bimolecular group. The parent compound is named porphyrine; when substituted, the resulting compounds are called porphyrins.

[0252] Similarly, the term porphyrazine is used herein to refer to a class of macrocycles associated with porphyrins, but in which the four pyrrole rings are linked by -N= rather than a methine bridge, wherein the parent compound is called porphyrazine and its derivatives are called porphyrazines. For the avoidance of ambiguity, it should be understood that porphyrazine derivatives containing a cyclic moiety fused with the 3- and 4-carbon atoms of the pyrrole portion within a porphyrazine are porphyrazines.

[0253] In some implementations, particularly when the complex is an iron complex, the complex does not contain porphyrin or porphyrin ligands.

[0254] According to a particular embodiment, especially when the complex is an iron complex, the polydentate ligand is not a tetrapyrrole-containing compound. "Tetrapyrrole-containing compound" herein means a compound comprising four pyrrole rings or their reduced forms (such as the pyrrolin ring found in the dihydroporphyrin ring of chlorophyll; a dihydroporphyrin ring consisting of three pyrroles and one pyrrolin (3,4-dihydropyrrole) moiety connected by four methine (-C(H)=) bridges, each of which is connected to an adjacent pyrrole or pyrrolin moiety via a methine bimole at its 2- and 5-carbon atoms).

[0255] Besides porphyrins, porphyrinazines, and dihydroporphyrins, there are many other macrocyclic compounds based on four pyrrole or reduced pyrrole units linked by methylene or imine (-N=) bridges. For example, a corrin ring comprises four pyrrolin moieties linked by three methylene bridges, all but one of which are connected to adjacent pyrrolin moieties at their 2- and 5-carbon atoms via methylene bimolecular groups; however, two of the pyrrolin moieties are directly linked from the 2-carbon to the 5-carbon atom of one moiety. Phthalocyanine compounds are macrocycles comprising four pyrrole-based five-membered rings linked by four imine bridges, each of which has a benzene ring fused to the 3- and 4-positions of the five-membered ring, and each of these five-membered rings is connected to an adjacent five-membered ring at its 2- and 5-carbon atoms via an imine bimolecular group.

[0256] According to embodiments of the invention in which the polydentate ligand is not a tetrapyrrole-containing compound, excluding each of the macrocycles of the types just mentioned above, it should be understood that the use of the term tetrapyrrole-containing compound to cover compounds that do not necessarily contain four pyrrole rings is consistent with the common use in the art of describing compounds such as phthalocyanines and dihydroporphyrins as tetrapyrrole-containing compounds, even if these compounds do not strictly contain four pyrrole rings structurally.

[0257] In the case where the complex contains a porphyrin or porphyrinazine ligand, the complex also contains a manganese ion, i.e., the complex is a manganese complex. Typically, upon chelation with a manganese ion, two of the pyrrole moieties within the porphyrin or porphyrinazine ligand are deprotonated and thus become negatively charged. Subsequently, the total charge of the resulting manganese complex is reduced by 2. Therefore, the doubly deprotonated porphyrin or porphyrinazine ligand generally stabilizes manganese ions with more positive oxidation states. In some embodiments, when the ligand is a porphyrin or porphyrinazine ligand, one or more manganese ions have one or more oxidation states selected from the group consisting of II, III, and IV. In some embodiments, when the ligand is a porphyrin or porphyrinazine ligand, the manganese complex also contains up to two additional ligands independently selected from the following: halide, oxo, aquo, hydroxo, cyanide, hydrogenphosphate, C1-C8 alcohol, and C1-C8 alkoxide.

[0258] In some implementations, porphyrin has the formula (X):

[0259]

[0260] in:

[0261] Each R 1 R2 R 3 and R 4 It is a 5- to 10-membered N-heteroaryl group optionally selected from the group consisting of one or more of the following: C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group and C 1-24 Alkylphenyl, C 1-24 alkylnaphthalene, C 1-24 Alkoxy and phenoxy, each of which may optionally be selected from C 1-6 Alkyl, halogen (halogen) and C 1-6 One or more substitutions in the group consisting of haloalkyl groups;

[0262] Each R 1a R 2a R 3a and R 4a Choose independently the group consisting of the following items: C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group and C 1-24 Alkylphenyl, C 1-24 alkylnaphthalene, C 1-24 Alkoxy and phenoxy, each of which may optionally be selected from C 1-6 Alkyl, halogenated and C 1-6 One or more substitutions in the group consisting of haloalkyl groups; and

[0263] n is between 0 and 2.

[0264] To avoid ambiguity, in the case of two deprotonations in the pyrrole moiety within the porphyrin ligand of formula (X), the ligand has formula (Xa):

[0265] .

[0266] In some implementations, n in equation (X) or (Xa) is 0.

[0267] Typically, R in equation (X) or (Xa) is... 1 R 2 R 3 and R 4 Independently selected from equations (X-b1), (X-b2), (X-b3), and (X-b4):

[0268]

[0269] The wavy line will CR 1 CR 2 CR 3 and CR 4 The key is divided equally; and

[0270] R5, R6, R7, R8, R9 and R 10 Choose independently the group consisting of the following items: hydrogen, C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group, C 1-24 Alkyl C 6-10 Aryl, C 1-24 Alkyloxy and phenoxy, each of which is optionally C 1-6 Alkyl, halogenated, CH2CF3 and CF3 substituted.

[0271] Typically, R1, R2, R3, and R4 groups are identical. Usually, R5, R6, R7, R8, R9, and R... 10 The group is methyl.

[0272] Preferred ligands for compound (X) are tetra-(N-methyl)-2-pyridyl-porphyrin (TM2PyP), tetra-(N-methyl)-4-pyridyl-porphyrin (TM4PyP), tetra-(N,N-dimethyl)-imidazolium-porphyrin (TDMImP), tetra-(N,N-dimethyl)-benzimidazolium-porphyrin (TDMBImP) and 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphyrin tetra(methyl chloride).

[0273] In some implementations, the porphyrin ligand has the formula (XI):

[0274]

[0275] in:

[0276] A 1 A 2 A 3 A 4 B 1 B 2 B 3 B 4 C 1 C 2 C 3 C 4 D 1 D 2 D 3and D 4 Independently selected from N, CH, CR n N + -H and N + -R n The condition is that at most one of A1, B1, C1, and D1 is N, N + -H or N + -R n No more than one of A2, B2, C2, and D2 is N, N + -H or N + -R n No more than one of A3, B3, C3, and D3 is N, N + -H or N + -R n And at most one of A4, B4, C4, and D4 is N, N + -H or N + -R n And among them:

[0277] Each R n Selected independently from C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group and C 1-24 Alkylphenyl, C 1-24 alkylnaphthalene, C 1-24 Alkoxy and phenoxy, each of which may optionally be selected from C 1-6 Alkyl, halogenated and C 1-6 One or more substitutions in the group consisting of haloalkyl groups;

[0278] Each R 1a R 2a R 3a and R 4a Choose independently the group consisting of the following items: C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group and C 1-24 Alkylphenyl, C 1-24 alkylnaphthalene, C 1-24 Alkoxy and phenoxy, each of which may optionally be selected from C 1-6 Alkyl, halogenated and C 1-6 One or more substitutions in the group consisting of haloalkyl groups;

[0279] Each R 1R 2 R 3 and R 4 It is a 5- to 10-membered N-heteroaryl group optionally selected from the group consisting of one or more of the following: C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group and C 1-24 Alkylphenyl, C 1-24 alkylnaphthalene, C 1-24 Alkoxy and phenoxy, each of which may optionally be selected from C 1-6 Alkyl, halogenated and C 1-6 One or more substitutions in the group consisting of haloalkyl groups; and

[0280] n is between 0 and 2.

[0281] To avoid ambiguity, in the case of two deprotonations in the pyrrole moiety within the porphyrin ligand of formula (XI), the ligand has formula (XI-a):

[0282] .

[0283] In some implementations, n in equation (XI) or (XI-a) is 0.

[0284] In some implementations, each R in formula (XI) or (XI-a) n It is C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, C 6-10 Aryl, C 1-24 alkynyl group, C 1-24 Alkyl C 6-10 Aryl, C 1-24 Alkyloxy and phenoxy, each of which is optionally C 1-6 Alkyl, halogenated, CH2CF3 and CF3 substituted.

[0285] Typically, D1, D2, D3, and D4 are the same, and each is usually N. + -R n Typically, A 1 B 1 C 1 A 2 B 2 C 2 A 3 B 3 C 3 A4 B 4 and C 4 They are the same, usually each being CH. Preferably, each R n They are all methyl groups.

[0286] A preferred ligand of formula (XI) is TM23PyPz, which has formula (XI-a):

[0287]

[0288] It should be understood that, among the polydentate ligands of formulas (IB), (II-B), (VB), (VC), (VII-B), and (VIII-B), each containing a bridge, the resulting polydentate ligand is capable of chelating two iron or manganese ions. Such polydentate ligands, as well as other polydentate ligands described herein, can be readily obtained by those skilled in the art.

[0289] For example, with respect to ligands of formula (IB), those skilled in the art will recognize that, for instance, if Q = 1,3-propylidene (-CH2CH2CH2-), the desired bridging bispidon ligand, as described by K. Born et al. (J. Biol. Inorg. Chem., 12, 36-48 (2007)), can be obtained by reacting a suitable piperidone precursor, formaldehyde, and 1,3-diamino-propane.

[0290] Regarding the ligand of formula (II-B), the synthesis of bridged triazacyclononane (TACN) compounds is described with reference to the procedure described by KO Schaefer et al. (J. Am. Chem. Soc., 120, 131040-13120 (1998)).

[0291] Regarding ligands of formula (VB), those skilled in the art will recognize that, for example, N-(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine (N3py) (whose synthesis is described by G. Roelfes et al. (J. Am. Chem. Soc., 122, 11517-11518 (2000)) can react with, for example, 1,2-dibromoethane to produce 1,2-bis(N-(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine)-ethane, similar to the synthesis of TACN bridging ligands described by KO Schaefer et al. (ibid.) or the procedure described by MKlopstra et al. (Eur. J. Inorg. Chem., 846-856 (2000)) involving the reaction of N3py with benzyl chloride to produce benzyl-N3py.

[0292] Regarding ligands of formula (VC), those skilled in the art will recognize that, for example, N-methyl-N-(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine (MeN3py) (the synthesis of which is described by M Klopstra et al. (ibid.)) can be reacted with BuLi at low temperature and then with, for example, dibromoethane to generate a bridged ligand, similar to the synthesis of MeN4py and benzyl N4py described elsewhere (see, for example, EP0909809B).

[0293] Regarding the ligand of formula (VII-B), those skilled in the art will recognize that, for example, N,N'-bis(2-pyridylmethyl)ethylenediamine (prepared as described by L Xu et al. (Inorg. Chem., 39, 5958-5963 (2000)) can react with, for example, 1,3-dibromopropane (similar to the synthesis of TACN-bridged ligands described by KO Schaefer et al. (ibid.)) to generate 1,3-bis(N,N'-bis(2-pyridylmethyl)ethylenediamine)-propane. Subsequently, methylation can be performed to obtain the methylated ligand, namely 1,3-bis(N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)ethylenediamine)-propane, similar to the synthesis of MeN3py by M Klopstra et al. (ibid.).

[0294] In cases where a polyamine-based ligand of formula (VII-B) is required (i.e., where n ≥ 1) (where each R1 group according to formula (VII-B) = pyridin-2-ylmethyl), those skilled in the art will understand that, in such cases, a suitable polyamine precursor (e.g., 1,4,7,10-tetraazadecane) can be reacted with pyridinemethyl chloride, as described in numerous articles (see, for example, L Xu et al. (Inorg. Chem., 39, 5958-5963 (2000)) to produce N,N,N',N'',N''',N'''-penta(pyridin-2-ylmethyl)-1,4,7,10-tetraazadecane). Those skilled in the art can obtain various arrangements according to formula (VII) with the number of other R1 groups or aromatic amine groups.

[0295] Regarding the ligands of formula (VIII-B), those skilled in the art will recognize that, for example, 2,11-diaza[3.3](2,6-pyridinecycloadenosine) (see WO 99 / 065905 A1) can react with 1,2-dibromoethane (similar to the synthesis of the TACN-bridging ligand described by KO Schaefer et al. (ibid.)) to produce 1,2-bis(2,11-diaza[3.3](2,6-pyridinecycloadenosine)ethane. Subsequently, methylation can be performed to obtain the methylated ligand, namely 1,2-bis(11-methyl-2,11-diaza[3.3](2,6-pyridinecycloadenosine)ethane, similar to the synthesis of MeN3py by M Klopstra et al. (ibid.).

[0296] The ligands of formula (IX) can be prepared by reacting a suitable amine-based precursor with, for example, dibromo-ethane via a procedure outlined above for different bridging ligands. However, they can also be prepared by reacting a suitable free polyamine precursor with, for example, pyridine carboxyl chloride via an established procedure for coupling pyridine carboxyl chloride with a free amine (see several references to examples given in the patent application).

[0297] It should be understood that the procedures outlined above can be modified to the extent that those skilled in the art can normally adapt them to obtain other polydentate ligands of formulas (IB), (II-B), (VB), (VC), (VI-B), (VII-B), (VIII-B), and (IX), and the alternative synthetic procedures will be obvious to those skilled in the art.

[0298] Although polydentate ligands of formulas (IB), (II-B), (VB), (VC), (VI-B), (VII-B), (VIII-B), and (IX) have been discussed, the polydentate ligands of the present invention are generally capable of chelating an iron or manganese ion, and therefore, among the chelating agents described above, chelating agents selected from the group consisting of ligands of formulas (I), (II), (III) (including (III-A)), (IV), (V), (VI), (VII), (VIII) (including (VIII-A)) and (IX) are typical.

[0299] In some embodiments, the chelating agent is selected from formulas (I), (II), (II-B), (III), (IV), (V), (VB), (VI), and (VII). Typically, the chelating agent is selected from formulas (I), (II), (IV), (V), (VB), (VI), and (VII).

[0300] In some embodiments, the chelating agent is selected from the group consisting of: 2,4-di-(2-pyridinyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate, 2,4-di-(2-pyridinyl)-3-(pyridin-2-ylmethyl)-7-methyl-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate, 9,9-dihydroxy-3-methyl-2,4-di-(2-pyridinyl)-7-(1-(N,N-dimethylamine)-ethyl-2-yl)-3,7-diaza-bicyclo[3.3.1]nonane-1,5-dicarboxylate, 2,4-di-(2- (Pyridyl)-3,7-dimethyl-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylic acid dimethyl ester, N,N-bis(pyridin-2-yl-methyl-1,1-bis(pyridin-2-yl)-1-aminoethane, N-methyl-N-(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine, N-benzyl-N-(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine, N-methyl-N,N',N'-tris(pyridin-2-ylmethyl)ethylenediamine, N-butyl-N,N',N'-tris(pyridin-2-ylmethyl)-1,2-ethylenediamine, N-octyl-N,N',N'-tris(pyridin-2-ylmethyl)-1,2-ethylenediamine, N, N, N', N'-Tetra(pyridin-2-yl-methyl)ethylene-1,2-diamine, N, N, N', N'-Tetra(benzimidazol-2-ylmethyl)ethylene-1,2-diamine, Tris(pyridin-2-ylmethyl)amine, 1,4,7,10-Tetra(2-pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane, 1-Methyl-4,7-bis(pyridin-2-ylmethyl)-1,4,7-triazacyclononane, 1-Methyl-4,7-bis(quinoline-2-ylmethyl)-1,4,7-triazacyclononane, 1-Ethyl-4,7-bis(quinoline-2-ylmethyl)-1,4,7-triazacyclononane, 2,6-bis(pyridin-2-ylmethyl)-1,1,7,7- Tetra(pyridin-2-yl)-2,6-diazaheptane, 2,6-bis(pyridin-2-ylmethyl)-1,1,7,7-tetra(pyridin-2-yl)-2,6-diazaheptane (N,N'-bis(dipyridin-2-ylmethyl)-N,N'-bis(pyridin-2-ylmethyl)-1,3-diamino-propane), 1,4,7-trimethyl-1,4,7-triazacyclononane, 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane and 5,10,15,20-tetra(4-pyridinyl)-21H,23H-porphyrin tetra(methyl chloride).

[0301] In a particular embodiment, the chelating agent is selected from the group consisting of: 2,4-di-(2-pyridinyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylic acid dimethyl ester, N,N-bis(pyridin-2-yl-methyl-1,1-bis(pyridin-2-yl)-1-aminoethane, N-methyl-N,N',N'-tris( Pyridin-2-ylmethyl)ethylenediamine, tris(pyridin-2-ylmethyl)amine, 1,4,7,10-tetra(2-pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane, 1-ethyl-4,7-bis(quinoline-2-ylmethyl)-1,4,7-triazacyclononane and 2,6-bis(pyridin-2-ylmethyl)-1,1,7,7-tetra(pyridin-2-yl)-2,6-diazaheptane.

[0302] In a more specific embodiment, the chelating agent is selected from the group consisting of: 2,4-di-(2-pyridinyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diazabicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate, N,N-bis(pyridin-2-yl-methyl-1,1-bis(pyridin-2-yl)-1-aminoethane, N-methyl-N,N',N'-tris(pyridin-2-ylmethyl)ethylenediamine, tris(pyridin-2-ylmethyl)amine and 2,6-bis(pyridin-2-ylmethyl)-1,1,7,7-tetra(pyridin-2-yl)-2,6-diazaheptane.

[0303] In a particular embodiment, the chelating agent is dimethyl 2,4-di-(2-pyridinyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate.

[0304] As described herein, the iron or manganese complexes mentioned in various aspects of the invention are formed by chelating agents (including specific examples of such ligands described in detail herein) capable of chelating at least one iron or manganese ion by at least three nitrogen atoms. These ligands contain donor atoms that are coordinated with one or more iron or manganese ions of the iron or manganese complexes described herein.

[0305] The concentration of iron or manganese complexes in the aqueous media described herein is typically from about 0.001 to about 50 μM, usually from about 0.01 to about 20 μM, and according to a particular embodiment, from about 0.03 to about 5 μM.

[0306] It should be understood that although complexes can be incorporated into the methods of the first and third aspects of the invention, and the aqueous medium according to the second aspect of the invention can be prepared by such complexes (which we refer to herein as the explicitly defined complexes) themselves, the explicitly defined complexes are not an essential feature of the invention.

[0307] A explicitly defined complex herein (as the term is commonly used in the art) means a pre-formed complex (i.e., not an in-situ prepared complex) that has been isolated or can be isolated such that it is readily characterized (i.e., defined) and analyzed (e.g., to determine its structure and purity). In contrast, an undefined complex is an in-situ prepared complex that has not been isolated from the medium in which the complex is prepared (e.g., the reaction medium) and is optionally used. Explicitly defined complexes are not a mandatory feature of this invention; however, suitable iron or manganese complexes can be prepared by mixing an appropriate amount of a multidentate ligand with an appropriate amount and source of iron or manganese ions in the desired stoichiometric ratio.

[0308] It should be understood that there are no particular restrictions on the source of iron or manganese ions (from which the iron or manganese complexes described herein can be prepared).

[0309] Typically, iron salts are selected from the group consisting of: optionally hydrated FeCl2, FeBr2, Fe(NO3)2, FeSO4, Fe(CF3SO3)2, Fe(acetylacetone)2, Fe(acetylacetone)3, Fe(R5COO)3 (including Fe(acetate)3), and Fe(R5COO)2 (where R5 is selected from C1-C). 24 Alkyl groups). In cases where the salt contains more than two R5 groups, these groups may be the same or different. The alkyl portion of the saturated hydrocarbon group may be straight-chain or include branched and / or cyclic portions. Typically, iron salts are selected from the group consisting of: optionally hydrated FeCl2, FeBr2, Fe(NO3)2, FeSO4, and Fe(OAc)2.

[0310] Typically, manganese salts are selected from the group consisting of: optionally hydrated MnCl2, MnBr2, Mn(NO3)2, MnSO4, Mn(acetylacetone)2, Mn(acetylacetone)3, Mn(R5COO)3 (including Mn(acetate)3), and Mn(R5COO)2 (where R5 is selected from C1-C). 24Alkyl groups). In cases where the salt comprises more than two R5 groups, these groups may be the same or different. This means that the alkyl portion of the saturated hydrocarbon group may be straight-chain or include branched and / or cyclic portions. Typically, manganese salts are selected from the group consisting of: optionally hydrated MnCl2, MnBr2, Mn(NO3)2, MnSO4, and Mn(OAc)2.

[0311] The term "optionally hydrated" is well known in the art. Metal salts typically contain water molecules within their crystal lattice, which remain unless a specific drying step is performed on the hydrated metal salt by heating or drying under reduced pressure. However, partially or completely dehydrated metal salts may also be used. For example, ferric chloride(II), manganese acetate(II), and manganese chloride(II) are available as tetrahydrates or as dehydrated (anhydrous) salts. Commercially available ferric sulfate is available in dehydrated (anhydrous), monohydrate, and heptahydrate forms. Commercially available manganese sulfate is available in both tetrahydrate and monohydrate forms.

[0312] The term "about" in this document, when modifying numbers or values, refers to values ​​within ±5% of the specified value. For example, if pH is specified as about 1 to about 3.5, then pH values ​​from 0.095 to 3.675 are included.

[0313] According to a particular embodiment of the invention, the complexes used in the first and third aspects of the invention, or the complexes present in the compositions of the second and fourth aspects of the invention or the kits of the seventh aspect of the invention, are pre-formed (used interchangeably herein with the term "expressly defined"). Typically, it is desirable to use pre-formed iron or manganese complexes.

[0314] The iron or manganese complexes used in various aspects of the present invention typically have the general formula (A1):

[0315] [M a L k X n ]Y m (A1)

[0316] in:

[0317] M represents iron ions selected from Fe(II), Fe(III), Fe(IV) and Fe(V), or manganese ions selected from Mn(II), Mn(III), Mn(IV) and Mn(V);

[0318] L represents one or more polydentate ligands as defined in this article, or their protonated or deprotonated derivatives;

[0319] Each X independently represents a coordination species selected from any monocharged, dicharged, or tricharged anion or a neutral molecule capable of coordinating with iron or manganese ions in a monodentate, bidentate, or tripentate manner, preferably selected from O. 2- RBO2 2- RCOO - RCONR - OH - NO3 - NO, S 2- RS - PO4 3- PO3OR 2- H2O, CO3 2- HCO3 - ROH, N(R)3, ROO - O2 2- O2 - , RCN, Cl - ,Br - OCN - SCN - CN - N3 - F - I - RO - ClO4 - and CF3SO3 - And more preferably selected from O 2 RBO2 2- RCOO - OH - NO3 - S 2- RS - PO4 3- HPO4 2- H2O, CO3 2- HCO3 - ROH, N(R)3, Cl - ,Br - OCN - SCN - , RCN, N3 - F - I - RO - ClO4 - and CF3SO3 - ;

[0320] Each R independently represents a group selected from hydrogen, hydroxyl, -R”, and –OR”, where R” = C1-C 20 Alkyl, C2-C20 alkenyl, C1-C 20 Heterocyclic alkyl, C6-C 10 Aryl, C5-C 10 heteroaryl, (C=O)H, (C=O)-C1-C 20 Alkyl, (C=O)-C6-C 10 Aryl, (C=O)OH, (C=O)O-C1-C 20 Alkyl, (C=O)O-C6-C 10 Aryl, (C=O)NH2, (C=O)NH(C1-C 20 Alkyl), (C=O)NH(C6-C) 10 Aryl), (C=O)N(C1-C 20 Alkyl)2、(C=O)N(C6-C 10 Aryl(R)2, R” is optionally replaced by one or more functional groups E, wherein E independently represents a functional group selected from: -F, -Cl, -Br, -I, -OH, -OR', -NH2, -NHR', -N(R')2, -N(R')3 + , -C(O)R', -OC(O)R', -COOH, -COO - (Na + K + -COOR', -C(O)NH2, -C(O)NHR', -C(O)N(R')2, heteroaryl, -R', -SR', -SH, -P(R')2, -P(O)(R')2, -P(O)(OH)2, -P(O)(OR')2, -NO2, -SO3H, -SO3-(Na) + K + -S(O)2R', -NHC(O)R' and -N(R')C(O)R', where R' represents C6-C 10 Aryl, C7-C 20 Arylalkyl or C1-C 20 Alkyl groups, each of which may optionally be prefixed with -F, -Cl, -Br, -I, or -NH3. + -SO3H, -SO3 - (Na + K + -COOH, -COO - (Na + K + -P(O)(OH)2 or -P(O)(O - (Na + K + ))2 substitution, and preferably each R independently represents hydrogen, C1-C 40Alkyl or optionally C1-C 20 Alkyl-substituted C6-C 10 Aryl, more preferably hydrogen or optionally substituted phenyl or naphthyl, or C 1-4 alkyl;

[0321] Y is a noncoordinate counter ion;

[0322] a is an integer from 1 to 10, typically from 1 to 4, and still more typically from 1 or 2;

[0323] k is an integer from 1 to 10, typically from 1 to 4, and still more typically from 1 or 2;

[0324] n is an integer from 1 to 10, typically from 1 to 4; and

[0325] m is zero or an integer from 1 to 20, and typically an integer from 1 to 8.

[0326] Typically, one or more iron ions in the complex are selected from the group consisting of Fe(II), Fe(III), and Fe(IV), and one or more manganese ions in the complex are selected from the group consisting of Mn(II), Mn(III), and Mn(IV). Usually, the complex contains one or two such iron or manganese ions. In the case where the complex contains more than two iron or manganese ions, they may have the same oxidation state or different oxidation states. Additionally, in the case where the complex contains two metal ions, one metal ion may be iron, and the second metal ion may be manganese.

[0327] As used herein, within the definitions provided above with respect to equation (A1) and elsewhere, the following definitions apply unless the context explicitly states otherwise:

[0328] Alkyl groups, as used herein, refer to saturated hydrocarbon groups, which can be straight-chain, cyclic, or branched. Alkylenes refer to alkyl groups that have been formally stripped of a hydrogen atom. Typically, alkyl and alkylene groups will contain 1 to 25 carbon atoms, more usually 1 to 10 carbon atoms, and still more usually 1 to 6 carbon atoms. The simplest alkylene is methylene (-CH2-).

[0329] Alkenyl refers to an unsaturated hydrocarbon group containing one or more (typically one) non-aromatic carbon-carbon double bonds, which can be straight-chain, cyclic, or branched. Alkenyl refers to an alkenyl group that has formally lost a hydrogen atom. Typically, alkenyl and alkenyl groups will contain 2 to 25 carbon atoms, more usually 2 to 10 carbon atoms, and still more usually 2 to 6 carbon atoms. The simplest alkenyl group is vinylidene (-CH=CH-).

[0330] • Alynyl group refers to an unsaturated hydrocarbon group containing one or more (typically one) carbon-carbon triple bonds, which can be straight-chain, cyclic, or branched. • Alynyl group refers to an alkynyl group that has formally lost a hydrogen atom. Typically, both alkynyl and ynylyl groups will contain 2 to 25 carbon atoms, more usually 2 to 10 carbon atoms, and still more usually 2 to 6 carbon atoms.

[0331] The term "aromatic" as used herein encompasses "hybrid aromatics" within its scope. As is known to those skilled in the art and as used herein, a heteroaromatic moiety can be considered as a subset of an aromatic moiety comprising one or more heteroatoms (typically oxygen, nitrogen, or sulfur) replacing one or more cyclic carbon atoms and any hydrogen atoms attached thereto. Examples of heteroaromatic moiety include, for example, pyridine, furan, pyrrole, and pyrimidine.

[0332] • The aromatic moiety can be polycyclic, meaning it includes two or more fused aromatic (including heterocyclic) rings. Naphthalene and anthracene are examples of polycyclic aromatic moieties, and benzimidazole is an example of a polycyclic heterocyclic aromatic moiety.

[0333] Aryl groups and aryl-dimethyl groups are formed formally by abstracting one and two hydrogen atoms from the aromatic moiety, respectively. Therefore, phenyl and phenylene are the aryl group and aryl-dimethyl group corresponding to benzene, respectively. Similarly, pyridyl and pyridylene (synonymous with pyridinyl) are the heteroaryl group and heteroaryl-dimethyl group corresponding to pyridine, respectively. Unless the context otherwise states, pyridyl and pyridylene are typically 2-pyridyl and pyridin-2,6-dimethyl, respectively.

[0334] Heterocyclic alkanes refer to cycloalkanes in which one or more of the CH2 moiety is replaced by heteroatoms (typically selected from the group consisting of nitrogen, oxygen, and sulfur), typically C 5-6 Cycloalkanes. In the case where the heteroatom is nitrogen, it should be understood that the CH2 moiety is formally replaced by NH rather than N. Heterocyclic alkyl groups, as used herein, refer to groups formed formally by abstracting a hydrogen atom from a heterocyclic alkane. Typical examples of heterocyclic alkyl groups are those formed formally by abstracting a hydrogen atom from a nitrogen atom. Typical heterocyclic alkyl groups include pyrrolid-1-yl, piperidin-1-yl, and morpholin-4-yl, where the heterocyclic alkyl group is formed formally by abstracting a hydrogen atom from a nitrogen atom of the parent heterocyclic alkane.

[0335] • Arylalkyl refers to an alkyl group substituted with an aryl group. Similarly, aminoalkyl refers to an alkyl group substituted with an amino group, hydroxyalkyl refers to an alkyl group substituted with a hydroxyl group, and so on.

[0336] This article describes various alkylene bridges. Such alkylene bridges are typically, but not necessarily, straight-chain alkylene bridges. However, they can be cyclic alkylene bridges (e.g., a C6 alkylene bridge can be cyclohexene, and if so, typically 1,4-cyclohexene). In bridges that are, for example, C6-C... 10 In the case of an arylene bridge, it can be, for example, a phenylene or a corresponding arylene formed by abstracting two hydrogen atoms from naphthalene. The bridge comprises one or two C1-C3 alkylene units and one C6-C... 10 In the case of an arylene unit, such a bridge can be, for example, -CH2C6H4CH2- or -CH2C6H4-. Where present, the phenylene is typically 1,4-phenylene. It should be understood that each of these bridges can optionally be independently selected from the C1-C... 24 Alkyl (e.g., C1-C) 18 Alkyl) substitution once or multiple times, for example, once.

[0337] Carboxamide (carbamoyl) refers to a compound or group containing the functional group -N(H)C(O)-.

[0338] • Carboxylic acid esters refer to compounds or groups that contain the functional group -OC(O)-.

[0339] • Alkyl ethers refer to groups of the formula -alkylene-O-alkyl, wherein alkylene and alkyl are as defined herein.

[0340] In formula (A1), the counterion Y balances the charge z on the complex formed by one or more ligands L, one or more iron or manganese ions, and the coordinating species X. If the charge z is positive, as is the case in most cases, the iron or manganese complex contains one or more iron or manganese ions and one or more non-coordinating counterions Y. Examples of counterions Y include RCOO. - BPh4 - ClO4 - BF4 - PF6 - , RSO3 - , RSO4 - SO4 2- S2O6 2- NO3 - F - Cl - ,Br - Or I - Where R is hydrogen, C1-C 40 Alkyl or optionally C1-C 20 Alkyl-substituted C6-C 10 Aryl.

[0341] However, the specific identity of one or more counterions Y is not an essential feature of this invention. Suitable counterions Y include those that lead to the formation of a storage-stable solid. When z is positive, the counterions (including those used for preferred metal complexes) are generally selected from Cl. - ,Br - I - NO3 - ClO4 - PF6 - , RSO3 - SO4 2- , RSO4 - CF3SO3 - and RCOO - In this context, R is selected from H and C. 1-12 Alkyl and optionally C 1-6 Alkyl-substituted C6H5 (i.e., where C6H5 is replaced by C) 1-6 Alkyl substitution once or multiple times (e.g., once; typically C6H5 is unsubstituted). These will typically be selected from Cl... - NO3 - PF6 - Toluenesulfonate, SO4 2- CF3SO3 - Acetate and benzoate. In particular, these will typically be selected from Cl... - NO3 - SO4 2- The group consisting of acetate ions.

[0342] When z is negative, suitable counterions include alkali metal ions, alkaline earth metal ions, and (alkyl)ammonium cations (such as tetracarbonyl ions) used for the charge of compounds based on stoichiometric equilibrium. 1-4 Alkylammonium cations), tetraarylphosphonium cations, and bis(triphenylphosphine)-ammonium cations. Tetraarylphosphonium cations include, for example, tetraphenylphosphonium ions, or related ions having four aryl or four alkyl groups on a phosphorus atom, including any combination of aryl or alkyl groups on the same phosphorus atom (including mixed aryl and alkyl groups). Tetraalkylammonium ions can include, for example, tetraethylammonium ions, tetrapropylammonium ions, and tetrabutylammonium ions, as well as those having a longer (e.g., C10) shape. 5-24 Tetraalkylammonium ions of straight-chain alkyl groups, including ammonium ions having combinations of straight-chain alkyl groups, or having four branched alkyl groups, or a mixture of branched and straight-chain alkyl groups. If z is negative, the preferred counter ions are those of alkali metal ions or alkaline earth metal ions, wherein Na... + K + and Li + It is a particularly preferred choice.

[0343] Complexes containing chelating agents capable of chelating at least one iron or manganese ion via at least three nitrogen atoms are typically mononuclear iron or manganese complexes containing other monodentate ligands (X according to formula (A1)). Examples of suitable monodentate ligands include chloride, bromide, or trifluoromethanesulfonate (CF3SO3) ions. - Anions. If, for example, an iron(II) or manganese(II) species is used with a chelating agent capable of chelating at least one iron or manganese ion through four neutral nitrogen atoms, the two monodentate ligands of the monoanions will neutralize the charge of the iron or manganese ions, and there will be no other non-coordinate counterions. However, if an iron(III), manganese(III), iron(IV), or manganese(IV) species is formed, there will be other counterions X, such as those defined in formula (A1), with chloride, trifluoromethanesulfonate, or hexafluorophosphate being the most preferred. Other possible options are conceivable, such as a neutral tripentate nitrogen donor bound to an iron(III) or manganese(III) species, wherein the three monodentate anionic ligands (such as chloride, bromide, or trifluoromethanesulfonate) make the charge of the complex zero.

[0344] In addition to anionic counterions, neutral monodentate ligands (such as acetonitrile or water) can bind to one or more iron or manganese ions. It should be understood that this possible option can also produce charged iron or manganese complexes (i.e., with bound Fe(II) or Mn(II) ions), and thus result in the presence of noncoordinate counterions. This discussion presupposes iron or manganese ions bound to six donor atoms. While this is generally the case, it is not always: for example, it is known that in addition to 6-coordinate complexes, Fe(II), Mn(II), Fe(III), or Mn(III) ions also produce 4, 5, or 7-coordinate complexes.

[0345] Complexes of formula (A1) typically contain one or two iron or manganese ions.

[0346] For binuclear iron or manganese complexes (i.e., iron or manganese complexes containing two iron or manganese ions), bridging ion ligands are typically present, that is, bridging ion ligands other than the bichelate polydentate ligands described herein. Examples of such additional bridging ligands include oxygen ions (O... 2- ), hydroxide ions (OH) - ) or C 1-6 Carboxylate group (i.e., where R is C) 1-5 alkyl RCO2 - An alkylcarboxylate ion, which bridges two iron or manganese ions. In the presence of these ions, the alkylcarboxylate ion is typically an acetate ion. Typically, binuclear complexes contain two bridging ions, for example, two acetate ions.

[0347] In particular embodiments, the iron or manganese complexes used according to various aspects of the invention are selected from the group consisting of: [Fe(2,4-di-(2-pyridinyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate)Cl]Cl, [Fe(N,N-bis(pyridin-2-yl-methyl-1,1-bis(pyridin-2-yl)-1-aminoethane)Cl]Cl, [Fe(N-methyl-N,N',N'- Tris(pyridin-2-ylmethyl)ethylenediamine)Cl]Cl, [Fe2(µ-O)(µ-CH3CO2)(tris(pyridin-2-ylmethyl)amine)2](ClO4)3, [Fe(1,4,7,10-tetra(2-pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane)](ClO4)2, [Fe(II)(1-ethyl-4,7-bis(quinoline-2-ylmethyl)-1,4,7-triazacyclononane)Cl]ClO4, [Fe2(µ-O)(µ-CH3COO] 2,6-bis(pyridin-2-ylmethyl)-1,1,7,7-tetra(pyridin-2-yl)-2,6-diazaheptane](ClO4)4, [Mn(4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane)Cl2, [Mn2(μ-O)2(μ-CH3COO)(1,2-bis-(4,7-dimethyl-1,4,7-triazacyclononane-1-yl)-ethane)]Cl2, [Mn2(μ-O)(μ-CH3COO)2(1,4,7-trimethyl-1,4,7-triazacyclononane)2](PF6)2 and 5,10,15,20-tetra(4-pyridinyl)-21H,23H-porphyrin chloride Mn(III)tetra(methyl chloride).

[0348] In even more particular embodiments, the iron or manganese complexes used according to various aspects of the invention are selected from the group consisting of: [Fe(2,4-di-(2-pyridinyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate)Cl]Cl, [Fe(N,N-bis(pyridin-2-yl-methyl-1,1-bis(pyridin-2-yl)-1-aminoethane)Cl]Cl, [Fe(N-methyl-N,N',N' -Tris(pyridin-2-ylmethyl)ethylenediamine)Cl]Cl, [Fe2(µ-O)(µ-CH3CO2)(tris(pyridin-2-ylmethyl)amine)2](ClO4)3, [Fe(1,4,7,10-tetra(2-pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane)](ClO4)2, [Fe(II)(1-ethyl-4,7-bis(quinoline-2-ylmethyl)-1,4,7-triazacyclononane)Cl]ClO4, [Fe2(µ-O)(µ-CH3COO) 2,6-bis(pyridin-2-ylmethyl)-1,1,7,7-tetra(pyridin-2-yl)-2,6-diazaheptane](ClO4)4.

[0349] In a more particular embodiment, the iron or manganese complex used according to various aspects of the invention is selected from the group consisting of: [Fe(2,4-di-(2-pyridinyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate)Cl]Cl, [Fe(N,N-bis(pyridin-2-yl-methyl-1,1-bis(pyridin-2-yl)-1-aminoethane)Cl]Cl, [Fe(N-methyl-N,N',N'-tris(pyridin-2-ylmethyl)ethylenediamine)Cl]Cl, [Fe2(µ-O)(µ-CH3CO2)(tris(pyridin-2-ylmethyl)amine)2](ClO4)3 and [Fe2(µ-O)(µ-CH3COO] 2,6-Bis(pyridin-2-ylmethyl)-1,1,7,7-tetra(pyridin-2-yl)-2,6-diazepane](ClO4)4.

[0350] Although one or more noncoordination counterions (corresponding to Y in formula (A1)) and one or more additional coordination stabilizing ligands (corresponding to X in formula (A1)) are specified in the above embodiments, they are not limited to those specified and can be readily exchanged for other one or more noncoordination counterions and one or more coordination stabilizing ligands, as described above with respect to Y and X in formula (A1). For example, chloride counterions can be exchanged for PF6 counterions, and / or chloride coordination stabilizing ligands can be exchanged for coordination water ligands.

[0351] The matrix according to the third aspect of the invention is not particularly limited and can be any matrix that is desired to be treated with chlorine dioxide. According to some embodiments, the matrix is ​​a polysaccharide or contains polysaccharides, such as cellulose or starch, typically cellulose. An example of a particularly important embodiment in this aspect is the treatment of wood pulp. However, a wide variety of other matrices can be treated according to the invention. For example, the invention is widely used for treating food, including but not limited to fruits, vegetables, meat, and fish; for treating hard surfaces, including but not limited to sanitary conditions of livestock processing equipment and livestock habitats; and for treating biofilms.

[0352] In many of these applications, the aim is sterilization: by processing food, such as, but not limited to, fruits, vegetables, meat and fish; hard surfaces, such as those on equipment used in food processing (including livestock processing), medical or laboratory equipment and equipment used in livestock farming; and biofilms, such as biofilms on membranes, the aim is usually to achieve sterilization to eradicate or treat microorganisms, such as viruses, bacteria and protozoa.

[0353] In this paper, the IUPAC definition of biofilm (Pure Appl. Chem., 84(2), 377-410(2012)) is adopted, which is an aggregate of microorganisms in which cells, typically embedded in a matrix of self-generated extracellular polymeric material, adhere to each other and / or adhere to a surface. Biofilms are commonly found on membranes present in all types of filtration devices. All such membranes are susceptible to fouling by biofilms, particularly those found in reverse osmosis systems. Therefore, treatment of biofilm-prone matrices is a particularly useful embodiment of the present invention: biofilm prevention and / or treatment reduce the need for maintenance and cleaning, thereby resulting in lower maintenance and system operating costs. Like membrane devices, devices susceptible to biofilm formation include, but are not limited to: tubing; cleaning (including laundry, dishwashing, and bathing) equipment such as pools, bathtubs, shower rooms, dishwashers, and washing machines, including their surfaces (e.g., shower room walls and floors); cooling and heating systems; and marine equipment (including the hulls of ships and vessels). Typically, biofilms form in environments with frequent or prolonged contact with water. However, it should be understood that this is not necessarily the case, and biofilm formation is an important issue in the oil and gas industry (e.g., in pipelines and other production facilities).

[0354] Therefore, it should be understood that the third aspect of the invention has particular commercial applicability in the treatment or prevention of biofilms, the method comprising treating any substrate on which biofilms may be present, such as the device mentioned in the preceding paragraph.

[0355] In addition to treating or preventing biofilm, the present invention can also be used to control microorganisms in water. Therefore, it should be understood that the second aspect of the invention also has particular commercial applicability in water treatment. In this context, it should be understood that the method according to the third aspect of the invention provides a method for treating water, comprising contacting water with a certain amount of chlorite and a complex as defined herein.

[0356] There are no limitations on the water that can be treated according to the present invention. It can be, for example, water in municipal, commercial, industrial and domestic water systems, including drinking water, treated water from factories, cooling water, or water present in swimming pools, boilers, conditioning equipment or other industrial treated water.

[0357] Although the following discussion focuses on the treatment of cellulose matrices and, in particular, wood pulp (reflecting the commercial reality of most chlorine dioxide applications), it should be understood that this discussion is not limiting, and the invention, with necessary modifications, is suitable for the treatment of other polysaccharide-containing matrices and, in fact, the treatment of water as described herein.

[0358] According to various embodiments of the invention, the matrix processed according to a third aspect of the invention is a polysaccharide or contains polysaccharides. Within the scope of polysaccharide-containing matrices, cellulose (i.e., cellulose-containing) matrices are commercially particularly important. Cellulose matrices primarily include wood pulp and cotton (and therefore cotton-containing materials), as well as other plant-derived materials such as bagasse and jute fiber. The processing of cellulose matrices is therefore widespread, with the bleaching of both wood pulp and cotton being large-scale industries, including the processing of raw cotton in the cotton processing industry and in laundry (domestic, industrial, and institutional). In each case, the purpose of the treatment is to bleach these matrices, which means the oxidative removal of undesirable contaminants. In the processing of raw cotton and wood pulp (and other plant-derived materials), these contaminants are typically polyphenolic materials, as well as lignin, which constitutes a large proportion of wood (responsible for the dark color of unbleached wood pulp). In laundry applications, undesirable contaminants specifically targeted for bleaching include those that cause soiling.

[0359] To produce high-quality paper grades, wood pulp needs to be delignified and bleached to a degree sufficient to produce white pulp that is also stable against light-induced and time-induced yellowing / aging. Typically, wood is milled, pulped, and then treated at high temperatures with alkaline sulfates or sulfites to remove most of the lignin. Pulp treated in this way is often referred to as chemical pulp.

[0360] An overview of the uses of chlorine dioxide (and other bleaching agents) in wood pulp treatment can be found in Pulp Bleaching, Principles and Practice (CW Dence and DW Reeve, ed., Tappi, 1996).

[0361] Typically, in the first step, an oxygen delignification process is performed to remove approximately half of the lignin remaining in the chemical pulp. This partially delignified pulp is then usually treated separately with chlorine dioxide and hydrogen peroxide. Depending on the type of wood and the desired paper quality (brightness), up to two to three separate steps using chlorine dioxide and one to two stages using hydrogen peroxide are performed. Alternatively, delignified and bleached pulp is often produced without the use of any chlorine-based bleaching chemicals, resulting in so-called total chlorine-free (TCF) pulp.

[0362] In the first step, following the oxygen delignification step, chlorine dioxide is primarily used as the delignifying agent (D0- stage). In some cases, elemental chlorine is also used as a bleaching chemical, which, when combined with chlorine dioxide, provides good activity. The application of chlorine alone (i.e., chlorine dioxide is not used) is no longer implemented, as this leads to the formation of undesirable large amounts of chlorinated waste products. In the later stages of the pulp bleaching process (D1 or D2 stages), chlorine dioxide is mainly used for further bleaching of pulp containing small amounts of lignin residue.

[0363] The loading of chlorine dioxide in pulp mills is typically from about 2% to about 10% by weight (relative to oven-dry pulp), where processing takes place at about 40–100°C. The duration of delignification varies, but is typically less than 1 hour to 4 hours.

[0364] It should be understood that various aspects of the present invention are applicable in every step of the wood pulping process in which chlorine dioxide can be used (e.g., those described above).

[0365] As described above, the concentration of chlorite in the aqueous medium described herein is from about 0.1 to about 50 mM, for example from about 5 to about 30 mM. Those skilled in the art will be able to optimize the amount required to achieve the appropriate level of bleaching or delignification of the wood pulp. The concentration of bleaching chemicals (such as chlorine dioxide) is most commonly expressed in the context of pulp bleaching as kilograms (kg) per tonne dried pulp (odp). Typical concentrations of chlorine dioxide currently used are from about 5 to about 20 kg / tonne odp. If the pulp is bleached at a 10% consistency level (meaning 100 g / kg odp in the bleaching solution), the concentration of ClO2 will be from about 0.5 to about 2 g / L (which, based on molar concentration, is equal to about 7.4 to about 29.4 mM). However, it should be understood that the amount of chlorite used according to the invention can be lower than these while still maintaining the desired degree of bleaching. Of course, those skilled in the art will be able to determine the appropriate amount of chlorite for any given method.

[0366] Typically, in the case of water treatment using the method of the third aspect of the invention, the composition of the second aspect is added to an aqueous solution containing the water to be treated, for example, to achieve antimicrobial activity or to prevent the formation of biofilm substances. While the resulting solution may contain very low levels of chlorine dioxide, such as 1-30 mg / L, the compositions of the present invention (such as those of the second aspect) may contain significantly higher levels of chlorine dioxide, such as 100-5000 mg / L. Typically, the composition of the second aspect will contain about 300 to about 3000 mg / L of chlorine dioxide, the latter value determined by the solubility of chlorine dioxide in water at 25°C. At lower temperatures, the solubility of chlorine dioxide in water is higher. However, typically about 3000 mg ClO2 / L of water is prepared. Those skilled in the art will be able to determine the appropriate amount of chlorine dioxide or chlorite for any given method.

[0367] Another advantage of the invention, particularly but not limited to the context of wood pulp processing, stems from the reaction between hypochlorite and chlorite to form chloride and chlorine dioxide. In the case of an aqueous medium (e.g., a solution) containing chlorite, it will react with any hypochlorite that can be formed following the reaction of chlorine dioxide with partially oxidized lignin residues (see Pulp Bleaching, Principles and Practice, CW Dence and DW Reeve, ed., Tappi, 1996, pp. 133-138). Hypochlorite as a byproduct is less desirable because it can react with lignin residues to form chlorinated phenols. However, as a strong oxidizing agent, hypochlorite reacts very efficiently with chlorite to form chloride and chlorine dioxide (see Z Jia et al., Inorg. Chem., 39(12), 2614–2620 (2000)), and thus will cause the present chlorite to react, thereby preventing hypochlorite from reacting further to form chlorinated byproducts.

[0368] When used to achieve antimicrobial effects, the amount of chlorite is typically much lower than that used in pulp bleaching, typically from about 1 to about 30 mg / l. Furthermore, a skilled technician will be able to determine the appropriate amount of chlorine dioxide or chlorite for any given method.

[0369] In all the methods according to the invention, it should be understood that, in the case of using chlorite, a particular advantage is that it is not necessary to generate chlorine dioxide in situ.

[0370] The aqueous medium of the present invention has a pH of about 1 to about 3.5. The chlorite and complex of the composition of the second aspect can be contacted in an aqueous medium containing a bisulfate or oxalate buffer and having a pH of about 1 to about 3.5. Typically, the aqueous medium of the present invention has a pH of about 1 to about 3.5, more typically about 1.5 to about 3.0. The concentration of the buffer is preferably about 1 mM to about 1 M; more typically about 5 mM to about 50 mM. If, for example, a pH of 2.0 is used, the pKa of the buffer at a suitable concentration range should be 2.0 + / - 1.0 to have effective buffering capacity. Suitable buffers having low pKa values ​​(about pH 1 to about 3.5) are well known in the art and include bisulfate (HSO4). - ) and oxalic acid. The cationic counterion of the bisulfate buffer can be chosen arbitrarily; preferred cationic counterions include sodium or potassium cations. To avoid ambiguity, a suitable buffer also acts as a suitable acid.

[0371] A suitable amount of a strong acid (other than a buffer) with a pKa value less than 1 can also be used to lower the pH of the aqueous medium to the desired level. Technicians will be able to determine the required amount of acid to be added using a pH meter. Examples of suitable strong acids include sulfuric acid, hydrobromic acid, and hydrochloric acid. Furthermore, mixtures of different acids, such as a mixture of sodium bisulfate and hydrochloric acid, can be used to further lower the pH of the aqueous medium. Mixtures of different acids may be desirable compared to using hydrochloric acid alone (which has no buffering capacity at around pH 2) or using sodium bisulfate alone (where achieving a low pH may be difficult).

[0372] The temperature used to carry out the methods of this invention can be determined by those skilled in the art. For example, cellulose treatment processes can be carried out at temperatures similar to those currently implemented. Obviously, the optimal temperature will depend on the matrix and will typically be about 50 to about 70°C for wood pulp bleaching, although improved bleaching processes have been achieved by increasing the temperature, for example, for treating eucalyptus pulp. However, it should be noted that the methods described herein can achieve the same bleaching activity at temperatures lower than those achievable in the absence of the iron or manganese complexes described herein. Thus, while the temperature range currently used for wood pulp bleaching is typically about 50 to about 100°C, the use of the iron or manganese complexes described herein can allow for lower temperatures. For treatments on polysaccharide-based matrices, temperatures of about 30 to about 100°C (e.g., about 40 to about 95°C) are typical. For treatments on water or other matrices used to obtain antimicrobial effects, ambient temperatures (e.g., 15 to 30°C) are generally appropriate. Nevertheless, it should be understood that a person performing any given method can determine the exact temperature without undue burden.

[0373] Typically, the mixing of chlorite, acids containing bisulfate or bioxate with a pKa of about 1 to about 3.5, or aqueous media having a bisulfate or oxalate buffer and a pH of about 1 to about 3.5 with the iron or manganese complex of the present invention (such as complexes of formula (A1)) is carried out under ambient conditions, wherein the preferred temperature is equal to or below about 35°C. Temperatures exceeding about 35°C are preferably avoided because the solubility of chlorine dioxide in water is lower at higher temperatures (see Deshwal, W and Kundu, N, Asian J. of Chemistry, 27, 4429-4435 (2015)). For this reason, temperatures typically equal to or below about 30°C and more typically equal to or below about 25°C will be used.

[0374] The individual and every patent and non-patent document mentioned in this article are incorporated herein by reference in their entirety, just as the full content of each document is presented herein in its entirety.

[0375] The invention can be further understood by referring to the following non-limiting provisions:

[0376] Clause 1. A method for producing chlorine dioxide from chlorite, the method comprising: contacting the following in an aqueous medium:

[0377] (i) the chlorite; and

[0378] (ii) A complex comprising one or more iron ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one iron ion via at least three nitrogen atoms, provided that the one or more polydentate ligands are not porphyrin or porphyrinazine ligands; or

[0379] A complex comprising one or more manganese ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one manganese ion by at least three nitrogen atoms;

[0380] The aqueous medium contains a bisulfate or oxalate buffer and has a pH of about 1 to about 3.5.

[0381] Clause 2. The method according to Clause 1, wherein the pH is from about 1.5 to about 3.0.

[0382] Clause 3. The method according to Clause 1 or Clause 2, wherein the aqueous medium comprises a bisulfate buffer.

[0383] Clause 4. The method according to any of the preceding clauses, wherein the aqueous medium contains an acid selected from the group consisting of sodium bisulfate, potassium bisulfate, sulfuric acid, hydrochloric acid, oxalic acid, and hydrobromic acid.

[0384] Clause 5. The method according to Clause 4, wherein the acid is selected from sodium bisulfate, potassium bisulfate and hydrochloric acid.

[0385] Clause 6. The method according to any of the preceding clauses, wherein the aqueous medium comprises an alkali metal halide.

[0386] Clause 7. The method according to Clause 6, wherein the alkali metal halide is sodium chloride.

[0387] Clause 8. The method according to Clause 6 or Clause 7, wherein the aqueous medium comprises about 10 mM to about 6 M of an alkali metal halide.

[0388] Clause 9. The method according to Clause 8, wherein the aqueous medium comprises about 100 mM to about 1 M of an alkali metal halide.

[0389] Clause 10. The method according to any of the preceding clauses, wherein the aqueous medium comprises about 0.03 to about 5 μM of the complex.

[0390] Clause 11. The method according to any of the preceding clauses, wherein the method involves using chlorites selected from the group consisting of sodium chlorite, potassium chlorite, lithium chlorite, calcium chlorite, barium chlorite and magnesium chlorite.

[0391] Clause 12. The method according to Clause 11, wherein the chlorite is sodium chlorite.

[0392] Clause 13. The method according to any of the preceding clauses, wherein the complex is pre-formed.

[0393] Clause 14. The method according to any of the preceding clauses, wherein the complex comprises one or more iron ions.

[0394] Clause 15. The method according to any of the preceding clauses, wherein the complex comprises a chelating agent capable of chelating at least one iron or manganese ion by at least three nitrogen atoms, said chelating agent having the formula (I), (IB), (II), (II-B), (III), (IV), (V), (VB), (VC), (VI), (VII), (VII-B), (VIII), (VIII-B), or (IX)):

[0395]

[0396] in:

[0397] Each D is independently selected from the group consisting of: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-1-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, and thiazolyl-2-yl, each of which may optionally be substituted by one or more groups independently selected from the group consisting of: -F, -Cl, -Br, -OH, -OC1-C4 alkyl, -NH-CO-H, -NH-CO-C1-C4 alkyl, -NH2, -NH-C1-C4 alkyl, and -C1-C4 alkyl;

[0398] Each or every R1 and R2 is independently selected from the group consisting of the following items: C1-C 24 Alkyl, C 6-10 Aryl C1-C6 alkyl, C 6-10 Aryl and C5-C10 Heteroaryl C1-C6 alkyl groups, each of which may optionally be substituted with one or more groups selected from the group consisting of: -F, -Cl, -Br, -OH, -OC1-C4 alkyl, -NH-CO-H, -NH-CO-C1-C4 alkyl, -NH2, -NH-C1-C4 alkyl, and –SC1-C4 alkyl; and CH2CH2N(R10)(R11),

[0399] Where N(R10)(R11) is selected from the group consisting of the following items: two (C 1-44 alkyl)amino; di(C) 6-10 Aryl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; di(C) 6-10 Aryl C 1-6 Alkyl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; NR7, wherein R7 and the nitrogen atom N to which it is attached represent optional substitution by one or more C atoms. 1-20 Alkyl-substituted heterocyclic alkyl groups, wherein the heterocyclic alkyl group is connected to the remainder of R1 via a nitrogen atom N; bis(heterocyclic C 1-6 Alkyl)amino, wherein each of the heterocyclic alkyl groups is independently optionally constituting one or more C 1-20 Alkyl substitution; and di(heteroaryl C) 1-6 Alkyl)amino, wherein each of the heteroaryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution;

[0400] R3 and R4 are independently selected from hydrogen, C1-C8 alkyl, C1-C8 alkyl-O-C1-C8 alkyl, C6-C 10 Aryloxy C1-C8 alkyl, C6-C 10 Aryl, C1-C8 hydroxyalkyl, C6-C 10 Aryl C1-C6 alkyl and C5-C 10 Heteroaryl C1-C6 alkyl groups and -(CH2) 0-4 C(O)OR5, wherein R5 is independently selected from: hydrogen, C1-C8 alkyl, and C 6-10 Aryl;

[0401] Q2 represents selecting the bridge from the group consisting of the following items: C 1-6 alkylene moiety, C 6-10 The aryl group may contain one or two C atoms. 1-3 alkylene unit and a C 6-10 The aryl unit portion, wherein the bridge is optionally independently selected by C 1-24 Alkyl and OH groups are substituted once or multiple times; and

[0402] X is selected from C=O and -[C(R6)2] 0-3 - where each R6 is independently selected from hydrogen, hydroxyl, C1-C4 alkoxy and C1-C4 alkyl;

[0403]

[0404] in:

[0405] Each Q is independently selected from -CR4R5CR6R7- and -CR4R5CR6R7CR8R9-;

[0406] R4, R5, R6, R7, R8 and R9 are independently selected from: H, C1-C4 alkyl and hydroxy C1-C4 alkyl;

[0407] Each of R1, R2, and R3 is independently selected from the group consisting of: hydrogen, C1-C 24 Alkyl group, CH2CH2OH, CH2COOH, CH2PO3H2, C5-C 10 Heteroaryl C1-C6 alkyl groups and CH2CH2N(R10)(R11),

[0408] Where N(R10)(R11) is selected from the group consisting of the following items: two (C 1-44 alkyl)amino; di(C) 6-10 Aryl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; di(C) 6-10 Aryl C 1-6 Alkyl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; NR7, wherein R7 and the nitrogen atom N to which it is attached represent optional substitution by one or more C atoms. 1-20 Alkyl-substituted heterocyclic alkyl groups, wherein the heterocyclic alkyl group is connected to the remainder of R1 via a nitrogen atom N; bis(heterocyclic C 1-6 Alkyl)amino, wherein each of the heterocyclic alkyl groups is independently optionally constituting one or more C 1-20 Alkyl substitution; and di(heteroaryl C) 1-6 Alkyl)amino, wherein each of the heteroaryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; and

[0409] Q2 is the bridge selected from the group consisting of the following items: C 1-6 alkylene moiety, C 6-10 The aryl group may contain one or two C atoms. 1-3 alkylene unit and a C 6-10In the aryl unit portion, the bridge can optionally be independently selected by C. 1-24 Alkyl and OH groups are substituted once or multiple times;

[0410]

[0411] in:

[0412] Each -Q- is independently selected from -N(R)C(R1)(R2)C(R3)(R4)- and -N(R)C(R1)(R2)C(R3)(R4)C(R5)(R6)-;

[0413] Each -Q1- is independently selected from -N(R')C(R1)(R2)C(R3)(R4)- and -N(R')C(R1)(R2)C(R3)(R4)C(R5)(R6)-;

[0414] Each R is independently hydrogen, or selected from the group consisting of the following: C1-C 20 Alkyl, C2-C 20 alkenyl, C2-C 20 alkynyl group, C6-C 10 Aryl and C7-C 20 Arylalkyl groups, each of which may optionally be C1-C6 alkyl groups and / or C5-C6 alkyl groups. 10 Heteroaryl substitution; and CH2CH2N(R10)(R11),

[0415] Where N(R10)(R11) is selected from the group consisting of the following items: two (C 1-44 alkyl)amino; di(C) 6-10 Aryl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; di(C) 6-10 Aryl C 1-6 Alkyl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; NR7, wherein R7 and the nitrogen atom N to which it is attached represent optional substitution by one or more C atoms. 1-20 Alkyl-substituted heterocyclic alkyl groups, wherein the heterocyclic alkyl group is connected to the remainder of R1 via a nitrogen atom N; bis(heterocyclic C 1-6 Alkyl)amino, wherein each of the heterocyclic alkyl groups is independently optionally constituting one or more C 1-20 Alkyl substitution; and di(heteroaryl C) 1-6 Alkyl)amino, wherein each of the heteroaryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution;

[0416] The two –R' groups in the two Q1 groups together form the bridging portion –Q2-;

[0417] Q2 is the bridge selected from the group consisting of the following items: C 2-6 alkylene moiety, C 6-10 The arylene moiety may contain one or two C1-C3 alkylene units and one C6-C4 alkylene unit. 10 In the aryl unit portion, the bridge can optionally be independently selected by C. 1-24 Alkyl substitution once or multiple times; and

[0418] R1-R6 are each independently selected from: H, C 1-4 Alkyl and hydroxy C 1-4 alkyl;

[0419]

[0420] in:

[0421] Each -R1 is independently selected from -CH2N(C1-C 24 The heteroaryl group is selected from: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, 1,2,4-triazol-1-yl, 1,2,4-triazol-3-yl, and thiazolyl-2-yl;

[0422] Each -R2 independently represents -R4-R5;

[0423] Each -R3 and each -R6 independently represents hydrogen or a group selected from the following: C1-C6 alkyl, C6 ... 10 Aryl, C5-C 10 heteroaryl, C6-C 10 Aryl C1-C6 alkyl and C5-C 10 Heteroaryl C1-C6 alkyl groups, each of which may optionally be C1-C6 alkyl substituted;

[0424] Each -R4- independently represents a C1-C6 alkylene group that is optionally alkyl-substituted;

[0425] Each -R5 independently represents -CH2N(C1-C 24The heteroaryl group is selected from the group consisting of: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-1-yl, and thiazolyl-2-yl;

[0426] Each -NR7 independently represents where R7 and the nitrogen atom N it is attached to are optionally represented by one or more C atoms. 1-20 The alkyl-substituted heterocyclic alkyl group, wherein the heterocyclic alkyl group is linked to R4 via a nitrogen atom N; and

[0427] Q2 represents selecting the bridge from the group consisting of the following items: C 1-6 alkylene moiety, C 6-10 The aryl group may contain one or two C atoms. 1-3 alkylene unit and a C 6-10 The aryl unit portion, wherein the bridge is optionally independently selected by C 1-24 Alkyl and OH groups are substituted once or multiple times;

[0428] N(CY2-R1)3(VI)

[0429] in:

[0430] Each -R1 is independently selected from: -CY2N(C1-C 24 Alkyl)2;-CY2NR7, wherein R7 and the nitrogen atom N to which it is attached represent optionally being bonded by one or more C atoms. 1-6 Alkyl-substituted heterocyclic alkyl groups, wherein the heterocyclic alkyl group is connected to the remainder of R1 via a nitrogen atom N; or optionally, a C1-C6 alkyl-substituted heteroaryl group, wherein the heteroaryl group is selected from: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-1-yl, pyrazol-3-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, 1,2,4-triazol-1-yl, 1,2,4-triazol-3-yl, and thiazolyl-2-yl; and

[0431] Each Y is independently selected from H, CH3, C2H5, and C3H7;

[0432] R1R2N-X-NR1R2(VII); and R1R2N-X-NR2(-Q2-R2N)n -X-NR1R2 (VII-B);

[0433] in:

[0434] -X- is selected from -CY2CY2-, cis- or trans-1,2-cyclohexylene, -CY2CY2CY2-, -CY2C(OH)YCY2-, wherein each Y is independently selected from H, CH3, C2H5 and C3H7;

[0435] n is an integer from 0 to 10;

[0436] Each R1 group is independently an alkyl, heterocyclic alkyl, heteroaryl, aryl, arylalkyl, or heteroarylalkyl group, each of which may optionally be substituted with a substituent selected from the group consisting of: hydroxyl, alkoxy, phenoxy, phosphonate, carboxamide, formamide, carboxylic ester, sulfonate, amine, monoalkylamine, or dialkylamine and N. + (R3)3, wherein R3 is selected from hydrogen, alkyl, alkenyl, arylalkyl, arylalkenyl, hydroxyalkyl, aminoalkyl and alkyl ether;

[0437] Each R2 is independently –CZ2-R4, wherein each Z is independently selected from H, CH3, C2H5, C3H7; and each –R4 is independently selected from optionally substituted –N(C1-C) 24 Alkyl)2;-NR7, wherein each -NR7 independently represents R7 and the nitrogen atom to which it is attached. N represents optionally being bound by one or more C atoms. 1-6 The portion of an alkyl-substituted heterocyclic alkyl group, wherein the heterocyclic alkyl group is linked to CZ2 via a nitrogen atom N; and optionally a C1-C6 alkyl-substituted heteroaryl group, wherein the heteroaryl group is selected from the group consisting of: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-1-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, and thiazolyl; and CH2N(R10)(R11).

[0438] Where N(R10)(R11) is selected from the group consisting of the following items: two (C 1-44 alkyl)amino; di(C) 6-10 Aryl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; di(C) 6-10 Aryl C 1-6Alkyl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; NR7, wherein R7 and the nitrogen atom N to which it is attached represent optional substitution by one or more C atoms. 1-20 Alkyl-substituted heterocyclic alkyl groups, wherein the heterocyclic alkyl group is connected to the remainder of R1 via a nitrogen atom N; bis(heterocyclic C 1-6 Alkyl)amino, wherein each of the heterocyclic alkyl groups is independently optionally constituting one or more C 1-20 Alkyl substitution; and di(heteroaryl C) 1-6 Alkyl)amino, wherein each of the heteroaryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; and

[0439] Q2 is the bridge selected from the group consisting of the following items: C 1-6 Alkylene bridges, C 6-10 Aleurone bridges may contain one or two Cs 1-3 alkylene unit and a C 6-10 The bridge of the aryl unit, wherein the bridge can be optionally and independently selected C 1-24 Alkyl and OH groups are substituted once or multiple times;

[0440]

[0441] in:

[0442] Each Q group independently represents –CY2– or –CY2CY2–, where each Y is independently selected from hydrogen, C 1-24 Alkyl or C 6-10 Aryl;

[0443] Each D group independently represents a heteroaryl or a group of the formula –NR–, provided that at least one D group represents a heteroaryl;

[0444] Each D1 group is represented by the group with the formula –NR'–.

[0445] The two –R' groups in the two D1 groups together form the bridging region -Q2-;

[0446] Q2 is the bridge selected from the group consisting of the following items: C 1-6 alkylene moiety, C 6-10 The arylene moiety may contain one or two C1-C3 alkylene units and one C6-C4 alkylene unit. 10 In the aryl unit portion, the bridge can optionally be independently selected by C. 1-24 Alkyl and OH groups are substituted once or multiple times; and

[0447] Each R group independently represents H and C. 1-24 Alkyl, C6-10 Aryl or C 5-10 heteroaryl; and

[0448] R1-CY2-(NR3)-CY2-R2-CY2-(NR3)-CY2-R1(IX)

[0449] in:

[0450] Each Y is independently selected from H, CH3, C2H5, and C3H7;

[0451] Each R1 is independently selected from C5-C6 alkyl-substituted C5-C6 alkyl groups. 10 heteroaryl, of which C5-C 10 The heteroaryl group is selected from pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-1-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, and thiazolyl-2-yl;

[0452] R2 is selected from C5-C6 heteroaryl groups with optional C1-C6 alkyl substitution, wherein the C5-C6 heteroaryl group is selected from pyridine-2,6-diyl, pyrazin-2,6-diyl, pyrazole-3,5-diyl, pyrazole-1,3-diyl, pyrrole-2,5-diyl, imidazole-2,5-diyl, imidazole-1,4-diyl, pyrimidine-2,6-diyl, 1,2,4-triazole-3,5-diyl, 1,2,4-triazole-1,3-diyl, 1,2,4-triazole-2,4-diyl, 1,2,3-triazole-1,4-diyl, 1,2,3-triazole-2,5-diyl, and thiazole-2,5-diyl.

[0453] Each R3 is independently selected from C1-C6 alkyl-substituted C 1-24 Alkyl, C 6-10 Aryl, C 6-10 Aryl C1-C 24 Alkyl, C 5-10 heteroaryl, C 5-10 heteroaryl C1-C 24 alkyl.

[0454] Clause 16. The method according to any one of Clauses 1 to 14, wherein the complex comprises one or more manganese ions and a porphyrin or porphyrinazine ligand of formula (X) or (XI):

[0455]

[0456] in:

[0457] Each R 1 R 2 R 3 and R 4 It is a 5- to 10-membered N-heteroaryl group optionally selected from the group consisting of one or more of the following: C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group and C 1-24 Alkylphenyl, C 1-24 alkylnaphthalene, C 1-24 Alkoxy and phenoxy, each of which may optionally be selected from C 1-6 Alkyl, halogenated and C 1-6 One or more substitutions in the group consisting of haloalkyl groups;

[0458] Each R 1a R 2a R 3a and R 4a Choose independently the group consisting of the following items: C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group and C 1-24 Alkylphenyl, C 1-24 alkylnaphthalene, C 1-24 Alkoxy and phenoxy, each of which may optionally be selected from C 1-6 Alkyl, halogenated and C 1-6 One or more substitutions in the group consisting of haloalkyl groups; and

[0459] n is between 0 and 2;

[0460] ,

[0461] in:

[0462] A 1 A 2 A 3 A 4 B 1 B 2 B 3 B 4 C 1 C 2 C 3 C 4 D 1 D 2 D3 and D 4 Independently selected from N, CH, CR n N + -H and N + -R n The condition is that at most one of A1, B1, C1, and D1 is N, N + -H or N + -R n No more than one of A2, B2, C2, and D2 is N, N + -H or N + -R n No more than one of A3, B3, C3, and D3 is N, N + -H or N + -R n And at most one of A4, B4, C4, and D4 is N, N + -H or N + -R n And among them:

[0463] Each R n Selected independently from C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group and C 1-24 Alkylphenyl, C 1-24 alkylnaphthalene, C 1-24 Alkoxy and phenoxy, each of which may optionally be selected from C 1-6 Alkyl, halogenated and C 1-6 One or more substitutions in the group consisting of haloalkyl groups;

[0464] Each R 1 R 2 R 3 and R 4 It is a 5- to 10-membered N-heteroaryl group optionally selected from the group consisting of one or more of the following: C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group and C 1-24 Alkylphenyl, C 1-24 alkylnaphthalene, C 1-24 Alkoxy and phenoxy, each of which may optionally be selected from C 1-6 Alkyl, halogenated and C 1-6 One or more substitutions in the group consisting of haloalkyl groups;

[0465] Each R 1a R 2a R 3a and R 4a Choose independently the group consisting of the following items: C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group and C 1-24 Alkylphenyl, C 1-24 alkylnaphthalene, C 1-24 Alkoxy and phenoxy, each of which may optionally be selected from C 1-6 Alkyl, halogenated and C 1-6 One or more substitutions in the group consisting of haloalkyl groups; and

[0466] n is between 0 and 2.

[0467] Clause 17. The method according to Clause 15, wherein the chelating agent is selected from formulas (I), (II), (II-B), (III), (IV), (V), (VB), (VI) and (VII), such as (I), (II), (IV), (V), (VB), (VI) and (VII).

[0468] Clause 18. The method according to any one of Clauses 1 to 14, wherein the chelating agent is selected from the group consisting of: 2,4-di-(2-pyridinyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate, 2,4-di-(2-pyridinyl)-3-(pyridin-2-ylmethyl)-7-methyl-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate, 9,9-dihydroxy-3-methyl-2,4-di-(2-pyridinyl)-7-(1-(N,N-dimethylamine)-ethyl-2-yl)-3,7-diaza-bicyclo[3.3.1]nonane-1,5-dicarboxylate, 2,4 -Di-(2-pyridyl)-3,7-dimethyl-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylic acid dimethyl ester, N,N-bis(pyridin-2-yl-methyl-1,1-bis(pyridin-2-yl)-1-aminoethane, N-methyl-N-(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine, N-benzyl-N-(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine, N-methyl-N,N',N'-tris(pyridin-2-ylmethyl)ethylenediamine, N-butyl-N,N',N'-tris(pyridin-2-ylmethyl)-1,2-ethylenediamine, N-octyl-N,N',N'-tris(pyridin-2-ylmethyl)-1,2-ethylenediamine, N, N, N', N'-Tetra(pyridin-2-yl-methyl)ethylene-1,2-diamine, N, N, N', N'-Tetra(benzimidazol-2-ylmethyl)ethylene-1,2-diamine, Tris(pyridin-2-ylmethyl)amine, 1,4,7,10-Tetra(2-pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane, 1-Methyl-4,7-bis(pyridin-2-ylmethyl)-1,4,7-triazacyclononane, 1-Methyl-4,7-bis(quinoline-2-ylmethyl)-1,4,7-triazacyclononane, 1-Ethyl-4,7-bis(quinoline-2-ylmethyl)-1,4,7-triazacyclononane, 2,6-bis(pyridin-2-ylmethyl)-1,1,7,7- Tetra(pyridin-2-yl)-2,6-diazaheptane, 2,6-bis(pyridin-2-ylmethyl)-1,1,7,7-tetra(pyridin-2-yl)-2,6-diazaheptane (N,N'-bis(dipyridin-2-ylmethyl)-N,N'-bis(pyridin-2-ylmethyl)-1,3-diamino-propane), 1,4,7-trimethyl-1,4,7-triazacyclononane, 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane and 5,10,15,20-tetra(4-pyridinyl)-21H,23H-porphyrin tetra(methyl chloride).

[0469] Clause 19. The method according to any one of Clauses 1 to 14, wherein the chelating agent is selected from the group consisting of: 2,4-di-(2-pyridinyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylic acid dimethyl ester, N,N-bis(pyridin-2-yl-methyl-1,1-bis(pyridin-2-yl)-1-aminoethane, N-methyl-N,N' N'-tris(pyridin-2-ylmethyl)ethylenediamine, tris(pyridin-2-ylmethyl)amine, 1,4,7,10-tetra(2-pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane, 1-ethyl-4,7-bis(quinoline-2-ylmethyl)-1,4,7-triazacyclononane and 2,6-bis(pyridin-2-ylmethyl)-1,1,7,7-tetra(pyridin-2-yl)-2,6-diazaheptane.

[0470] Clause 20. The method according to any one of Clauses 1 to 14, wherein the chelating agent is selected from the group consisting of: 2,4-di-(2-pyridinyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diazabicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate, N,N-bis(pyridin-2-yl-methyl-1,1-bis(pyridin-2-yl)-1-aminoethane, N-methyl-N,N',N'-tris(pyridin-2-ylmethyl)ethylenediamine, tris(pyridin-2-ylmethyl)amine and 2,6-bis(pyridin-2-ylmethyl)-1,1,7,7-tetra(pyridin-2-yl)-2,6-diazaheptane.

[0471] Clause 21. The method according to any one of Clauses 1 to 14, wherein the chelating agent is dimethyl 2,4-di-(2-pyridinyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate.

[0472] Clause 22. A composition comprising:

[0473] (i) An aqueous medium comprising a bisulfate or oxalate buffer and having a pH of about 1 to about 3.5;

[0474] (ii) Chlorite; and

[0475] (iii) A complex comprising one or more iron ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one iron ion via at least three nitrogen atoms, provided that the one or more polydentate ligands are not porphyrin or porphyrinazine ligands; or

[0476] A complex comprising one or more manganese ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one manganese ion by at least three nitrogen atoms.

[0477] Clause 23. The composition according to Clause 22, wherein the pH is from about 1.5 to about 3.0.

[0478] Clause 24. The composition according to Clause 22 or Clause 23, wherein the aqueous medium is as defined in any one of Clauses 3 to 9.

[0479] Clause 25. The composition according to any one of Clauses 22 to 24, wherein the chlorite is selected from the group consisting of sodium chlorite, potassium chlorite, lithium chlorite, calcium chlorite, barium chlorite and magnesium chlorite.

[0480] Clause 26. The composition according to Clause 25, wherein the chlorite is sodium chlorite.

[0481] Clause 27. The composition according to any one of Clauses 22 to 27, wherein the complex is as defined in any one of Clauses 12 to 21.

[0482] Clause 28. A method of treating water or a matrix, the method comprising: contacting the water or the matrix with a composition defined in any one of Clauses 22 to 27.

[0483] Clause 29. The method according to Clause 28, wherein the matrix is ​​a cellulose matrix.

[0484] Clause 30. The method according to Clause 29, wherein the substrate is wood pulp.

[0485] Clause 31. A solid composition comprising:

[0486] (i) A solid acid comprising a hydrogen sulfate or an oxalate, and having a pKa of about 1 to about 3.5 in water at 25°C;

[0487] (ii) Chlorite; and

[0488] (iii) A complex comprising one or more iron ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one iron ion via at least three nitrogen atoms, provided that the one or more polydentate ligands are not porphyrin or porphyrinazine ligands; or

[0489] A complex comprising one or more manganese ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one manganese ion by at least three nitrogen atoms.

[0490] Clause 32. The solid composition according to Clause 31, wherein the pKa is from about 1.5 to about 3.0.

[0491] Clause 33. The solid composition according to Clause 31 or Clause 32, wherein the solid acid comprises a hydrogen sulfate buffer.

[0492] Clause 34. A solid composition according to any one of Clauses 31 to 33, wherein the solid composition comprises an acid selected from the group consisting of sodium bisulfate, potassium bisulfate, sulfuric acid, hydrochloric acid, oxalic acid, and hydrobromic acid.

[0493] Clause 35. The solid composition according to Clause 34, wherein the acid is selected from sodium bisulfate, potassium bisulfate, and hydrochloric acid.

[0494] Clause 36. The solid composition according to any one of Clauses 31 to 35, wherein the solid composition further comprises an alkali metal halide.

[0495] Clause 37. The solid composition according to Clause 36, wherein the alkali metal halide is sodium chloride.

[0496] Clause 38. The solid composition according to any one of Clauses 31 to 37, wherein the chlorite is selected from the group consisting of sodium chlorite, potassium chlorite, lithium chlorite, calcium chlorite, barium chlorite and magnesium chlorite.

[0497] Clause 39. The solid composition according to Clause 38, wherein the chlorite is sodium chlorite.

[0498] Clause 40. A solid composition according to any one of Clauses 31 to 39, wherein the complex is as defined in any one of Clauses 12 to 21.

[0499] Clause 41. A composition comprising: a chlorite, an acid comprising a bisulfate or oxalate and having a pKa of about 1 to about 3.5 in water at 25°C, and one or more polydentate ligands, said polydentate ligands being chelating agents capable of chelating at least one iron or manganese ion by at least three nitrogen atoms.

[0500] Clause 42. The composition according to Clause 41, wherein the pKa is from about 1.5 to about 3.0.

[0501] Clause 43. The composition according to Clause 41 or Clause 42, wherein the composition comprises a bisulfate buffer.

[0502] Clause 44. The composition according to any one of Clauses 41 to 43, wherein the composition comprises an acid selected from the group consisting of sodium bisulfate, potassium bisulfate, sulfuric acid, hydrochloric acid, oxalic acid, and hydrobromic acid.

[0503] Clause 45. The composition according to Clause 44, wherein the acid is selected from sodium bisulfate, potassium bisulfate, and hydrochloric acid.

[0504] Clause 46. The composition according to any one of Clauses 41 to 45 further comprises an alkali metal halide.

[0505] Clause 47. The composition according to Clause 46, wherein the alkali metal halide is sodium chloride.

[0506] Clause 48. The composition according to any one of Clauses 41 to 47, wherein the chlorite is selected from the group consisting of sodium chlorite, potassium chlorite, lithium chlorite, calcium chlorite, barium chlorite and magnesium chlorite.

[0507] Clause 49. The composition according to Clause 48, wherein the chlorite is sodium chlorite.

[0508] Clause 50. The composition according to any one of Clauses 41 to 49, wherein the polydentate ligand is as defined in any one of Clauses 15 to 21.

[0509] Clause 51. A kit comprising the following separate items:

[0510] (i) Chlorite;

[0511] (ii) an acid comprising a hydrogen sulfate or oxalate, and having a pKa of about 1 to about 3.5 in water at 25°C; and

[0512] (iii) One or more polydentate ligands, said polydentate ligands being chelating agents capable of chelating at least one iron or manganese ion by at least three nitrogen atoms.

[0513] Clause 52. The kit described in Clause 51, wherein the chlorite is as defined in Clause 48 or Clause 49.

[0514] Clause 53. The kit described in Clause 51 or Clause 52, wherein the pKa is about 1.5 to about 3.0.

[0515] Clause 54. The kit according to any one of Clauses 51 to 53, wherein the acid comprises a hydrogen sulfate buffer.

[0516] Clause 55. The kit according to any one of Clauses 51 to 54, wherein the composition comprises an acid selected from the group consisting of sodium bisulfate, potassium bisulfate, sulfuric acid, hydrochloric acid, oxalic acid, and hydrobromic acid.

[0517] Clause 56. The kit according to Clause 55, wherein the acid is selected from sodium bisulfate, potassium bisulfate, and hydrochloric acid.

[0518] Clause 57. The kit according to any one of Clauses 51 to 56, wherein the composition further comprises an alkali metal halide.

[0519] Clause 58. The kit described in Clause 57, wherein the alkali metal halide is sodium chloride.

[0520] Clause 59. The kit according to any one of Clauses 51 to 58, wherein the multidentate ligand is as defined in any one of Clauses 15 to 21.

[0521] Clause 60. The kit according to any one of Clauses 51 to 59 further comprises an iron salt or a manganese salt.

[0522] Clause 61. A kit comprising the following separate items:

[0523] (i) Chlorite;

[0524] (ii) an acid comprising a hydrogen sulfate or oxalate and having a pKa of about 1 to about 3.5 in water at 25°C; and any one of (iii) or (iv) below:

[0525] (iii) A complex comprising one or more iron ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one iron ion via at least three nitrogen atoms, provided that the one or more polydentate ligands are not porphyrin or porphyrinazine ligands; or

[0526] (iv) A complex comprising one or more manganese ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one manganese ion by at least three nitrogen atoms.

[0527] Clause 62. The kit pursuant to Clause 61, wherein the chlorite is as defined in Clause 48 or Clause 49.

[0528] Clause 63. The kit described in Clause 61 or Clause 62, wherein the pKa is about 1.5 to about 3.0.

[0529] Clause 64. The kit according to any one of Clauses 61 to 63, wherein the acid comprises a bisulfate buffer.

[0530] Clause 65. The kit according to any one of Clauses 61 to 64, wherein the composition comprises an acid selected from the group consisting of sodium bisulfate, potassium bisulfate, sulfuric acid, hydrochloric acid, oxalic acid, and hydrobromic acid.

[0531] Clause 66. The kit according to Clause 65, wherein the acid is selected from sodium bisulfate, potassium bisulfate, and hydrochloric acid.

[0532] Clause 67. The kit according to any one of Clauses 61 to 66, wherein the composition further comprises an alkali metal halide.

[0533] Clause 68. The kit described in Clause 67, wherein the alkali metal halide is sodium chloride.

[0534] Clause 69. A kit according to any one of Clauses 61 to 68, wherein the complex is as defined in any one of Clauses 12 to 21.

[0535] The following non-limiting examples are used to further illustrate the invention.

[0536] experiment

[0537] Compound (1): [Fe(N2py3o-C1)Cl]Cl (N2py3o-C1 = 2,4-di-(2-pyridyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylic acid dimethyl ester) was obtained as described in WO 02 / 48301 (Unilever).

[0538] Compound (2): [Fe(MeN4py)Cl]Cl (MeN4py = N,N-bis(pyridin-2-yl-methyl-1,1-bis(pyridin-2-yl)-1-aminoethane), and MeN4py is prepared as described in EP0909809 (Unilever).

[0539] Compound (3): [Fe(Me-trispicen)Cl]Cl (Me-trispicen = N-methyl-N,N',N'-tris(pyridin-2-ylmethyl)ethylenediamine) was prepared as disclosed by Bernal et al. (J. Chem. Soc., Dalton Trans, 22, 3667-3675 (1995)).

[0540] Compound (4): [Fe2(μ-O)(μ-CH3CO2)(TPA)2](ClO4)3 (TPA = tris(pyridin-2-ylmethyl)amine) was prepared as described by L. Que et al. (J. Am. Chem. Soc., 112, 1554-1562 (1990)).

[0541] Compound (5): [Fe(CyclenPy4)](ClO4)2 (CyclenPy4 = 1,4,7,10-tetra(2-pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane) was prepared as described by XH Bu and colleagues (Polyhedron, 19, 431-435 (2000) and 17, 289-293 (1998)).

[0542] Compound (6): [Fe(II)(EtQuin2TACN)Cl]ClO4 (EtQuin2TACN = 1-ethyl-4,7-bis(quinoline-2-ylmethyl)-1,4,7-triazacyclononane) was prepared as described elsewhere (WO2001 / 064826).

[0543] Compound (7): [Fe2(μ-O)(μ-CH3COO)L](ClO4)4 (L = 2,6-bis(pyridin-2-ylmethyl)-1,1,7,7-tetra(pyridin-2-yl)-2,6-diazaheptane (N,N'-bis(dipyridin-2-ylmethyl)-N,N'-bis(pyridin-2-ylmethyl)-1,3-diamino-propane) has been prepared as described elsewhere (EP1165738B1).

[0544] Compound (8): [Mn(Bcyclam)Cl2] (Bcyclam = 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane) was prepared as described in WO98 / 39098 and J. Am. Chem. Soc., 122, 2512-2522 (2000).

[0545] Compound (9): [Mn2(μ-O)2(μ-CH3COO)(Me4-DTNE)]Cl2(Me4-DTNE = 1,2-bis-(4,7-dimethyl-1,4,7-triazacyclononane-1-yl)-ethane) was obtained as disclosed in WO 2011 / 106906 (Unilever PLC et al.).

[0546] Compound (10): [Mn2(μ-O)(μ-CH3COO)2(Me3TACN)2](PF6)2 (Me3TACN = 1,4,7-trimethyl-1,4,7-triazacyclononane) was obtained as described by JH Koek et al. (J. Chem. Soc., Dalton Trans., 353-362 (1996)).

[0547] Compound (11): 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphyrin chloride Mn(III) tetratetra(methyl chloride) [C 44 H 36 [Cl5MnN8] was purchased from Merck (Sigma Aldrich).

[0548] In all cases, a 1 mM stock solution of each compound was prepared (except for compounds (7) and (10) which were dissolved in ethanol, which were prepared in water). Each stock solution was further diluted in water to a concentration of 0.1 mM. This solution was used to measure the activity of ClO2 formation by each of the compounds, tested in aqueous solution at a concentration range of 0.1 to 10 μM in the pH range (see details of the concentrations used in each case in the following experiments).

[0549] All other chemicals were obtained from conventional chemical suppliers.

[0550] Comparative test: NaClO2 / pH 5 acetate buffer / compound 1.

[0551] Comparative experiments were conducted using 10 μM compound 1 in an aqueous solution at pH 5 (using acetic acid buffer (50 mM) and sodium chlorite (10 mM)) at 25°C for 1 hour. The resulting ClO2 formation was measured using absorbance at 359 nm and 1250 M. -1 cm -1 The extinction coefficient (J. Am. Chem. Soc., 136, 3680-3686 (2014)) was used for tracking. After one hour, the absorbance at 359 nm was measured to be 1.4, indicating that 1.1 mM ClO2 had been formed. Further ClO2 formation was observed after a reaction time exceeding one hour, indicating that the ClO2 formation process was relatively slow under these conditions.

[0552] Similar experiments using 5 μM and 1 μM of compound 1 yielded chlorine dioxide concentrations of 0.7 mM and 0.2 mM, respectively. The blank (without catalyst) showed almost no chlorine dioxide formation.

[0553] These results indicate that chlorine dioxide formation does indeed occur catalytically in an acetate buffer at pH 5 (which has been identified as suitable for the production of chlorine dioxide from sodium chlorite using compound 1), with the rate of formation depending on the concentration of the catalyst.

[0554] Experiment 1: NaClO2 / pH 2 NaHSO4 buffer / compound 1.

[0555] First, a blank experiment was performed at 22°C using 10 mM NaClO2 and 11 mM NaHSO4 in water (at pH 2.32). Slow chlorine dioxide formation was observed (with an absorbance of 1.36 at 359 nm after 1 hour, which corresponds to 1.05 mM chlorine dioxide based on 1250 M). -1 cm -1 The extinction coefficient (J. Am. Chem. Soc., 136, 3680-3686 (2014)).

[0556] When 0.1 μM of compound 1 was added to the solution, the same experiment under the same conditions produced a significant acceleration in the formation of chlorine dioxide (1.36 mM chlorine dioxide was formed after 1 hour).

[0557] Increasing the concentration of compound 1 to 1 μM resulted in the formation of 2.2 mM ClO2 within the same time period (1 hour), yielding approximately 1.36 mM ClO2. It should be noted that this is the same amount of chlorine dioxide formed after 1 hour without a catalyst, indicating a strong accelerating effect of this catalyst on the formation of chlorine dioxide.

[0558] Increasing the concentration of compound 1 to 10 μM resulted in the formation of 2.7 mM ClO2 within 1 hour, a slight improvement compared to using 1 μM compound 1. Under these conditions, the same amount of chlorine dioxide (2.7 mM) was formed after 5 minutes of reaction as after 1 hour, again demonstrating the strong accelerating effect of this catalyst on the formation of chlorine dioxide.

[0559] Table 1 summarizes the results obtained at different catalyst concentrations. Steady accumulation of chlorine dioxide was obtained when using 0.1–1 μM of Compound 1. Increasing the concentration to 5 μM or 10 μM of Compound 1 after 1 hour of reaction time resulted in significantly higher concentrations of chlorine dioxide after 5 minutes, compared to a reference without a catalyst.

[0560] Table 1. ClO2 formation (mM) after reaction times (pH 2.32, T=22°C) using 10 mM NaClO2 and 11 mM NaHSO4 and different concentrations of compound 1 at 300 s, 780 s and 3600 s.

[0561]

[0562] Compared with the use of acetate buffer at pH 5, the amount of chlorine dioxide produced when using compound 1 at pH 2.32 (1.1 mM, 0.7 mM, and 0.2 mM ClO2 produced after 1 hour using 10 µM, 5 µM, and 0.1 µM of compound 1 in acetate buffer was compared with 2.75 mM, 2.62 mM, and 1.63 mM ClO2 produced after 1 hour using 10 µM, 5 µM, and 0.1 µM of compound 1 in NaHSO4 buffer) was compared with ClO2 produced after 1 hour using 10 µM, 5 µM, and 0.1 µM of compound 1 in NaHSO4 buffer.

[0563] Experiment 2: NaClO2 / Various NaHSO4 concentrations / Compound 1.

[0564] A similar experiment as described above regarding Experiment 1 was conducted, but the amount of NaHSO4 in the solution was reduced.

[0565] As shown in Table 2 below, reducing the concentration of sodium bisulfate leads to an increase in the pH of the solution (by adding less acid to compensate for the pH increase caused by the addition of sodium chlorite).

[0566] Without a catalyst, a significant reduction in ClO2 formation was observed when using 2.8 mM or 1.1 mM sodium bisulfate. The addition of 0.5 μM or 1 μM compound 1 resulted in a significant increase in the chlorine dioxide formation rate, even when the sodium bisulfate concentration was only 1 / 4 of that used in Experiment 1.

[0567] These results indicate that the amount of sodium bisulfate can be reduced by adding a small amount of catalyst without losing activity against chlorine dioxide formation. Additionally, it should be noted that the activity decreases when the pH of the mixture is increased to pH 5.77 (even in the presence of the catalyst).

[0568] Table 2. ClO2 formation (mM) after 1 hour reaction time (T=22°C) using 10 mM NaClO2 and various concentrations of NaHSO4 and Compound 1. The pH of the solution was measured immediately after mixing NaHSO4 and sodium chlorite in water.

[0569]

[0570] Experiment 3: NaHSO4 / Various NaClO2 concentrations / Compound 1.

[0571] A similar experiment as described above was performed by reducing the amount of NaClO2 in the solution. The amount of NaHSO4 used in this experiment was 5.5 mM (half the amount used in Experiment 1). The results are shown in Table 3.

[0572] Table 3. ClO2 formation (mM) after 1 hour of reaction time (T=22°C) using various concentrations of NaClO2, 5.5 mM NaHSO4 and various concentrations of Compound 1.

[0573]

[0574] It was observed that, in the absence of a catalyst, the amount of chlorine dioxide formed decreased when 1 / 4 sodium chlorite was used. However, in the presence of compound 1, significantly more chlorine dioxide was measured even using the lowest levels of sodium chlorite (independent of the initial chlorite concentration and catalyst concentration).

[0575] Experiment 4: NaHSO4 / HCl / NaClO2 / Compound 1.

[0576] A similar experiment as described above regarding Experiment 3 was performed using a solution (in which various amounts of HCl were added to achieve a lower pH). The pH values ​​obtained with and without 0.1 μM of Compound 1, and the ClO2 formation after 5 minutes, are given in Table 4 below.

[0577] Table 4. ClO2 formation (mM) after 300 seconds of reaction time (T=22°C) with and without Compound 1, using 10 mM NaClO2, 5.7 mM NaHSO4, and various concentrations of HCl.

[0578]

[0579] It should be noted that even after a reaction time of only 5 minutes, the benefit of adding 1 μM catalyst was clearly observed. In the presence of 1 μM, the addition of HCl solution provided some additional ClO2 formation.

[0580] Experiment 5: HCl – without buffer / NaClO2 / compound 1.

[0581] In the absence of NaHSO4 in the solution, a similar experiment as described above regarding Experiment 4 was performed using 10 mM NaClO2 and various amounts of HCl. The pH values ​​obtained with and without 1 μM of compound 1, and the ClO2 formation after 5 minutes, are given in Table 5 below.

[0582] Table 5. ClO2 formation (mM) after 300 seconds of reaction time (T=22°C) with and without Compound 1 using HCl of various concentrations in the presence of 10 mM NaClO2.

[0583]

[0584] In each case, the benefits of adding 1 μM bispidon catalyst were very evident. As expected, increasing the amount of acid led to a decrease in the pH of the mixture. A small amount of ClO2 was formed after 5 minutes (increased slightly as the pH decreased), but in the presence of the catalyst, significantly higher levels of ClO2 were formed within the same time period. It should be noted that significantly less ClO2 was formed in the presence of 5 or 10 mM HCl (in the presence of the catalyst) compared to Comparative Experiment 4 (with HCl in the presence of sodium bisulfate).

[0585] Experiment 6: NaClO2 / pH 2 NaHSO4 buffer / compound 2-11.

[0586] A series of Mn and Fe complexes (complexes 2-11) were tested in an aqueous solution containing 11 mM NaHSO4 buffer and 10 mM NaClO2 at pH 2.0 using either a 1 or 10 µM complex concentration. The concentration of ClO2 formed was analyzed after 300 and 780 seconds.

[0587] Table 6. ClO2 formation (mM) after reaction times of 300 s and 780 s (pH 2, T=25°C) using 10 mM NaClO2 and 11 mM NaHSO4.

[0588]

[0589] *When described as > 2.5 mM, it should be noted that the absorbance at 359 nm becomes higher than about 3.

[0590] The results in Table 6 show that, in bisulfate buffer at pH 2, all the exemplified compounds accelerated the formation of chlorine dioxide from chlorite. The extent of chlorine dioxide formation after reaction times ranging from 300 s to 780 s depended on the catalyst used. Compounds 2-7 (especially compounds 2-4 and 7) showed a significant accelerating effect on the rate of chlorine dioxide formation, even at low concentrations (1 μM).

[0591] Experiment 7: NaClO2 / oxalic acid / compound 1.

[0592] A blank experiment was performed at 25°C using 10 mM NaClO2 and 10 mM oxalic acid in water at pH 2.0. Slow formation of chlorine dioxide was observed (with an absorbance of 0.17 at 359 nm after 1 hour, equivalent to 0.14 mM chlorine dioxide, based on 1250 M). -1 cm -1 The extinction coefficient (J.Am.Chem.Soc., 136, 3680-3686 (2014)).

[0593] Adding 0.1 µM of compound 1 to the solution resulted in a significant acceleration in chlorine dioxide formation under the same conditions (absorbance of 1.4 at 359 nm, equivalent to 1.1 mM chlorine dioxide formed after 1 hour). Increasing the concentration of compound 1 to 1 µM yielded an absorbance of 2.7 at 359 nm, equivalent to 2.2 mM ClO2 formed over the same time period (1 hour).

[0594] Increasing the concentration of compound 1 to 10 µM yielded an absorbance of 2.4 at 359 nm, which is equivalent to 1.9 mM ClO2 over 1 hour.

[0595] Table 7 summarizes the results obtained at different catalyst concentrations. Steady accumulation of chlorine dioxide was obtained when using 0.1–1 µM of Compound 1. Increasing the concentration to 10 µM of Compound 1 after 1 hour of reaction time resulted in a significantly higher concentration of chlorine dioxide after 5 minutes, compared to a reference without a catalyst, or compared to using 0.1 µM or 1 µM of Compound 1. However, after 1 hour, the amount of chlorine dioxide was slightly lower when using 10 µM of Compound 1 compared to using 1 µM of Compound 1.

[0596] Table 7. ClO2 formation (mM) after reaction times (pH 2, T=25°C) of 300 s, 780 s and 3600 s using 10 mM NaClO2 and 10 mM oxalate buffer and different concentrations of Compound 1.

[0597]

[0598] Compared with the use of acetate buffer at pH 5, the amount of chlorine dioxide produced when using 0.1 µM and 10 µM of compound 1 at pH 2 was significantly greater (1.1 mM and 0.2 mM ClO2 produced after 1 hour using 10 µM and 0.1 µM of compound 1 in acetate buffer were compared with 1.9 mM and 1.1 mM produced after 1 hour using 10 µM and 0.1 µM of compound 1 in oxalate buffer).

[0599] Experiment 8: NaClO2 / NaHSO4 / NaCl / Compound 1.

[0600] All experiments described in this section were conducted in 0.5 cm cuvettes instead of the 1.0 cm cuvettes used in experiments 1-7 above.

[0601] A blank experiment was performed at 25 °C using 10 mM NaClO2, 11 mM NaHSO4, and 100 mM NaCl in water at pH 2.0. A significant amount of chlorine dioxide was observed to form (an absorbance of 0.95 at 359 nm after 1 hour, equivalent to 1.5 mM chlorine dioxide, based on 1250 M). -1 cm -1 The extinction coefficient (J.Am.Chem. Soc., 136, 3680-3686(2014)).

[0602] When 0.3 µM of compound 1 was added to the solution, the same experiment under the same conditions produced a significant acceleration in the formation of chlorine dioxide (the absorbance at 359 nm was 1.6 after 1 hour, which is equivalent to the formation of 2.5 mM of chlorine dioxide).

[0603] Increasing the concentration of compound 1 to 1 µM yielded an absorbance of 3.0 at 359 nm, which is equivalent to 4.8 mM ClO2 over the same time period (1 hour).

[0604] Table 8 shows a summary of the results obtained at different catalyst concentrations.

[0605] Table 8. ClO2 formation (mM) after reaction times (pH 2, T = 25°C) using 10 mM NaClO2, 100 mM NaCl, and 11 mM NaHSO4, and different concentrations of Compound 1, at reaction times of 300 s, 780 s, and 3600 s. The values ​​in parentheses given in the table below are the concentrations of chlorine dioxide obtained under the same conditions without the addition of NaCl. Experiments were conducted in 0.5 cm cuvettes. This does not affect the calculated ClO2 concentrations.

[0606]

[0607] Compared to the absence of NaCl, the amount of chlorine dioxide produced in the presence of 100 mM NaCl using 1 µM of compound 1 in a pH 2 NaHSO4 buffer was significantly greater than that produced after 1 hour using 1 µM of compound 1 in the presence of 100 mM NaCl in a pH 2 NaHSO4 buffer (the 4.8 mM ClO2 produced after 1 hour using 1 µM of compound 1 in the presence of 100 mM NaCl in a pH 2 NaHSO4 buffer is compared with the 2.6 mM ClO2 produced after 1 hour using 1 µM of compound 1 in the absence of NaCl in a pH 2 NaHSO4 buffer).

[0608] Experiment 9: NaClO2 / pH 2 NaHSO4 buffer / Compound 1 / NaCl

[0609] Perform a similar experiment as described in Experiment 2, but using a fixed amount of NaHSO4 and adding different amounts of NaCl.

[0610] The experiment was conducted at 25°C in a mixture of 11 mM NaHSO4 buffer, 10 mM NaClO2 (at pH 2.0), and 1 μM of Compound 1. The effect of adding NaCl was tested. The amount of NaCl varied between 0 and 1000 mM. The concentration of ClO2 formed was analyzed after 60 minutes. Starting with 10 mM chlorite, a maximum of 8 mM ClO2 could be formed.

[0611] Table 9. ClO2 formation (mM) after 60 min reaction time (pH 2, T = 25°C) using 0-1 μM compound 1, 10 mM NaClO2 and 11 mM NaHSO4.

[0612]

[0613] The results listed in Table 9 indicate that the presence of NaCl, along with compound 1, accelerates the formation of chlorine dioxide from chlorite. The amount of chlorine dioxide formed after a one-hour reaction time increases with increasing NaCl concentration, up to a concentration of 600 mM NaCl. For amounts greater than 600 mM NaCl, a stable plateau is reached in terms of ClO2 formation. It should be noted that when starting with 10 mM chlorite, a maximum concentration of 8 mM ClO2 can be formed.

[0614] In the absence of compound 1, the addition of NaCl has a very slight accelerating effect on the formation of chlorine dioxide from chlorite. However, this effect appears to plateau at a maximum of 100 mM NaCl, meaning that increasing the NaCl concentration beyond this value does not accelerate the formation of chlorine dioxide from chlorite. With the addition of NaCl, the ClO2 yield increased from 14% to 21%, an increase of 7%. This is significantly lower than the increase in ClO2 yield from 33% to 69% (i.e., an increase of 36% and more than double) with the addition of both compound 1 and NaCl.

[0615] In summary, the rate and extent of ClO2 formation were significantly higher in the presence of both compound 1 and NaCl (e.g., 100 mM or 200 mM NaCl) compared to the absence of NaCl or compound 1. The significant acceleration of ClO2 formation when NaCl and compound 1 were combined was a completely unexpected observation.

Claims

1. A method for producing chlorine dioxide from chlorite, the method comprising: In an aqueous medium, bring the following items into contact: (i) the chlorite; as well as (ii) A complex comprising one or more iron ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one iron ion by at least three nitrogen atoms, provided that the one or more polydentate ligands are not porphyrin or porphyrinazine ligands; or A complex comprising one or more manganese ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one manganese ion by at least three nitrogen atoms; The aqueous medium contains a bisulfate or oxalate buffer and has a pH of about 1 to about 3.

5.

2. The method of claim 1, wherein the pH is from about 1.5 to about 3.

0.

3. The method according to claim 1 or claim 2, wherein the aqueous medium further comprises an acid selected from hydrochloric acid and hydrobromic acid, such as hydrochloric acid.

4. The method according to any one of claims 1 to 3, wherein the aqueous medium comprises an alkali metal halide, such as sodium chloride, optionally at a concentration of about 10 mM to about 6 M or about 100 mM to about 1 M.

5. The method according to any of the preceding claims, wherein the complex is pre-formed, and / or the aqueous medium comprises about 0.03 to about 5 μM of the complex.

6. The method according to any one of the preceding claims, wherein the method relates to using a chlorite selected from the group consisting of sodium chlorite, potassium chlorite, lithium chlorite, calcium chlorite, barium chlorite and magnesium chlorite, such as sodium chlorite.

7. The method according to any of the preceding claims, wherein the complex comprises one or more iron ions.

8. The method according to any of the preceding claims, wherein the complex comprises a chelating agent capable of chelating at least one iron or manganese ion by at least three nitrogen atoms, said chelating agent having the formula (I), (IB), (II), (II-B), (III), (IV), (V), (VB), (VC), (VI), (VII), (VII-B), (VIII), (VIII-B), or (IX): in: Each D is independently selected from the group consisting of: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-1-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, and thiazolyl-2-yl, each of which may optionally be substituted by one or more groups independently selected from the group consisting of: -F, -Cl, -Br, -OH, -OC1-C4 alkyl, -NH-CO-H, -NH-CO-C1-C4 alkyl, -NH2, -NH-C1-C4 alkyl, and -C1-C4 alkyl; Each or every R1 and R2 is independently selected from the group consisting of the following items: C1-C 24 Alkyl, C 6-10 Aryl C1-C6 alkyl, C 6-10 Aryl and C5-C 10 Heteroaryl C1-C6 alkyl groups, each of which may optionally be substituted with one or more groups selected from the group consisting of: -F, -Cl, -Br, -OH, -OC1-C4 alkyl, -NH-CO-H, -NH-CO-C1-C4 alkyl, -NH2, -NH-C1-C4 alkyl, and –SC1-C4 alkyl; and CH2CH2N(R10)(R11), Where N(R10)(R11) is selected from the group consisting of the following items: two (C 1-44 alkyl)amino; di(C) 6-10 Aryl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; di(C) 6-10 Aryl C 1-6 Alkyl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; NR7, wherein R7 and the nitrogen atom N to which it is attached represent optional substitution by one or more C atoms. 1-20 Alkyl-substituted heterocyclic alkyl groups, wherein the heterocyclic alkyl group is connected to the remainder of R1 via a nitrogen atom N; bis(heterocyclic C 1-6 Alkyl)amino, wherein each of the heterocyclic alkyl groups is independently optionally constituting one or more C 1-20 Alkyl substitution; and di(heteroaryl C) 1-6 Alkyl)amino, wherein each of the heteroaryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; R3 and R4 are independently selected from hydrogen, C1-C8 alkyl, C1-C8 alkyl-O-C1-C8 alkyl, C6-C 10 Aryloxy C1-C8 alkyl, C6-C 10 Aryl, C1-C8 hydroxyalkyl, C6-C 10 Aryl C1-C6 alkyl and C5-C 10 Heteroaryl C1-C6 alkyl groups and -(CH2) 0-4 C(O)OR5, wherein R5 is independently selected from: hydrogen, C1-C8 alkyl, and C 6-10 Aryl; Q2 represents selecting the bridge from the group consisting of the following items: C 1-6 alkylene moiety, C 6-10 The aryl group may contain one or two C atoms. 1-3 alkylene unit and a C 6-10 The aryl unit portion, wherein the bridge is optionally independently selected by C 1-24 Alkyl and OH groups are substituted once or multiple times; and X is selected from C=O and -[C(R6)2] 0-3 - where each R6 is independently selected from hydrogen, hydroxyl, C1-C4 alkoxy and C1-C4 alkyl; in: Each Q is independently selected from -CR4R5CR6R7- and -CR4R5CR6R7CR8R9-; R4, R5, R6, R7, R8 and R9 are independently selected from: H, C1-C4 alkyl and hydroxy C1-C4 alkyl; Each of R1, R2, and R3 is independently selected from the group consisting of: hydrogen, C1-C 24 Alkyl group, CH2CH2OH, CH2COOH, CH2PO3H2, C5-C 10 Heteroaryl C1-C6 alkyl groups and CH2CH2N(R10)(R11), Where N(R10)(R11) is selected from the group consisting of the following items: two (C 1-44 alkyl)amino; di(C) 6-10 Aryl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; di(C) 6-10 Aryl C 1-6 Alkyl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; NR7, wherein R7 and the nitrogen atom N to which it is attached represent optional substitution by one or more C atoms. 1-20 Alkyl-substituted heterocyclic alkyl groups, wherein the heterocyclic alkyl group is connected to the remainder of R1 via a nitrogen atom N; bis(heterocyclic C 1-6 Alkyl)amino, wherein each of the heterocyclic alkyl groups is independently optionally constituting one or more C 1-20 Alkyl substitution; and di(heteroaryl C) 1-6 Alkyl)amino, wherein each of the heteroaryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; and Q2 is the bridge selected from the group consisting of the following items: C 1-6 alkylene moiety, C 6-10 The aryl group may contain one or two C atoms. 1-3 alkylene unit and a C 6-10 In the aryl unit portion, the bridge can optionally be independently selected by C. 1-24 Alkyl and OH groups are substituted once or multiple times; in: Each -Q- is independently selected from -N(R)C(R1)(R2)C(R3)(R4)- and -N(R)C(R1)(R2)C(R3)(R4)C(R5)(R6)-; Each -Q1- is independently selected from -N(R')C(R1)(R2)C(R3)(R4)- and -N(R')C(R1)(R2)C(R3)(R4)C(R5)(R6)-; Each R is independently hydrogen or selected from the group consisting of: C1-C 20 Alkyl, C2-C 20 alkenyl, C2-C 20 alkynyl group, C6-C 10 Aryl and C7-C 20 Arylalkyl groups, each of which may optionally be C1-C6 alkyl groups and / or C5-C6 alkyl groups. 10 Heteroaryl substitution; and CH2CH2N(R10)(R11), Where N(R10)(R11) is selected from the group consisting of the following items: two (C 1-44 alkyl)amino; di(C) 6-10 Aryl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; di(C) 6-10 Aryl C 1-6 Alkyl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; NR7, wherein R7 and the nitrogen atom N to which it is attached represent optional substitution by one or more C atoms. 1-20 Alkyl-substituted heterocyclic alkyl groups, wherein the heterocyclic alkyl group is connected to the remainder of R1 via a nitrogen atom N; bis(heterocyclic C 1-6 Alkyl)amino, wherein each of the heterocyclic alkyl groups is independently optionally constituting one or more C 1-20 Alkyl substitution; and di(heteroaryl C) 1-6 Alkyl)amino, wherein each of the heteroaryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; The two –R' groups in the two Q1 groups together form the bridging portion –Q2-; Q2 is the bridge selected from the group consisting of the following items: C 2-6 alkylene moiety, C 6-10 The arylene moiety may contain one or two C1-C3 alkylene units and one C6-C4 alkylene unit. 10 In the aryl unit portion, the bridge can optionally be independently selected by C. 1-24 Alkyl substitution once or multiple times; and R1-R6 are each independently selected from: H, C 1-4 Alkyl and hydroxy C 1-4 alkyl; in: Each -R1 is independently selected from -CH2N(C1-C 24 The heteroaryl group is selected from: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, 1,2,4-triazol-1-yl, 1,2,4-triazol-3-yl, and thiazolyl-2-yl; Each -R2 independently represents -R4-R5; Each -R3 and each -R6 independently represents hydrogen, or a group selected from the following: C1-C6 alkyl, C6 ... 10 Aryl, C5-C 10 heteroaryl, C6-C 10 Aryl C1-C6 alkyl and C5-C 10 Heteroaryl C1-C6 alkyl groups, each of which may optionally be C1-C6 alkyl substituted; Each -R4- independently represents a C1-C6 alkylene group that is optionally alkyl-substituted; Each -R5 independently represents -CH2N(C1-C 24 The heteroaryl group is selected from the group consisting of: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-1-yl, and thiazolyl-2-yl; Each -NR7 independently represents where R7 and the nitrogen atom N it is attached to are optionally represented by one or more C atoms. 1-20 The alkyl-substituted heterocyclic alkyl group, wherein the heterocyclic alkyl group is linked to R4 via a nitrogen atom N; and Q2 represents selecting the bridge from the group consisting of the following items: C 1-6 alkylene moiety, C 6-10 The aryl group may contain one or two C atoms. 1-3 alkylene unit and a C 6-10 The aryl unit portion, wherein the bridge is optionally independently selected by C 1-24 Alkyl and OH groups are substituted once or multiple times; N(CY2-R1)3(VI) in: Each -R1 is independently selected from: -CY2N(C1-C 24 Alkyl)2;-CY2NR7, wherein R7 and the nitrogen atom N to which it is attached represent optionally being bonded by one or more C atoms. 1-6 Alkyl-substituted heterocyclic alkyl groups, wherein the heterocyclic alkyl group is connected to the remainder of R1 via a nitrogen atom N; or optionally, a C1-C6 alkyl-substituted heteroaryl group, wherein the heteroaryl group is selected from: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-1-yl, pyrazol-3-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, 1,2,4-triazol-1-yl, 1,2,4-triazol-3-yl, and thiazolyl-2-yl; and Each Y is independently selected from H, CH3, C2H5, and C3H7; R1R2N-X-NR1R2 (VII); and R1R2N-X-NR2(-Q2-R2N) n -X-NR1R2 (VII-B); in: -X- is selected from -CY2CY2-, cis- or trans-1,2-cyclohexylene, -CY2CY2CY2-, -CY2C(OH)YCY2-, wherein each Y is independently selected from H, CH3, C2H5 and C3H7; n is an integer from 0 to 10; Each R1 group is independently an alkyl, heterocyclic alkyl, heteroaryl, aryl, arylalkyl, or heteroarylalkyl group, each of which may optionally be substituted with a substituent selected from the group consisting of: hydroxyl, alkoxy, phenoxy, phosphonate, carboxylic ester, formamide, carboxylic ester, sulfonate, amine, monoalkylamine, or dialkylamine and N. + (R3)3, wherein R3 is selected from hydrogen, alkyl, alkenyl, arylalkyl, arylalkenyl, hydroxyalkyl, aminoalkyl and alkyl ether; Each R2 is independently –CZ2-R4, wherein each Z is independently selected from H, CH3, C2H5, C3H7; and each –R4 is independently selected from optionally substituted –N(C1-C) 24 Alkyl)2;-NR7, wherein each -NR7 independently represents R7 and the nitrogen atom to which it is attached. N represents optionally being bound by one or more C atoms. 1-6 The portion of an alkyl-substituted heterocyclic alkyl group, wherein the heterocyclic alkyl group is linked to CZ2 via a nitrogen atom N; and optionally a C1-C6 alkyl-substituted heteroaryl group, wherein the heteroaryl group is selected from the group consisting of: pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-1-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, and thiazolyl; and CH2N(R10)(R11). Where N(R10)(R11) is selected from the group consisting of the following items: two (C 1-44 alkyl)amino; di(C) 6-10 Aryl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; di(C) 6-10 Aryl C 1-6 Alkyl)amino, wherein each of the aryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; NR7, wherein R7 and the nitrogen atom N to which it is attached represent optional substitution by one or more C atoms. 1-20 Alkyl-substituted heterocyclic alkyl groups, wherein the heterocyclic alkyl group is connected to the remainder of R1 via a nitrogen atom N; bis(heterocyclic C 1-6 Alkyl)amino, wherein each of the heterocyclic alkyl groups is independently optionally constituting one or more C 1-20 Alkyl substitution; and di(heteroaryl C) 1-6 Alkyl)amino, wherein each of the heteroaryl groups is independently optionally bounded by one or more C 1-20 Alkyl substitution; and Q2 is the bridge selected from the group consisting of the following items: C 1-6 Alkylene bridges, C 6-10 Aleurone bridges may contain one or two Cs 1-3 alkylene unit and a C 6-10 The bridge of the aryl unit, wherein the bridge can be optionally and independently selected C 1-24 Alkyl and OH groups are substituted once or multiple times; in: Each Q group independently represents –CY2– or –CY2CY2–, where each Y is independently selected from hydrogen, C 1-24 Alkyl or C 6-10 Aryl; Each D group independently represents a heteroaryl group or a group of the formula –NR–, provided that at least one D group represents a heteroaryl group; Each D1 group is represented by the group with the formula –NR'–. The two –R' groups in the two D1 groups together form the bridging region -Q2-; Q2 is the bridge selected from the group consisting of the following items: C 1-6 alkylene moiety, C 6-10 The arylene moiety may contain one or two C1-C3 alkylene units and one C6-C4 alkylene unit. 10 In the aryl unit portion, the bridge can optionally be independently selected by C. 1-24 Alkyl and OH groups are substituted once or multiple times; and Each R group independently represents H and C. 1-24 Alkyl, C 6-10 Aryl or C 5-10 heteroaryl; and R1-CY2-(NR3)-CY2-R2-CY2-(NR3)-CY2-R1(IX) in: Each Y is independently selected from H, CH3, C2H5, and C3H7; Each R1 is independently selected from C5-C6 alkyl-substituted C5-C6 alkyl groups. 10 Heteroaryl, wherein the C5-C 10 The heteroaryl group is selected from pyridin-2-yl, pyrazin-2-yl, quinoline-2-yl, pyrazol-3-yl, pyrazol-1-yl, pyrrole-2-yl, imidazole-2-yl, imidazole-4-yl, benzimidazole-2-yl, pyrimidin-2-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-1-yl, 1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, and thiazolyl-2-yl; R2 is selected from C5-C6 heteroaryl groups optionally substituted with C1-C6 alkyl groups, wherein the C5-C6 heteroaryl group is selected from pyridine-2,6-diyl, pyrazin-2,6-diyl, pyrazole-3,5-diyl, pyrazole-1,3-diyl, pyrrole-2,5-diyl, imidazole-2,5-diyl, imidazole-1,4-diyl, pyrimidine-2,6-diyl, 1,2,4-triazole-3,5-diyl, 1,2,4-triazole-1,3-diyl, 1,2,4-triazole-2,4-diyl, 1,2,3-triazole-1,4-diyl, 1,2,3-triazole-2,5-diyl, and thiazole-2,5-diyl. Each R3 is independently selected from C1-C6 alkyl-substituted C 1-24 Alkyl, C 6-10 Aryl, C 6-10 Aryl C1-C 24 Alkyl, C 5-10 heteroaryl, C 5-10 heteroaryl C1-C 24 alkyl.

9. The method according to any one of claims 1 to 6, wherein the complex comprises one or more manganese ions and a porphyrin or porphyrinazine ligand of formula (X) or (XI): in: Each R 1 R 2 R 3 and R 4 It is a 5- to 10-membered N-heteroaryl group optionally selected from the group consisting of one or more of the following: C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group and C 1-24 Alkylphenyl, C 1-24 alkylnaphthalene, C 1-24 Alkoxy and phenoxy, each of which may optionally be selected from C 1-6 Alkyl, halogenated and C 1-6 One or more substitutions in the group consisting of haloalkyl groups; Each R 1a R 2a R 3a and R 4a Choose independently the group consisting of the following items: C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group and C 1-24 Alkylphenyl, C 1-24 alkylnaphthalene, C 1-24 Alkoxy and phenoxy, each of which may optionally be selected from C 1-6 Alkyl, halogenated and C 1-6 One or more substitutions in the group consisting of haloalkyl groups; and n is between 0 and 2; ， in: A 1 A 2 A 3 A 4 B 1 B 2 B 3 B 4 C 1 C 2 C 3 C 4 D 1 D 2 D 3 and D 4 Independently selected from N, CH, CR n N + -H and N + -R n The condition is that at most one of A1, B1, C1, and D1 is N, N + -H or N + -R n No more than one of A2, B2, C2, and D2 is N, N + -H or N + -R n No more than one of A3, B3, C3, and D3 is N, N + -H or N + -R n And at most one of A4, B4, C4, and D4 is N, N + -H or N + -R n And among them: Each R n Selected independently from C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group and C 1-24 Alkylphenyl, C 1-24 alkylnaphthalene, C 1-24 Alkoxy and phenoxy, each of which may optionally be selected from C 1-6 Alkyl, halogenated and C 1-6 One or more substitutions in the group consisting of haloalkyl groups; Each R 1a R 2a R 3a and R 4a Choose independently the group consisting of the following items: C 1-24 Alkyl, C 3-8 cycloalkyl, C 4-8 Cycloalkenyl, C 1-24 alkenyl, phenyl, naphthyl, C 1-24 alkynyl group and C 1-24 Alkylphenyl, C 1-24 alkylnaphthalene, C 1-24 Alkoxy and phenoxy, each of which may optionally be selected from C 1-6 Alkyl, halogenated and C 1-6 One or more substitutions in the group consisting of haloalkyl groups; and n is between 0 and 2.

10. The method of claim 8, wherein the chelating agent is selected from: (i) Equations (I), (II), (II-B), (III), (IV), (V), (VB), (VI), and (VII), such as (I), (II), (IV), (V), (VB), (VI), and (VII); or (ii) The group consisting of the following: dimethyl 2,4-di-(2-pyridyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate, dimethyl 2,4-di-(2-pyridyl)-3-(pyridin-2-ylmethyl)-7-methyl-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylate, dimethyl 9,9-dihydroxy-3-methyl-2,4-di-(2-pyridyl)-7-(1-(N,N-dimethylamine)-ethyl-2-yl)-3,7-diaza-bicyclo[3.3.1]nonane-1,5-dicarboxylate, dimethyl 2,4-di-(2-pyridyl)-3, 7-Dimethyl-3,7-diaza-bicyclo[3.3.1]nonane-9-one-1,5-dicarboxylic acid dimethyl ester, N,N-bis(pyridin-2-yl-methyl-1,1-bis(pyridin-2-yl)-1-aminoethane, N-methyl-N-(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine, N-benzyl-N-(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine, N-methyl-N,N',N'-tris(pyridin-2-ylmethyl)ethylenediamine, N-butyl-N,N',N'-tris(pyridin-2-ylmethyl)-1,2-ethylenediamine, N-octyl-N,N',N'-tris(pyridin-2-ylmethyl)-1,2-ethylenediamine, N, N,N',N'-Tetra(pyridin-2-yl-methyl)ethylene-1,2-diamine, N,N,N', N'-Tetra(benzimidazol-2-ylmethyl)ethylene-1,2-diamine, tris(pyridin-2-ylmethyl)amine, 1,4,7,10-tetra(2-pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane, 1-methyl-4,7-bis(pyridin-2-ylmethyl)-1,4,7-triazacyclononane, 1-methyl-4,7-bis(quinoline-2-ylmethyl)-1,4,7-triazacyclononane, 1-ethyl-4,7-bis(quinoline-2-ylmethyl)-1,4,7-triazacyclononane, 2,6-bis(pyridin-2-ylmethyl)-1,1,7,7-tetra(pyridin-2-yl)-2,6-diazaheptane, 2,6- Bis(pyridin-2-ylmethyl)-1,1,7,7-tetra(pyridin-2-yl)-2,6-diazaheptane (N,N'-bis(dipyridin-2-ylmethyl)-N,N'-bis(pyridin-2-ylmethyl)-1,3-diamino-propane), 1,4,7-trimethyl-1,4,7-triazacyclononane, 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane and 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphyrin tetra(methyl chloride), such as 2,4-di-(2-pyridyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diazabicyclo[3.3].1] Nonane-9-one-1,5-dicarboxylic acid dimethyl ester.

11. A composition comprising: (i) An aqueous medium comprising a bisulfate or oxalate buffer and having a pH of about 1 to about 3.5; (ii) Chlorite; and (iii) A complex comprising one or more iron ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one iron ion via at least three nitrogen atoms, provided that the one or more polydentate ligands are not porphyrin or porphyrinazine ligands; or A complex comprising one or more manganese ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one manganese ion by at least three nitrogen atoms.

12. A method for treating water or a substrate, the method comprising: Contact the water or the matrix with the composition defined in claim 11, optionally wherein the matrix is ​​a cellulose matrix, such as wood pulp.

13. A solid composition comprising: (i) A solid acid comprising a hydrogen sulfate or an oxalate, and having a pKa of about 1 to about 3.5 in water at 25°C; (ii) Chlorite; and (iii) A complex comprising one or more iron ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one iron ion via at least three nitrogen atoms, provided that the one or more polydentate ligands are not porphyrin or porphyrinazine ligands; or A complex comprising one or more manganese ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one manganese ion by at least three nitrogen atoms.

14. A composition comprising: a chlorite, an acid comprising a bisulfate or oxalate and having a pKa of about 1 to about 3.5 in water at 25°C, and one or more polydentate ligands, said polydentate ligands being chelating agents capable of chelating at least one iron or manganese ion by at least three nitrogen atoms.

15. A kit comprising the following separate items: (i) Chlorite; (ii) an acid comprising a hydrogen sulfate or oxalate and having a pKa of about 1 to about 3.5 in water at 25°C; and any one of (iii) and (iv) below: (iii) One or more polydentate ligands, said polydentate ligands being chelating agents capable of chelating at least one iron or manganese ion via at least three nitrogen atoms, optionally further comprising an iron salt or a manganese salt; or (iv) A complex comprising one or more iron ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one iron ion by at least three nitrogen atoms, provided that the one or more polydentate ligands are not porphyrin or porphyrinazine ligands; or a complex comprising one or more manganese ions and one or more polydentate ligands, wherein the polydentate ligands are chelating agents capable of chelating at least one manganese ion by at least three nitrogen atoms.

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