Ion-selective membranes, ion-selective electrodes, ion sensors, sample testing devices, and coordination compounds

Abstract

This invention relates to ion-selective membranes, ion-selective electrodes, ion sensors, sample testing devices, and coordination compounds. A highly stable ion-selective membrane (ISM) containing a porphyrin thallium complex as an ion carrier is provided. The ISM contains: a compound represented by the following formula (1); a polymer; and a membrane solvent.

Description

Technical Field

[0001] This invention relates to ion-selective membranes, ion-selective electrodes, ion sensors, sample testing devices, and coordination compounds. Background Technology

[0002] Electrodes that selectively exhibit a potential response to specific ions are called ion-selective electrodes (ISEs). When an ISE is immersed in a solution, a potential difference corresponding to the activity of the target ion is generated at the interface between the ion-selective membrane and the solution, thereby causing a change in the electrode potential. Ion concentration measuring instruments (ion sensors) based on this phenomenon are widely used in physical and chemical industries, agriculture, medicine, food, and the environment. In medical sample testing devices, ion-selective electrodes are widely used to measure the concentrations of sodium, potassium, and chloride ions. For sodium and potassium ions, which are cations among these ions, ion-carrier type ISEs utilizing ion-selective membranes (ISMs) are widely used, in which the substance used to select the ion, called the ion carrier, is confined in a hydrophobic membrane. In contrast, for chloride ions, which are anions, there are no ion carriers as excellent as those for sodium and potassium ions, and in many cases, sparingly soluble salt type ISEs such as silver-silver chloride electrodes and ion-exchange type ISEs using ion-exchange resins, such as those with ammonium salts immobilized on them, are used.

[0003] Chloride ion carriers are broadly classified into three types: organometallic, organic, and metal complexes. Organometallic carriers exhibit high chloride ion selectivity, but in practice, due to the use of organomercury and organotin compounds, they are difficult to use from a chemical toxicity perspective. Furthermore, organic carriers such as dithiourea have low chloride ion selectivity. Metal complexes exhibit high chloride ion selectivity, but due to the use of indium and manganese, they are difficult to use from a chemical regulation perspective. In particular, specific measures are stipulated for indium compounds, such as the Ordinance on Prevention of Hazards Due to Specified Chemical Substances under the Industrial Safety and Health Law.

[0004] In *Analytical Science*, 1998, Vol. 14, pp. 79-84, porphyrin-thallium complexes as ion supports for chloride ions were disclosed. Thallium compounds are not limited by the specific measures described above, and from the viewpoint of chemical regulation, thallium compounds are preferred over indium complexes. The inventors have studied the properties of existing porphyrin-thallium complexes and recognized that they exhibit high chloride ion selectivity. Meanwhile, the inventors have found that ISMs containing existing porphyrin-thallium complexes are unstable, and the electromotive force responding to changes in ion concentration decreases over time; in this case, crystals of the porphyrin-thallium complex deposit on the surface of the ISM. In view of the above, the inventors believe that existing porphyrin-thallium complexes have problems with their affinity for ion-selective membrane matrices.

[0005] This invention was made to solve the above-mentioned problems, and the purpose of this invention is to provide a highly stable ISM containing a porphyrin thallium complex as an ion carrier. Summary of the Invention

[0006] An ISM containing a porphyrin thallium complex (Tl-Por) with appropriately substituents introduced therein as an ion support is provided.

[0007] That is, according to one embodiment of the present invention, an ion-selective membrane is provided, comprising: a compound represented by the following formula (1); a polymer; and a membrane solvent:

[0008]

[0009] In equation (1),

[0010] (i)R 151 To R 158 and R 101 To R 104 Each of the following can independently represent a hydrogen atom: a saturated or unsaturated alkyl group having one or more but less than 20 carbon atoms (substitutable); an alkoxy group having one or more but less than 20 carbon atoms (substitutable); an alkyl carbonyl group having one or more but less than 20 carbon atoms (substitutable); an aryl group having five or more but less than 20 carbon atoms (substitutable); an aryloxy group having five or more but less than 20 carbon atoms (substitutable); an aralkyl group having six or more but less than 30 carbon atoms (substitutable); or a halogen atom.

[0011] (ii) The substituents of the alkyl group in (i) are selected from the group consisting of: alkoxy groups having 1 or more but 4 or fewer carbon atoms; alkyl carbonyl groups having 1 or more but 4 or fewer carbon atoms; alkoxy carbonyl groups having 1 or more but 4 or fewer carbon atoms; alkyl carbonyl groups having 1 or more but 4 or fewer carbon atoms; aryl groups having 5 or more but 20 or fewer carbon atoms; cyano groups; and halogen atoms.

[0012] (iii) The substituents of each of the alkoxy, alkyl carbonyl, aryl, aryloxy, and aralkyl groups in (i) are selected from the group consisting of: saturated or unsaturated alkyl groups having 1 or more but less than 20 carbon atoms; alkoxy groups having 1 or more but less than 20 carbon atoms; alkyl carbonyl groups having 1 or more but less than 20 carbon atoms; alkoxy carbonyl groups having 1 or more but less than 20 carbon atoms; alkyl carbonyl groups having 1 or more but less than 20 carbon atoms; aryl groups having 5 or more but less than 20 carbon atoms; cyano groups; and halogen atoms.

[0013] (iv)R 151 To R 158 and R 101 To R 104 At least one of them represents a group other than a hydrogen atom, and

[0014] (v)X represents an anion.

[0015] Further features of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0016] Figure 1 This is a diagram used to illustrate an overview of ISE.

[0017] Figure 2 This is a diagram used to illustrate the overview of ISM.

[0018] Figure 3 This is a schematic diagram illustrating an overview of ion sensors using ISE.

[0019] Figure 4 This is a schematic diagram used to illustrate an overview of the sample testing apparatus.

[0020] Figure 5A This is a graph showing the results of Example 4, which demonstrates the electromotive force response when the NaCl concentration in the aqueous solution is changed. Figure 5B This is a graph showing the results of a comparative example used to display the electromotive force response when the concentration of NaCl in an aqueous solution is changed. Detailed Implementation

[0021] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following.

[0022] Figure 1 This is a schematic diagram illustrating an overview of the ISE 1000, including the ISM 1002 of this embodiment. Figure 1 In this design, the ISE 1000 includes an electrode 1001 comprising a conductor and an ISM 1002. The ISE 1000 may contain an internal liquid 1003. The ISE 1000 is configured in contact with the measurement solution 1020 together with a reference electrode 1010 serving as a comparison target. The reference electrode 1010 may contact the measurement solution via a salt bridge or a liquid junction. In the ISM 1002, which is in contact with the measurement solution 1020, a concentration (specifically, activity α) of the target ion 2005 in the measurement solution 1020 is generated. I The membrane potential (E) is logarithmically proportional to (aq) M The resulting membrane potential can be represented by the following Nernst equation.

[0023]

[0024] In the equation, E 0 Here, "z" represents the standard electrode potential, "R" represents the gas constant, "T" represents the absolute temperature, "z" represents the ion charge number, and "F" represents the Faraday constant. In the ion sensor, for solutions where the concentration of the target ion 2005 is known and for each of the measurement solutions, the concentration of the target ion 2005 in the measurement solution 1020 is calculated by measuring the potential difference between the ISM 1002 and the reference electrode 1010 using measuring instrument 1030. The following is a detailed description. Figure 1 The constituent elements shown.

[0025] Ion-selective electrode (ISE)

[0026] This embodiment provides an ion-selective electrode, comprising: an electrode including at least one conductor; and an ion-selective membrane of this embodiment.

[0027] Specifically, the ISE 1000 of this embodiment includes: an electrode 1001 comprising at least one conductor; and an ISM 1002. The ISE 1000 may have a known structure. As an example, as shown below... Figure 1The structure shown includes an internal electrode, represented by an electrode 1001 including a conductor, in contact with an internal liquid 1003, which in turn contacts an ISM 1002, and the ISM 1002 in contact with a measuring solution 1020. Besides the ISM 1002, known configurations can be used for the ISE 1000. Examples of the tubular body of the ISE 1000 include tubular bodies made of polymers such as polyvinyl chloride and polymethyl methacrylate. Examples of the internal liquid 1003 include aqueous solutions of sodium chloride and potassium chloride. Examples of the internal electrode include: metal / insoluble metal chlorides, such as silver-silver chloride; platinum; and conductive materials, such as conductive carbon materials and conductive polymers. Furthermore, a stationary type ISE 1000 in which the internal liquid 1003 is omitted and the ISM 1002 is formed on the electrode 1001 including the conductor is also preferred.

[0028] ISE 1000 can, for example, be used as follows Figure 1 The ISE 1000 is used as shown. Specifically, the ISE 1000 is configured to contact the measurement solution 1020 together with the reference electrode 1010. The reference electrode 1010 can contact the measurement solution 1020 via a salt bridge or a liquid junction. Known reference electrodes can be used as the reference electrode 1010. Specific examples include silver-silver chloride electrodes, conductive carbon materials, conductive polymers, and platinum.

[0029] Ion-selective membrane (ISM)

[0030] This embodiment provides an ion-selective membrane (ISM 1002) comprising: a compound represented by formula (1); a polymer; and a membrane solvent. (Refer to...) Figure 2An example of the ISM 1002 according to this embodiment is described. The ISM 1002 of this embodiment comprises an ion support 2001, a polymer 2002, and a membrane solvent 2003. Additionally, the ISM 1002 may contain an ionic additive 2004. The ion support 2001 is capable of generating an ion-selective membrane potential by selectively introducing the target ion 2005 from a measurement solution 1020 containing the target ion 2005 and foreign ions 2006 into the ISM 1002 (the process indicated by the arrow in the figure). Known methods can be used as a method for preparing the ISM 1002 of this embodiment. An example is described below. The ion support 2001, polymer 2002, membrane solvent 2003, and ionic additive 2004 are dissolved in a processing solvent, and the solution is cast onto a glass plate or the like and allowed to stand. After the processing solvent evaporates, the resulting material is shaped into a desired form. Preferably, a solvent capable of dissolving the components of the ISM 1002 to a concentration suitable for membrane formation is used as the processing solvent. Examples of ISM 1002 include tetrahydrofuran, chloroform, acetone, methyl ethyl ketone, toluene, and ethyl acetate. The thickness of ISM 1002 can be adjusted by controlling the amount of processing solvent, etc. Suitable thicknesses vary depending on the required mechanical strength and cost in the assumed application, but values ​​greater than 1 μm and less than 5 mm are given as examples. The components used to form ISM 1002 are described below.

[0031] Membrane solvent

[0032] The ISM of this embodiment comprises a membrane solvent. In many cases, the membrane solvent 2003 constitutes the largest mass proportion of the components used to form the ISM. The membrane solvent 2003, together with the polymer 2002, forms a flexible matrix and retains other constituent components, such as ion supports, within the matrix, thereby allowing the ISM to function. The measuring solution is typically an aqueous solution, therefore the membrane solvent 2003 of the ISM is hydrophobic, which allows the membrane solvent 2003 to retain the constituent components of the ISM so that the constituent components do not dissolve into the membrane. Simultaneously, the membrane solvent 2003 preferably has polarity such that it can satisfactorily retain the ion supports 2001 and ionic additives 2004, each possessing a certain degree of polarity, and introduce the target ion 2005 into the membrane. Known substances can be used as membrane solvent 2003. Examples include phthalates, fatty acid esters, o-nitrobenzene ethers, and phosphate esters. Furthermore, specific examples are selected from at least one of dioctyl phthalate, dioctyl adipate, dioctyl sebacate, o-nitrophenyl octyl ether (NPOE), o-nitrophenyl phenyl ether, 2-fluoro-2′-nitrophenyl ether, and trioctyl phosphate. Among these, NPOE, dioctyl phthalate, and 2-fluoro-2′-nitrophenyl ether are preferred. The composition ratio of the membrane solvent 2003 in the ISM can be appropriately selected according to the application of the ion-sensitive membrane. As an example, a composition ratio of 10% to 90% of the ISM mass can be given.

[0033] polymer

[0034] The ISM of this embodiment comprises a polymer. In many cases, polymer 2002 has the second largest mass ratio in the components used to form the ISM, second only to membrane solvent 2003. Polymer 2002, together with membrane solvent 2003, forms a matrix and serves to maintain the shape of the ISM as a solid membrane. For contact with the measuring solution, which is an aqueous solution, to form the ISM and to form a matrix together with the hydrophobic membrane solvent 2003, a polymer with low water solubility is preferably used as polymer 2002. Specific examples of the polymer may be at least one selected from polymers of ethylene that may have substituents (e.g., halogenated ethylene polymers or vinyl acetate polymers), polymers of styrene that may have substituents, polymers of acrylates, polymers of methacrylates, polymers of diene compounds, polyurethanes, polymers having siloxane bonds, and cellulose derivatives. Further specific examples may be at least one selected from polyvinyl chloride, polystyrene, polymethyl acrylate, polymethyl methacrylate, polyvinyl acetate, polybutadiene, polyisoprene, polyacrylonitrile, and cellulose acetate.

[0035] Ion carrier

[0036] The ion support in this embodiment is a compound capable of generating an ion-selective membrane potential by selectively introducing the target ion 2005 from the measurement solution into the ISM. The ion support 2001 in this embodiment is an ion support having a porphyrin-thallium complex structure represented by formula (1). Three types of ion supports for chloride ions are known: organometallic, organic, and metal-complex types. Organometallic types are toxic, and organic types have low ion selectivity. Therefore, these types present problems in practical use. Porphyrin indium complexes, known as metal-complex types, are known to be toxic, and although less toxic than organometallic types, they are therefore subject to regulation. The inventors have changed the central metal of existing porphyrin indium complexes to thallium. That is, by using a porphyrin complex in which thallium, one of the major elements of Group 13, is used as the central metal, the inventors have made this porphyrin complex less toxic and less regulated compared to porphyrin indium complexes.

[0037] In their initial research, the inventors evaluated the properties of porphyrin-thallium complexes and recognized that they exhibited high chloride ion selectivity. However, they also found that ISMs containing porphyrin-thallium complexes had the following problems: the ISMs were unstable, and the electromotive force (EMF) responding to changes in ion concentration decreased over time; in this case, porphyrin-thallium complex crystals deposited on the surface of the ISM. In view of the above, the inventors believed that porphyrin-thallium complexes had problems with their affinity for ion-selective membrane matrices. Porphyrin-thallium complexes are π-conjugated planar molecules and therefore can readily form intermolecular associations. That is, the inventors believed that when using existing porphyrin-thallium complexes, the complexes formed associations. Therefore, the inventors conceived the following: Such associations have low solubility in the membrane solvent, thus the porphyrin-thallium complexes deposited from the ISM over time, resulting in a decrease in the effective ion carrier concentration and a decrease in EMF over time. Therefore, in order to solve the above problems, the inventors have carried out molecular design of ion supports with high affinity for the matrix formed by membrane solvent and polymer. Specifically, the inventors have carried out molecular design from the following two perspectives, and have verified them. That is, the two perspectives are (1) improving affinity for the matrix by introducing substituents and (2) suppressing association caused by steric hindrance by introducing substituents.

[0038] Viewpoint (1) involves a method of introducing relatively flexible functional groups into the π-conjugated expanded porphyrin ring, thereby improving affinity for membrane solvents and polymers as relatively flexible molecules. Viewpoint (2) involves a molecular design that increases the volume of Tl-Por in the direction perpendicular to the porphyrin ring by introducing steric hindrance of substituents, thereby increasing the distance between Tl-Por molecules and inhibiting the formation of associative bonds between Tl-Por molecules. This effect is envisioned to be manifested in the Tl-Por with introduced substituents as a whole. First, introducing substituents into unsubstituted Tl-Por introduces a steric hindrance effect, thereby increasing the distance between Tl-Por molecules, resulting in a reduction of intermolecular association. Second, regarding Tl-Por with the introduction of a phenyl group at the meta position of the porphyrin, the plane of the introduced phenyl group has a steric hindrance effect because even when the group is unsubstituted, the plane is maintained to some extent relative to the plane of the porphyrin ring, thus making this Tl-Por more advantageous than the unsubstituted Tl-Por. Introducing substituents into the introduced phenyl group is effective because it allows the plane of the phenyl group to be further maintained relative to the plane of the porphyrin ring. From this perspective, it is effective to introduce substituents into the ortho and meta positions of the porphyrin bonded to the meta-phenyl group relative to the introduced porphyrin. When the formation of associative molecules between Tl-Por molecules is suppressed and the affinity of Tl-Por to the matrix is ​​improved, Tl-Por can be stably maintained in the ISM. With this configuration, the effective ion carrier concentration can be suppressed over time. Furthermore, as a result, the change in electromotive force caused by ion selection over time can be suppressed. In addition, when the affinity of Tl-Por to the matrix can be improved, the effective concentration of Tl-Por that can be stably maintained in the ISM can be improved. The foregoing leads to an improvement in the ion selection electromotive force, which is a characteristic of the ion carrier. Specifically, the electromotive force relative to the target ion can be improved to improve the sensitivity of the ion sensor.

[0039] Specifically, in embodiments of the present invention, the ion-selective membrane may comprise an ion carrier represented by formula (1):

[0040]

[0041] In equation (1),

[0042] (i)R 151 To R 158 and R 101 To R 104Each of the following can independently represent a hydrogen atom, a saturated or unsaturated alkyl group having one or more but less than 20 carbon atoms (substitutable), an alkoxy group having one or more but less than 20 carbon atoms (substitutable), an alkyl carbonyl group having one or more but less than 20 carbon atoms (substitutable), an aryl group having five or more but less than 20 carbon atoms (substitutable), an aryloxy group having five or more but less than 20 carbon atoms (substitutable), an aralkyl group having six or more but less than 30 carbon atoms (substitutable), or a halogen atom.

[0043] (ii) The substituents of the alkyl group in (i) are selected from the group consisting of: alkoxy groups having 1 or more but 4 or fewer carbon atoms; alkyl carbonyl groups having 1 or more but 4 or fewer carbon atoms; alkoxy carbonyl groups having 1 or more but 4 or fewer carbon atoms; alkyl carbonyl groups having 1 or more but 4 or fewer carbon atoms; aryl groups having 5 or more but 20 or fewer carbon atoms; cyano groups; and halogen atoms.

[0044] (iii) and (i) are respectively selected from the group consisting of: saturated or unsaturated alkyl groups having 1 or more but less than 20 carbon atoms; alkoxy groups having 1 or more but less than 20 carbon atoms; alkyl carbonyl groups having 1 or more but less than 20 carbon atoms; alkoxy carbonyl groups having 1 or more but less than 20 carbon atoms; alkyl carbonyl groups having 1 or more but less than 20 carbon atoms; aryl groups having 5 or more but less than 20 carbon atoms; cyano groups; and halogen atoms.

[0045] (iv)R 151 To R 158 and R 101 To R 104 At least one of them represents a group other than a hydrogen atom, and

[0046] (v)X represents an anion.

[0047] Furthermore, in this embodiment, the ion-selective membrane may comprise an ion carrier represented by formula (2):

[0048]

[0049] In equation (2),

[0050] (i)R 12 To R 16 R 22 To R 26 R 32 To R 36 and R 42 To R 46Each of the following can independently represent a hydrogen atom: a saturated or unsaturated alkyl group having one or more but less than 20 carbon atoms (substitutable); an alkoxy group having one or more but less than 20 carbon atoms (substitutable); an alkyl carbonyl group having one or more but less than 20 carbon atoms (substitutable); an aryl group having five or more but less than 20 carbon atoms (substitutable); an aryloxy group having five or more but less than 20 carbon atoms (substitutable); or an aralkyl group, hydroxyl group, or halogen atom having six or more but less than 30 carbon atoms (substitutable).

[0051] The alkyl substituent in (ii)(i) is any one of the following: an alkoxy group having one or more but four or fewer carbon atoms, an alkyl carbonyl group having one or more but four or fewer carbon atoms, an alkoxy carbonyl group having one or more but four or fewer carbon atoms, an alkyl carbonyloxy group having one or more but four or fewer carbon atoms, an aryl group having five or more but twenty or fewer carbon atoms, a cyano group, or a halogen atom.

[0052] In (iii) and (i), the substituents of alkoxy, alkyl carbonyl, aryl, aryloxy, and aralkyl are each of the following: a saturated or unsaturated alkyl group having one or more but four or fewer carbon atoms; an alkoxy group having one or more but four or fewer carbon atoms; an alkyl carbonyl group having one or more but four or fewer carbon atoms; an alkoxy carbonyl group having one or more but four or fewer carbon atoms; an alkyl carbonyloxy group having one or more but four or fewer carbon atoms; an aryl group having five or more but twenty or fewer carbon atoms; a cyano group; or a halogen atom.

[0053] (iv)R 12 To R 16 R 22 To R 26 R 32 To R 36 and R 42 To R 46 At least one of them represents a group other than a hydrogen atom, and

[0054] (v)X represents an anion.

[0055] In equation (2), R is more preferred. 12 To R 16 R 22 To R 26 R 32 To R 36 and R 42 To R 46Each of the following can independently represent a hydrogen atom: a saturated or unsaturated alkyl group having one or more but less than four carbon atoms, a substituent alkoxy group having one or more but less than four carbon atoms, a substituent alkyl carbonyl group having one or more but less than four carbon atoms, a substituent aryl group having five or more but less than ten carbon atoms, a substituent aryloxy group having five or more but less than ten carbon atoms, or a substituent aralkyl group, hydroxyl group, or halogen atom having six or more but less than ten carbon atoms.

[0056] Even better R 12 To R 16 R 22 To R 26 R 32 To R 36 and R 42 To R 46 Each of the following can independently represent a hydrogen atom: a saturated or unsaturated alkyl group having one or more but less than four carbon atoms, and an alkoxy group having one or more but less than four carbon atoms, which may have substituents. R is particularly preferred. 14 R 24 R 34 and R 44 Each represents a saturated or unsaturated alkyl group having one or more but no more than four carbon atoms, R 14 R 24 R 34 and R 44 Each represents an alkoxy group having one or more but no more than four carbon atoms, R 13 R 15 R 23 R 25 R 33 R 35 R 43 and R 45 Each represents a saturated or unsaturated alkyl group having one or more but no more than four carbon atoms, or R 13 R 15 R 23 R 25 R 33 R 35 R 43 and R 45 Each represents an alkoxy group having one or more but no more than four carbon atoms.

[0057] R 14 R 24 R 34 and R 44 Each represents an alkoxy group having one or more but fewer than four carbon atoms, or R 13R 15 R 23 R 25 R 33 R 35 R 43 and R 45 The preferred configuration is one in which each alkoxy group has one or more but no more than four carbon atoms.

[0058] Furthermore, in this embodiment, the ion-selective membrane may comprise an ion carrier represented by formula (3):

[0059]

[0060] In equation (3),

[0061] (i)R 51 To R 58 Each of the following can independently represent a hydrogen atom, a saturated or unsaturated alkyl group having one or more but less than 20 carbon atoms (substitutable), an alkoxy group having one or more but less than 20 carbon atoms (substitutable), an alkyl carbonyl group having one or more but less than 20 carbon atoms (substitutable), an aryl group having five or more but less than 20 carbon atoms (substitutable), an aryloxy group having five or more but less than 20 carbon atoms (substitutable), an aralkyl group having six or more but less than 30 carbon atoms (substitutable), or a halogen atom.

[0062] The alkyl substituent in (ii)(i) is any one of the following: an alkoxy group having one or more but four or fewer carbon atoms, an alkyl carbonyl group having one or more but four or fewer carbon atoms, an alkoxy carbonyl group having one or more but four or fewer carbon atoms, an alkyl carbonyloxy group having one or more but four or fewer carbon atoms, an aryl group having five or more but twenty or fewer carbon atoms, a cyano group, or a halogen atom.

[0063] In (iii) and (i), the substituents of alkoxy, alkyl carbonyl, aryl, aryloxy, and aralkyl are each of the following: a saturated or unsaturated alkyl group having one or more but four or fewer carbon atoms; an alkoxy group having one or more but four or fewer carbon atoms; an alkyl carbonyl group having one or more but four or fewer carbon atoms; an alkoxy carbonyl group having one or more but four or fewer carbon atoms; an alkyl carbonyloxy group having one or more but four or fewer carbon atoms; an aryl group having five or more but twenty or fewer carbon atoms; a cyano group; or a halogen atom.

[0064] (iv)R 51 To R 58 At least one of them represents a group other than a hydrogen atom, and

[0065] (v)X represents an anion.

[0066] In equation (3), R is more preferred. 51 To R 58 Each of the following groups independently represents a hydrogen atom and may contain a saturated or unsaturated alkyl group having one or more but less than four carbon atoms, a substituted alkoxy group having one or more but less than four carbon atoms, a substituted alkyl carbonyl group having one or more but less than four carbon atoms, a substituted aryl group having five or more but less than ten carbon atoms, a substituted aryloxy group having five or more but less than ten carbon atoms, or a substituted aralkyl group or halogen atom having six or more but less than ten carbon atoms. R is particularly preferred. 51 To R 58 Each of the substituents independently represents a hydrogen atom, or a saturated or unsaturated alkyl group having one or more but less than four carbon atoms that may have substituents, and a particularly preferred example of a substituent is an alkoxycarbonyl group having one or more but less than four carbon atoms.

[0067] Furthermore, in equation (3), R is more preferred. 51 To R 58 Each ion support has groups other than hydrogen atoms. This ion support has a further increased volume in the direction perpendicular to the porphyrin ring plane and can more effectively suppress the formation of ion support aggregates.

[0068] Furthermore, in this embodiment, the ion-selective membrane may comprise an ion carrier represented by formula (4):

[0069]

[0070] In equation (4),

[0071] (i)R 412 To R 416 R 422 To R 426 R 432 To R 436 and R 442 To R 446 Each of the following can independently represent a hydrogen atom, a saturated or unsaturated alkyl group having one or more but less than 20 carbon atoms (substitutable), an alkoxy group having one or more but less than 20 carbon atoms (substitutable), an alkyl carbonyl group having one or more but less than 20 carbon atoms (substitutable), an aryl group having five or more but less than 20 carbon atoms (substitutable), an aryloxy group having five or more but less than 20 carbon atoms (substitutable), an aralkyl group having six or more but less than 30 carbon atoms (substitutable), a hydroxyl group, or a halogen atom.

[0072] The alkyl substituent in (ii)(i) is any one of the following: an alkoxy group having one or more but four or fewer carbon atoms, an alkyl carbonyl group having one or more but four or fewer carbon atoms, an alkoxy carbonyl group having one or more but four or fewer carbon atoms, an alkyl carbonyloxy group having one or more but four or fewer carbon atoms, an aryl group having five or more but twenty or fewer carbon atoms, a cyano group, or a halogen atom.

[0073] In (iii) and (i), the substituents of alkoxy, alkyl carbonyl, aryl, aryloxy, and aralkyl are each of the following: a saturated or unsaturated alkyl group having one or more but four or fewer carbon atoms; an alkoxy group having one or more but four or fewer carbon atoms; an alkyl carbonyl group having one or more but four or fewer carbon atoms; an alkoxy carbonyl group having one or more but four or fewer carbon atoms; an alkyl carbonyloxy group having one or more but four or fewer carbon atoms; an aryl group having five or more but twenty or fewer carbon atoms; a cyano group; or a halogen atom.

[0074] (iv)R 412 To R 416 R 422 To R 426 R 432 To R 436 and R 442 To R 446 At least one of them represents a group other than a hydrogen atom.

[0075] (v)X represents an anion, and

[0076] (vi)R 413 R 415 R 423 R 425 R 433 R 435 R 443 Or R 445 At least one of them represents an alkoxy group having one or more but less than 20 carbon atoms that may have substituents.

[0077] In this ion support, the -O- group of the alkoxy group is hydrophilic and flexible. Therefore, when this ion support is introduced into an ISM, its degradation over time can be further reduced.

[0078] In equation (4), R is more preferred. 412 To R 416 R 422 To R 426 R 432 To R 436 and R 442 To R 446Each of the following can independently represent a hydrogen atom, a saturated or unsaturated alkyl group having one or more but less than four carbon atoms that may have substituents, an alkoxy group having one or more but less than four carbon atoms that may have substituents, an alkyl carbonyl group having one or more but less than four carbon atoms that may have substituents, an aryl group having five or more but less than ten carbon atoms that may have substituents, an aryloxy group having five or more but less than ten carbon atoms that may have substituents, an aralkyl group having five or more but less than ten carbon atoms that may have substituents, a hydroxyl group, or a halogen atom.

[0079] Preferred R 413 R 415 R 423 R 425 R 433 R 435 R 443 and R 445 Each refers to an alkoxy group having one or more but less than 20 carbon atoms, which may have substituents. More preferably, R 413 R 415 R 423 R 425 R 433 R 435 R 443 and R 445 Each represents an alkoxy group that may have substituents and has one or more but no more than four carbon atoms.

[0080] In this ion support, the -O- group of the alkoxy group is hydrophilic and flexible. Therefore, when this ion support is introduced into ISM, its degradation over time can be further reduced. Furthermore, this ion support has eight alkoxy groups, thus increasing its volume in the direction perpendicular to the porphyrin ring plane compared to cases with fewer alkoxy groups, and more effectively suppressing the formation of ion support aggregates.

[0081] In addition, another embodiment provides a coordination compound represented by formula (4):

[0082]

[0083] In equation (4),

[0084] (i)R 412 To R 416 R 422 To R 426 R 432 To R 436 and R 442 To R 446Each of the following can independently represent a hydrogen atom, a saturated or unsaturated alkyl group having one or more but less than 20 carbon atoms (substitutable), an alkoxy group having one or more but less than 20 carbon atoms (substitutable), an alkyl carbonyl group having one or more but less than 20 carbon atoms (substitutable), an aryl group having five or more but less than 20 carbon atoms (substitutable), an aryloxy group having five or more but less than 20 carbon atoms (substitutable), an aralkyl group having six or more but less than 30 carbon atoms (substitutable), a hydroxyl group, or a halogen atom.

[0085] The alkyl substituent in (ii)(i) is any one of the following: an alkoxy group having one or more but four or fewer carbon atoms, an alkyl carbonyl group having one or more but four or fewer carbon atoms, an alkoxy carbonyl group having one or more but four or fewer carbon atoms, an alkyl carbonyloxy group having one or more but four or fewer carbon atoms, an aryl group having five or more but twenty or fewer carbon atoms, a cyano group, or a halogen atom.

[0086] In (iii) and (i), the substituents of alkoxy, alkyl carbonyl, aryl, aryloxy, and aralkyl are each of the following: a saturated or unsaturated alkyl group having one or more but four or fewer carbon atoms; an alkoxy group having one or more but four or fewer carbon atoms; an alkyl carbonyl group having one or more but four or fewer carbon atoms; an alkoxy carbonyl group having one or more but four or fewer carbon atoms; an alkyl carbonyloxy group having one or more but four or fewer carbon atoms; an aryl group having five or more but twenty or fewer carbon atoms; a cyano group; or a halogen atom.

[0087] (iv)R 412 To R 416 R 422 To R 426 R 432 To R 436 and R 442 To R 446 At least one of them represents a group other than a hydrogen atom.

[0088] (v)X represents an anion, and

[0089] (vi)R 413 R 415 R 423 R 425 R 433 R 435 R 443 Or R 445 At least one of them represents an alkoxy group having one or more but less than 20 carbon atoms that may have substituents.

[0090] In equation (4), R is more preferred. 412 To R 416R 422 To R 426 R 432 To R 436 and R 442 To R 446 Each of the following can independently represent a hydrogen atom: a saturated or unsaturated alkyl group having one or more but less than four carbon atoms, a substituent alkoxy group having one or more but less than four carbon atoms, a substituent alkyl carbonyl group having one or more but less than four carbon atoms, a substituent aryl group having five or more but less than ten carbon atoms, an aryloxy group having five or more but less than ten carbon atoms, or a substituent aralkyl group, hydroxyl group, or halogen atom having five or more but less than ten carbon atoms.

[0091] Preferred R 413 R 415 R 423 R 425 R 433 R 435 R 443 and R 445 Each refers to an alkoxy group having one or more but less than 20 carbon atoms, which may have substituents. More preferably, R 413 R 415 R 423 R 425 R 433 R 435 R 443 and R 445 Each represents an alkoxy group that may have substituents and has one or more but no more than four carbon atoms.

[0092] In addition, another embodiment provides a coordination compound represented by formula (5):

[0093]

[0094] In equation (5),

[0095] R 61 To R 68 Each can independently represent a saturated or unsaturated alkyl group having one or more but less than 20 carbon atoms, which may have substituents.

[0096] The substituent is selected from the group consisting of: alkoxy groups having 1 or more but 4 or fewer carbon atoms; alkyl carbonyl groups having 1 or more but 4 or fewer carbon atoms; alkoxy carbonyl groups having 1 or more but 4 or fewer carbon atoms; alkyl carbonyl groups having 1 or more but 4 or fewer carbon atoms; aryl groups having 5 or more but 20 or fewer carbon atoms; cyano groups; and halogen atoms, and

[0097] X represents an anion.

[0098] In equation (5), R is more preferred. 61 To R 68 Each of these terms independently represents a saturated alkyl group having one or more but fewer than four carbon atoms that may have substituents, and as a most preferred example, R can be given. 61 To R 68 Each represents a compound containing a methyl group.

[0099] Thallium, as the central metal of the ion carrier, has a trivalent valence and exhibits high chloride ion selectivity. To achieve this, the anion X in each of equations (1) to (5) is preferably a stable anion, which is preferably a halide ion or a group of atoms used to form a stable anion. By selecting a halide ion or a group of atoms used to form a stable anion, the valence of thallium is maintained at trivalent. Known anions can be used as anion X. Examples of anion X are any one of chloride ion, bromide ion, iodide ion, fluoride ion, trifluoroacetate ion, tetrafluoroborate ion, hexafluorophosphate ion, acetate ion, nitrate ion, perchlorate ion, or thiocyanate ion. In particular, chloride ion is most preferably used as anion X because chloride ion exhibits satisfactory chloride ion selectivity.

[0100] The specific structural formula of Tl-Por, which serves as an ion support according to this embodiment, is described below. However, the ion support according to this embodiment is not limited thereto.

[0101]

[0102]

[0103]

[0104]

[0105]

[0106] Depending on the application of the ion-selective membrane, the amount of Tl-Por introduced into the ISM of this embodiment can be appropriately selected. The Tl-Por content can be set to 0.1% by mass or more and 20% by mass or less of the ISM. Preferably, the content can be set to 0.5% by mass or more and 10% by mass or less. When the amount of Tl-Por introduced into the ISM is less than 0.1% by mass, the electromotive force response of the ISM to the target ion may decrease. Simultaneously, when the amount of Tl-Por introduced into the ISM is greater than 20% by mass, Tl-Por will deposit, thereby inhibiting the introduction of the target ion into the membrane.

[0107] The ISM of this embodiment exhibits high selectivity for halide ions, particularly chloride ions, by using Tl-Por. Specifically, the ISM exhibits high selectivity for bicarbonate ions, phosphate ions, and nitrate ions, which are interfering ions present in biological fluids such as blood and urine. Therefore, by using the ISM of this embodiment, an ISE with high selectivity for halide ions, represented by chloride ions, can be formed.

[0108] Ionic additives

[0109] The ISM of this embodiment may include ionic additives. Ionic additives are said to prevent ions that interfere with the detection of the target ion from entering the membrane. Ionic additives containing both hydrophilic cations and hydrophobic anions are preferably used in the Tl-Por of this embodiment. Known anions can be used as hydrophobic anions. As a method for identifying hydrophobicity, a method is provided for identifying whether the countercation is insoluble in water when the tetrabutylammonium ion is used as a countercation. Examples of hydrophobic anions may include anions of the following compounds: namely, anions of tetraphenylborate compounds, long-chain alkyl sulfonic acid compounds, long-chain dialkyl sulfosuccinic acid compounds, long-chain alkyl phosphoric acid compounds, long-chain dialkyl phosphoric acid compounds, and long-chain dialkylphosphorsuccinic acid compounds. Specific examples include the following anions: tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (TFPB), tetrakis(4-chlorophenyl)borate, tetrakis(4-fluorophenyl)borate, tetraphenylborate, decylsulfonic acid, dodecylsulfonic acid, dodecylbenzenesulfonic acid, octadecylsulfonic acid, oleylsulfonic acid, dimethylhexylsulfosuccinic acid, dioctylsulfosuccinic acid, didecylsulfosuccinic acid, di-dodecylsulfosuccinic acid, decylphosphonic acid, dodecylphosphonic acid, dodecylbenzenephosphonic acid, octadecylphosphonic acid, oleylphosphonic acid, dimethylhexylphosphonic acid, dioctylphosphonic acid, didecylphosphonic acid, di-dodecylphosphonic acid, dimethylhexylphosphosuccinic acid, dioctylphosphosuccinic acid, didecylphosphosuccinic acid, and di-dodecylphosphosuccinic acid.

[0110] Hydrophilic cations are used as cations in ionic additives. As a method for identifying hydrophilicity, a method is provided to determine whether a counter cation is soluble in water when used as a counter cation. Known cations that can be used as cations in ionic additives include alkali metal ions, alkaline earth metal ions, and ammonium ions. Specific examples include sodium ions, potassium ions, and ammonium ions.

[0111] Depending on the application of the ion-selective membrane, the content of the ionic additive in the ISM of this embodiment can be appropriately selected. For example, the content of the ionic additive falls within the range of 1 mol% to 100 mol% relative to Tl-Por. When the amount of ionic additive added is less than 1 mol% relative to Tl-Por, the electromotive force response of the ISM to the target ion may become slower. Meanwhile, when the amount of ionic additive added is greater than 100 mol% relative to Tl-Por, the ISM exhibits more of a cation exchanger function compared to its electromotive force response to anions, thus enabling electromotive force response to cations. A more preferred concentration is, for example, where the amount of ionic additive added falls within the range of 10 mol% to 50 mol% relative to Tl-Por. In general anion-selective electrodes (e.g., dithiourea), a combination of hydrophobic cations and hydrophilic anions is often chosen as its ionic additive. Tl-Por uses a combination of hydrophilic cations and hydrophobic anions, possibly because its ion selectivity as an ion carrier is activated by the interaction between the hydrophobic anion and Tl-Por.

[0112] Ion sensor

[0113] This embodiment provides an ion sensor, which includes: an ion-selective electrode of this embodiment; a reference electrode; and a measuring instrument configured to measure the potential difference between the ion-selective electrode and the reference electrode.

[0114] An ion sensor is a sensor that measures the concentration of a target ion in a sample. Figure 3 This is a schematic diagram illustrating an overview of an ion sensor 3050 (ion concentration measuring device) using an ISE on which an ISM of this embodiment is formed. Figure 3 In this configuration, the ISE 1000, together with a reference electrode 1010 used as a comparison target, is in contact with the measurement solution 1020. The reference electrode 1010 can be in contact with the measurement solution via a salt bridge or a liquid junction. In the ISE 1002, which is in contact with the measurement solution, the concentration (specifically, activity a) of the target ion in the measurement solution is determined. I The membrane potential (E) is logarithmically proportional to (aq) M In an ion sensor (following the Nernst equation), the concentration of the target ion in the measurement solution is calculated by measuring the potential difference between the ISM 1002 and the reference electrode 1010 in a solution where the concentration of the target ion is known and in the measurement solution using a measuring instrument such as a voltmeter 1030. The aforementioned electrode is preferably used as the reference electrode 1010. A general measuring instrument can be used. For example, a voltmeter with a large input resistance or a potentiostat in potentiostat mode can be used. The input resistance is preferably 10 Ω. 9Ω or higher, more preferably 10 12 Ω and above.

[0115] Sample testing device

[0116] This embodiment provides a sample testing apparatus, which includes: an ion-selective electrode of this embodiment; and a sample supply mechanism configured to supply a sample to the ion-selective electrode.

[0117] Reference Figure 4 An example of the sample testing apparatus of this embodiment is described. The sample testing apparatus 4000 introduces a sample into the apparatus through a sample inlet 4001, and supplies the sample to the ISE 1000 and reference electrode 1010 in the ISE unit 4004 via a flow path 4003, powered by a pump 4002, etc. The electromotive force generated in the ISE 1000 is measured and recorded by a measurement unit 4005. The sample used for measurement is collected in a collection container 4006. In addition to the foregoing, the sample testing apparatus may include a unit for supplying and mixing solutions for diluting the sample or a unit for measuring any other test item. By using the ISE 1000 with Tl-Por as an ion carrier, the sample testing apparatus can analyze anions, represented by chloride ions, with high precision.

[0118] By using a substituent-containing Tl-Por as an ion support to improve its affinity for the matrix, the ISM of this embodiment can stably maintain Tl-Por within the ISM. As a result, changes in the effective ion support concentration over time can be suppressed, as can changes in the electromotive force (EMF) caused by ion selection over time. When the effective concentration of Tl-Por, which can be stably maintained in the ISM, increases, the EMF generated by ion selection of the ion support in the ISE can be improved. Consequently, an ISE with an improved EMF for the target ion can be realized, i.e., a highly sensitive ion sensor. Using the ion sensor and sample testing apparatus, each with a highly sensitive and stable ISE, the concentration of the target ion can be measured, and the sample can be tested with high precision.

[0119] Example

[0120] The present invention is described in more detail below through examples, but the invention is not limited to these examples.

[0121] (1) Synthesis of Tl-Por

[0122] As examples, referring to non-patent literature (Polyhedron 1986, Vol. 5, pp. 1157-1164), Tl-Por, represented by formulas P-1, P-4, P-7, P-9, P-21, P-22, and P-27, were synthesized by reactions represented by formula (A). In formula (A), the synthesis reaction of Tl-Por represented by formula P-9 is described as representative.

[0123]

[0124] A more specific synthetic method is described by using Tl-Por, represented by Formula P-9, as an example. Commercially available 5,10,15,20-tetrakis(3,5-dimethoxyphenyl)porphyrin and 2 equivalents of thallium(III) chloride were dissolved in acetic acid. Sodium acetate was added to the solution, and the mixture was refluxed for 6 hours at 100 W in a microwave irradiation apparatus. The precipitate was collected by filtration and dried. The dried collected product was dissolved in toluene and filtered. The solvent was distilled off from the filtrate. Thus, Tl-Por, represented by Formula P-9, was obtained. The synthesis of Tl-Por represented by Formula P-9... 1 The H-NMR measurement results are as follows.

[0125] 1 ¹H-NMR (deuterated acetone) δ (ppm): 9.24 (d, 8H), 7.56 (s, 4H), 7.40 (s, 4H), 7.02 (s, 4H), 4.00 (s, 24H)

[0126] The comparative example compound represented by formula R-1 was also synthesized using the above method.

[0127]

[0128] (2) Preparation of ISM

[0129] The preparation methods of the ISMs used in the respective Examples and Comparative Examples are described. The following materials were used: 2-nitrophenyl octyl ether (NPOE) as the membrane solvent, polyvinyl chloride (PVC) as the polymer, Tl-Por as the ion carrier, sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaTFPB) as the ionic additive, and THF as the treatment solvent. NPOE, PVC, Tl-Por, and NaTFPB were dissolved by heating in THF, and the resulting mixture was cast onto a glass plate, followed by evaporation of THF. The ISMs were thus prepared. The mass ratio in the membrane was set to NPOE / PVC / Tl-Por = 66 / 33 / 1. The concentration of the ionic additive relative to Tl-Por was set to 5.6 mol% to 100 mol%. The thickness of the prepared ISM was approximately 0.4 mm.

[0130] (3) Production of ISE

[0131] The preparation methods of the ISE used in the respective examples and comparative examples are described. The ISM was cut to a suitable electrode size and welded to an electrode housing made of PVC under THF. The ISM was conditioned overnight with a 10 mM NaCl aqueous solution, and then placed between the Ag / AgCl electrode and the sample liquid via an internal liquid formed from the 10 mM NaCl aqueous solution, as shown. Figure 1 As shown.

[0132] (4) Evaluation

[0133] Evaluation of solubility

[0134] The absorbance of ISM is measured by varying the concentration of Tl-Por dissolved in NPOE. According to the Lambert-Beer law, the maximum concentration in the region where absorbance increases proportionally to concentration is defined as the saturation solubility.

[0135] Evaluation of ISM uniformity

[0136] The produced ISM was placed on a planar light source and photographed. Large aggregates were observed on the membrane surface and within the membrane.

[0137] Evaluation of electromotive force

[0138] like Figure 1 As shown, the ISE and Ag / AgCl, which serves as a reference electrode, are connected to an input resistor of 10 ohms, which is used as the measuring instrument. 12 A potentiostat with an Ω value was used to change the concentration of NaCl in the aqueous solution. The electromotive force (EMF) was measured. The measurement was performed at 23°C.

[0139] Stability evaluation

[0140] Before and after immersing ISM in a 10 mM NaCl aqueous solution and allowing it to stand for 4 days, the NaCl concentration-dependent EMF of ISM was measured, and its stability was evaluated by using the ratio of the slope of the EMF to the logarithm of the concentration (after standing / before standing).

[0141] (5) Results

[0142] Evaluation of solubility

[0143] Compared to Tl-Por represented by formula R-1, the Tl-Por represented by formulas P-1, P-4, P-7, P-9, P-21, P-22, and P-27, as Tl-Por with introduced substituents, exhibited a solubility in NPOE that was increased by 1.7 to more than 10 times. Among them, Tl-Por represented by formulas P-4 and P-9 showed a solubility of over 1% relative to NPOE. (The solubility of Tl-Por represented by formula R-1 is 0.09%).

[0144] Evaluation of ISM uniformity

[0145] In each of Examples 1 to 7, ISM was prepared using Tl-Por with introduced substituents represented by formulas P-1, P-4, P-7, P-9, P-21, P-22, and P-27, respectively. In the comparative example, ISM was prepared using Tl-Por represented by formula R-1.

[0146] No clear aggregation was identified in the backlit photographs of any of the ISMs in Examples 1 to 4. Aggregation was present in the ISMs prepared using Tl-Por represented by formulas P-21, P-22, and P-27 in Examples 5 to 7, but the aggregation was very small. Furthermore, no crystal deposition of Tl-Por was observed on the film surface in any of the ISMs in Examples 1 to 5. In contrast, large aggregations were identified in the ISMs of the comparative examples. Additionally, crystal deposition of Tl-Por represented by formula R-1 with a bluish-violet metallic luster was identified on the film surface.

[0147] Evaluation of electromotive force

[0148] Figure 5A and Figure 5B These are graphs showing the EMF response as the NaCl concentration in the aqueous solution changed when using the ISE in Example 4 and the Comparative Example, respectively. In each figure, the curve indicated by the black circle represents the response in the initial state, and the curve indicated by the white triangle represents the response after 4 days of storage in a 10 mM NaCl aqueous solution from the initial measurement. The horizontal axis of the graph represents the NaCl concentration (logarithmic), and the vertical axis represents the EMF. In each ISE, the EMF changes linearly with respect to the logarithm of the target ion concentration, and its slope represents the sensitivity to the target ion. Furthermore, in the case of the anion in this embodiment, the slope becomes a negative slope. Figure 5A The characteristics of ISE produced by setting the concentration of NaTFPB to 50% of the optimal concentration and using Tl-Por (Example 4) with introduced substituents represented by Formula P-9 are shown. The initial slope value obtained therefrom is -41.1 mV dec. -1(Change in EMF (in mV) when the concentration changes by an order of magnitude). Conversely, ISE prepared by setting the concentration of NaTFPB to 5.6% of the optimal concentration and using the comparative example's Tl-Por represented by formula R-1... Figure 5B The initial slope shown is -29.8mV Dec. -1 Table 1 shows a list of optimal concentrations of NaTFPB in ISE for Examples 1 to 7 and Comparative Examples, along with the slope values ​​at these optimal concentrations. The optimal concentration of NaTFPB was determined from the magnitude of the absolute value of the initial slope.

[0149] As can be seen from the table, in each of Examples 1 to 7 using Tl-Por with introduced substituents represented by formulas P-1, P-4, P-7, P-9, P-21, P-22, and P-27, the initial slope exhibits an initial slope of -37.2 mV dec. -1 to -46.2mV dec -1 The absolute value of this is greater than the absolute value in the comparison example.

[0150] Stability evaluation

[0151] The NaCl concentration-dependent EMF of each ISM was measured before and after immersion in a 10 mM NaCl aqueous solution and standing for 4 days. This was used to evaluate the stability of the ISE using Tl-Por. Figure 5A The ISE (Example 4) using Tl-Por as represented by Equation P-9 shown exhibits -42.4 mV dec -1 The slope, even after 4 days, remained almost unchanged from the initial slope. Conversely, in Figure 5B In the ISE of Tl-Por shown in the comparative example, as expressed by Equation R-1, the sensitivity decreased to -21.4 mV dec. -1 This is 0.72 times the initial sensitivity. Table 1 shows a list of the slopes and rates of change of slope (values ​​obtained by dividing the slope after 4 days by the initial slope) of ISE for Examples 1 to 7 and the Comparative Examples after 4 days of immersion. As can be seen from the table, in Examples 1 to 7, each using Tl-Por with introduced substituents represented by formulas P-1, P-4, P-7, P-9, P-21, P-22, and P-27, the rates of change of slope exhibit values ​​ranging from 0.92 to 1.04, which are greater than the rate of ISE (0.72) of Tl-Por represented by formula R-1 for the Comparative Examples.

[0152] Table 1: List of EMF responses of ISE when NaCl concentration in aqueous solution is changed.

[0153]

[0154] (5) Discussion

[0155] Solubility and uniformity evaluations revealed that introducing substituents into Tl-Por improved the solubility of each Tl-Por in the membrane solvent and its uniformity in the ISM matrix. This is likely because introducing relatively flexible functional groups into the π-conjugated expanded porphyrin ring improves the affinity of Tl-Por for relatively flexible molecular membrane solvents and polymers. Furthermore, this may be due to the steric hindrance inhibiting association through the introduction of substituents; the following two Tl-Pors exhibited particularly high solubility: the Tl-Por represented by Formula P-4 has three substituents at the ortho and para positions of the phenyl group in tetraphenylporphyrin; the Tl-Por represented by Formula P-9 has two substituents at the meta position. Consequently, the Tl-Por of the comparative example, represented by Formula R-1, which was difficult to stably exist in the membrane solvent and ISM matrix and aggregated in the membrane and deposited as crystals on the membrane surface, became able to stably remain in the membrane solvent and ISM matrix.

[0156] The electromotive force (EMF) evaluation revealed that the ISE of Tl-Por in Examples 1 to 7, using substituents, exhibited a greater absolute value than the slope of the slope of the ISE of Tl-Por represented by Formula R-1 in the Comparative Example. This is likely because the introduction of substituents into Tl-Por stabilizes it within the matrix, thereby increasing the amount of Tl-Por effectively acting as an ion carrier. Conversely, it is believed that the Tl-Por represented by Formula R-1 in the Comparative Example is difficult to stabilize in both the membrane solvent and the matrix, thus aggregating in the membrane and depositing as crystals on the membrane surface. Consequently, the amount of Tl-Por effectively acting as an ion carrier in the ISM is reduced, resulting in relatively low sensitivity.

[0157] Stability evaluation revealed that the ISE of the ISMs using the substituent-introduced Tl-Por in Examples 1 to 7 exhibited more stable sensitivity than that using the ISMs of the Comparative Examples. This is likely because the introduction of substituents into the Tl-Por stabilizes the number of Tl-Por molecules that effectively act as ion supports in the ISM, resulting in stable ISE properties. Conversely, in the case of the Tl-Por represented by Formula R-1 used in the Comparative Examples, it is conceivable that the number of Tl-Por molecules effectively acting as ion supports in the ISM gradually decreases, leading to a decline in ISE properties.

[0158] The following findings were observed from the above results.

[0159] Introducing substituents into Tl-Por improves its solubility in membrane solvents, uniformity in the ISM matrix, and stability.

[0160] The sensitivity of both the ISE and the ion sensor was improved by using an ISM with introduced substituents, Tl-Por.

[0161] The use of Tl-Por ISM with introduced substituents improved the time-dependent stability of the ion selection potential response of both the ISE and the ion sensor.

[0162] Specifically, according to this implementation scheme, it was verified that an ISM containing Tl-Por as an ion carrier with improved stability, an ISE and an ion sensor each with improved sensitivity, and an ISE and an ion sensor each with improved potential response stability can be provided. As a result, the value of devices using ISEs, such as ion sensors or sample testing devices, can be improved.

[0163] According to this implementation scheme, an ISM containing Tl-Por, which improves stability as an ion carrier, can be provided.

[0164] While the invention has been described with reference to exemplary embodiments, it will be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be accorded the broadest interpretation to cover all such variations and equivalent structures and functions.

Claims

1. An ion-selective membrane characterized in that, It includes: Compounds represented by the formula P-1, P-4, P-22 or P-27; polymer; and Membrane solvent: 。 2. The ion-selective membrane according to claim 1, wherein the polymer comprises at least one selected from polymers of ethylene that may have substituents, polymers of styrene that may have substituents, polymers of acrylates, polymers of methacrylates, polymers of diene compounds, polyurethanes, polymers having siloxane bonds, and cellulose derivatives.

3. The ion-selective membrane according to claim 1 or 2, wherein the polymer comprises at least one selected from polyvinyl chloride, polystyrene, polymethyl acrylate, polymethyl methacrylate, polyvinyl acetate, polybutadiene, polyisoprene, polyacrylonitrile, and cellulose acetate.

4. The ion-selective membrane according to claim 1 or 2, wherein the membrane solvent contains one of phthalate or o-nitrobenzene ether.

5. The ion-selective membrane according to claim 1 or 2, wherein the membrane solvent contains at least one selected from o-nitrophenyl octyl ether (NPOE), dioctyl phthalate, and 2-fluoro-2'-nitrophenyl ether.

6. The ion-selective membrane according to claim 1 or 2, further comprising an ionic additive.

7. The ion-selective membrane according to claim 6, wherein the ionic additive contains hydrophilic cations and hydrophobic anions.

8. An ion-selective electrode, characterized in that, It includes: Electrodes including at least one conductor; and The ion-selective membrane according to any one of claims 1 to 7.

9. An ion sensor, characterized in that, It includes: The ion-selective electrode according to claim 8; Reference electrode; and A measuring instrument configured to measure the potential difference between the ion-selective electrode and the reference electrode.

10. A sample testing device, characterized in that, It includes: The ion-selective electrode according to claim 8; and A sample supply mechanism configured to supply a sample to the ion-selective membrane.

11. An ion-selective membrane, characterized in that, It includes: Compounds represented by the following formula P-9; polymer; and Membrane solvent: 。

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