A pyrroloquinoline quinone ionic liquid, a preparation method and application thereof

Abstract

This invention discloses a pyrroloquinoline quinone ionic liquid, its preparation method, and its applications, belonging to the field of new materials technology. The ionic liquid is composed of the pyrroloquinoline quinone anion represented by Formula I and any one of the cations from Formulas II to V. It is prepared by mixing pyrroloquinoline quinone or its sodium salt with the corresponding cation in a solvent at a molar ratio of 1:1 to 1:3, reacting, separating, and drying. This ionic liquid combines the excellent properties of PQQ with those of ionic liquids, and when used in the preparation of high-purity nuclides in nuclear medicine, it can solve problems such as the easy loss of PQQ and the use of toxic raw materials in existing separation materials. When loaded onto supports such as silica gel for column chromatography separation, it exhibits high selectivity and good recovery rates in the separation of zirconium-yttrium, strontium-yttrium, etc., thanks to the metal coordination ability of PQQ. The preparation conditions are mild and the purification is simple, showing broad application prospects in the separation of key nuclides in nuclear medicine.

Description

Technical Field

[0001] This invention relates to the field of new material preparation technology, specifically to a pyrroloquinoline quinone ionic liquid, its preparation method, and its application. Background Technology

[0002] Ionic liquids are low-temperature or room-temperature molten salts composed of organic cations and various anions, possessing excellent physicochemical properties such as low volatility, good thermal stability, and a wide electrochemical window. In particular, ionic liquids exhibit satisfactory designability, and functionalized ionic liquids obtained through various combinations of cations and anions or specific functionalization reactions have been extensively studied and applied in catalysis, batteries, and separation. Polyionic liquids, in particular, are a class of polymeric compounds polymerized from ionic liquid monomers, combining the functional properties of ionic liquids with the structural stability of polymers. Related ionic network materials use polyionic chains as their framework, where balancing ions can participate in the completion or improvement of the network structure and introduce specific active sites for adsorption, catalysis, etc. The synergistic effect of polyionic chains and balancing ions endows the material with unique structure and function. Based on the structural correlation and functional synergy between the two, this type of material exhibits good designability and excellent comprehensive performance, showing broad prospects in multiple application fields. For example, it can be used for the selective separation of specific metal ions such as gold ions and uranyl ions (Chemical Engineering Journal 2024, 479, 147875; Chemical Engineering Journal 2025, 525, 170057); or as a functional component of flexible electronic devices, such as sensors (Small 2026, e12363; Separation and Purification Technology 2026, 394, 137384).

[0003] Pyrroloquinoline quinone (PQQ) is a redox coenzyme with a variety of unique physiological functions. It received GRAS (Generally Recognized As Safe) designation from the US Food and Drug Administration (FDA) in 2016, and my country approved pyrroloquinoline quinone disodium salt as a new food ingredient in 2023. First, the abundant carboxylic acid groups provide PQQ with the structural prerequisites for use as an anionic catalyst in the synthesis of ionic liquids. Second, PQQ can also be used as a catalyst in organic synthesis, such as catalyzing free radical cyclization (Angewandte Chemie International Edition 2025, 64, e202505431). In particular, PQQ has many potential chelation / complexation sites for stable binding with metal ions, making it an important metal adsorbent. For example, PQQ cofactor-bound Ln ions have been found in XoxF-type methanol dehydrogenase. 3+This is the first instance of rare earth elements playing a physiological role. However, when PQQ or its sodium salt is used alone for the adsorption of metal ions in aqueous systems, there is often a problem of loss.

[0004] In the field of medical radionuclide separation, zirconium-89 ( 89 Zr) and yttrium-90 ( 90 Y) are two very important medical radioactive metal nuclides, and obtaining high-purity nuclides through separation and purification is crucial for their practical use. Specifically, 89 Zr(t) 1 / 2 =78.4 h) is a novel positron-emitting isotope whose half-life matches well with the biological metabolic cycle of most antibodies, making it suitable for in vivo pharmacokinetic studies of antibodies or antibody-drug conjugates. Among its applications, it can be used for clear cell renal cell carcinoma imaging. 89 Zr-girentuximab has completed Phase III clinical trials. However, based on 89 Y(p,n) 89 Zr or 89 Y(d,2n) 89 Zr and other nuclear reactions produce 89 Zr often contains impurities that cannot be ignored (such as raw materials). 89 Y, etc.), and only drugs labeled with high-purity radionuclides can be used for effective diagnosis and treatment. Furthermore, due to... 89 Zr decay emits high-energy gamma rays, resulting in a high radiation dose, making it unsuitable for manual operation in large-scale production. Currently... 89 Zr is mainly separated automatically by column chromatography. The stationary phase packing used has considerable separation efficiency, but most of it is imported (such as from foreign companies such as Triskem and Eichrom Industries) and has a broad spectrum of applications. There is an urgent need for high-performance separation materials that combine efficiency and selectivity. 90 Y(t) 1 / 2 =64.2 h) is a pure β-decay nuclide, usually prepared by loading it onto carrier microspheres with a diameter of 20–60 micrometers. 90 Y-microsphere injection is widely used in the field of nuclear medicine. Its main components are... 90 Sr(t) 1 / 2 =28 a) is obtained by the β decay of the raw material, through 90 Sr- 90 This can be achieved using a Y generator. Alternatively, it can be implemented via... 90 Zr(n,p) 90 Y is prepared through neutron nuclear reactions, which involves the selective separation of Y from a mixed solution containing Zr and Y. Specifically, for 90 Sr- 90 Y-generator method for preparation 90 Y, due to 90Sr tends to deposit in bones, causing prolonged exposure to radiation, which is why it is used in medicine. 90 The purity of Y often needs to reach Y:Sr = 10. 6 The atomic ratio is 1:1. However, at the decay equilibrium of strontium-yttrium, the ratio Y:Sr = 1:4000, thus requiring highly selective separation materials. Patent CN 105478097A discloses a crown ether-based strontium-yttrium separation resin based on 18-crown-6, using it as the stationary phase and disodium ethylenediaminetetraacetate solution as the mobile phase. Column chromatography can yield yttrium with a purity of up to 95%. Patent CN 119524815A discloses a di(2-ethylhexyl)phosphate-functionalized silicon-based solid adsorbent that can specifically extract trivalent yttrium ions, thereby achieving efficient separation of yttrium and strontium. However, both the crown ether and the phosphate used have certain biological toxicity.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] Against this backdrop, leveraging the abundant carboxylic acid groups in PQQ, a series of PQQ ionic liquids can be prepared by transforming the cations. These materials combine the excellent designability of ionic liquids with the inherent properties of PQQ, showing broad application prospects in metal ion separation, catalysis, and biochemistry. In particular, in the field of metal ion separation, synthesizing a separation material suitable for aqueous systems with excellent selectivity, starting from natural bio-friendly substances (such as food ingredients), for the purification and preparation of high-purity medical radionuclides is especially important for subsequent clinical use.

[0007] The purpose of this invention is to provide a pyrroloquinoline quinone (PQQ) ionic liquid, its preparation method, and its applications. Specifically, it provides an application for the adsorption and separation of at least one metal ion among zirconium ions, yttrium ions, and strontium ions, effectively improving the problems of existing separation materials relying on imports and using toxic raw materials. It exhibits good selectivity for the target metal ions and achieves good separation results. Details are as follows:

[0008] This invention provides a pyrroloquinoline quinone ionic liquid, wherein the ionic liquid comprises anions and cations; Wherein, the anion is the pyrroloquinoline quinone anion represented by Formula I, where n = 1, 2 or 3; The cation is any one of formula II, formula III, formula IV or formula V: In Equation II, R1 is C1-C20 The hydrocarbon group, R2 is hydrogen, C1-C 20 Any one of the hydrocarbon groups or substituted hydrocarbon groups; In Equation III, R3 is C1-C 20 The hydrocarbon group, R4, R5, and R6 are hydrogen, C1-C 20 Any one of the hydrocarbon groups or substituted hydrocarbon groups; In formula IV, R7 is hydrogen, C1-C 20 Any one of the hydrocarbon groups or substituted hydrocarbon groups; In formula V, R8 represents hydrogen and C1-C. 20 Any one of the hydrocarbon groups or substituted hydrocarbon groups; The substituent of the substituted hydrocarbon group is at least one selected from hydroxyl, amino, carboxyl, ester, and sulfonic acid groups; In formulas IV and V, m1 and m2 refer to the number of repeating units, indicating that formulas IV and V are polymers.

[0009] Preferably, in the pyrroloquinoline quinone ionic liquid, the compound corresponding to the cation is a hydroxide or halide of formula II-V, wherein the halide is a fluoride, chloride, bromide or iodide.

[0010] The present invention also provides a method for preparing a pyrroloquinoline quinone ionic liquid, which involves mixing pyrroloquinoline quinone or its sodium salt with the corresponding cation in a solvent at a molar ratio of 1:1 to 1:3, reacting, separating, and drying to obtain the pyrroloquinoline quinone ionic liquid.

[0011] Preferably, in the above preparation method, the sodium salt of pyrroloquinoline quinone is a monosodium salt of pyrroloquinoline quinone, a disodium salt of pyrroloquinoline quinone, or a trisodium salt of pyrroloquinoline quinone; the solvent is selected from at least one of water, acetonitrile, methanol, ethanol, isopropanol, and acetone.

[0012] Preferably, in the above preparation method, the reaction temperature is from room temperature to 100°C, and the reaction time is 1 to 72 hours.

[0013] Preferably, in the above preparation method, the separation method is at least one of direct filtration, centrifugation, or filtration and centrifugation after adding solvent. When the product is a clear liquid, the clear liquid is dried. When the product is a solid, the precipitate or the filter cake obtained during filtration is washed and dried.

[0014] The pyrroloquinoline quinone ionic liquid provided by the present invention can be used for the adsorption and separation of metal ions. Preferably, the metal ions include at least one of zirconium ions, yttrium ions, and strontium ions. The pyrroloquinoline quinone ionic liquid is mixed with a support and then loaded into a separation column for column chromatography separation of metal ions.

[0015] More preferably, the carrier may be selected from at least one porous carrier material selected from silica gel, diatomaceous earth, zeolite, alumina, molecular sieve, and resin, and the eluent for column chromatography separation may be selected from at least one selected from oxalic acid, disodium ethylenediaminetetraacetate, diethylenetriaminepentaacetic acid, potassium chloride, calcium chloride, hydrochloric acid, and nitric acid solution.

[0016] The technical solution provided by this invention has the following advantages: This invention innovatively prepares a novel type of ionic liquid using pyrroloquinoline quinone (PQQ) as the anion. The PQQ ionic liquid provided by this invention has a unique structure, mild preparation conditions, simple purification process, and is easy to scale up for production, showing good prospects for industrial application.

[0017] The PQQ ionic liquid provided by this invention is derived from new food raw materials. When used as a separation material in the preparation of medical radionuclides, it can meet the specific biocompatibility requirements for subsequent clinical use.

[0018] The PQQ ionic liquid provided by this invention has shown excellent results in the separation of key nuclides in nuclear medicine, overcoming the problem of easy loss of PQQ or its sodium salt when adsorbing metal ions in an aqueous system. When used for zirconium-yttrium separation, the zirconium purity reaches 98%, and for strontium-yttrium separation, the yttrium purity reaches 95% with a recovery rate of 82%, meeting the stringent requirements for high-purity nuclide preparation and breaking the current reliance on imported separation materials.

[0019] The PQQ ionic liquid provided by this invention combines the excellent properties of pyrroloquinoline quinone (PQQ) and ionic liquids, and has broad research prospects. In addition to the separation of nuclides in the field of nuclear medicine, it can also be extended to the adsorption and separation of various metal ions, providing efficient solutions for new material preparation, environmental protection and other fields, with broad application prospects. Attached Figure Description

[0020] Figure 1 This is the tetrabutylammonium pyrroloquinoline quinone ionic liquid [TBA]3 [PQQ] of Example 2 of the present invention. 1 H-NMR spectrum.

[0021] Figure 2 This is the ESI-MS spectrum (ESI+ mode) of tetrabutylammonium pyrroloquinoline quinone ionic liquid [TBA]3[PQQ] in Example 2 of the present invention.

[0022] Figure 3 This is the ESI-MS spectrum (ESI-mode) of tetrabutylammonium pyrroloquinoline quinone ionic liquid [TBA]3[PQQ] in Example 2 of the present invention.

[0023] Figure 4The FT-IR spectra of the tetrabutylammonium pyrroloquinoline quinone ionic liquid [TBA]3 [PQQ] of Example 2, the poly(1-vinyl-3-butylimidazolium)pyrroloquinoline quinone ionic liquid P[VBIm]2 [PQQ] of Example 7, the pyrroloquinoline quinone PQQ, and the disodium salt of pyrroloquinoline quinone Na2PQQ are shown.

[0024] Figure 5 The images shown are SEM images and EDS analysis diagrams of poly(1-vinyl-3-butylimidazolium)pyrroloquinoline quinone ionic liquid P[VBIm]2[PQQ] in Example 7 of this invention, where A is the SEM image and B is the EDS analysis diagram.

[0025] Figure 6 The images show the poly(1-vinyl-3-butylimidazolium)pyrroloquinoline quinone ionic liquid P[VBIm]2[PQQ] before and after adsorption of zirconium in Example 7 of this invention. A represents the liquid before adsorption, and B represents the liquid after adsorption.

[0026] Figure 7 The XPS spectra of poly(1-vinyl-3-butylimidazolium)pyrroloquinolinequinone ionic liquid P[VBIm]2[PQQ] before and after zirconium adsorption are shown in Example 7 of this invention. A represents before adsorption, and B represents after adsorption.

[0027] Figure 8 The images shown are SEM images and EDS analysis diagrams of poly(1-vinyl-3-butylimidazolium)pyrroloquinoline quinone ionic liquid P[VBIm]2[PQQ] after zirconium adsorption in Example 7 of this invention, where A is the SEM image and B is the EDS analysis diagram. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Note: Unless otherwise specified, the experimental methods in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0030] This invention provides a pyrroloquinoline quinone (PQQ) ionic liquid comprising anions and cations, as detailed below: Wherein, the anion is the pyrroloquinoline quinone anion shown in Formula I, where n = 1, 2 or 3; The cation is any one of formulas II-V, where R1 and R3 are hydrocarbon groups with a carbon chain length of 1 to 20; R2, R4, R5, R6, R7 and R8 are hydrogen atoms, hydrocarbon groups with a carbon chain length of 1 to 20 or substituted hydrocarbon groups, wherein the substituent is at least one of hydroxyl, amino, carboxyl, ester, or sulfonic acid groups; in formulas IV and V, m1 and m2 refer to the number of repeating units, indicating that formulas IV and V are polymers.

[0031] The pyrroloquinoline quinone ionic liquid provided by this invention can be prepared by the following method: pyrroloquinoline quinone or pyrroloquinoline quinone sodium salt and the corresponding cation compound are mixed in a solvent at a ratio of 1:1 to 1:3. When the product is a clear liquid, the clear liquid is dried. When the product is a solid, the precipitate or the filter cake obtained during filtration is washed and dried to obtain the pyrroloquinoline quinone ionic liquid.

[0032] The molar ratio of pyrroloquinoline quinone to the corresponding cation, and of the sodium salt of pyrroloquinoline quinone to the corresponding cation is preferably 1:1, 1:2, and 1:3; the sodium salt of pyrroloquinoline quinone is a monosodium salt, a disodium salt, or a trisodium salt of pyrroloquinoline quinone, preferably a disodium salt of pyrroloquinoline quinone; the corresponding cation is a hydroxide or halide of formula II, III, IV, and V, and the halide can be selected from fluoride, chloride, bromide, or iodide, preferably bromide; the solvent can be selected from at least one of water, acetonitrile, methanol, ethanol, isopropanol, and acetone, preferably water, methanol, and / or ethanol.

[0033] The solvent can be selected from at least one of toluene, dichloromethane, ethyl acetate, acetone, isopropanol, ethanol, methanol, acetonitrile, and water.

[0034] The reaction temperature is from room temperature to 100 °C, preferably room temperature; the reaction time is 1 to 72 hours.

[0035] The separation process can be achieved by direct filtration or centrifugation, or by adding a solvent followed by filtration or centrifugation, at least one of the following:

[0036] Example 1: Preparation of Ionic Liquids The tetraethylammonium pyrroloquinoline quinone ionic liquid [TEA]2[PQQ] was synthesized, wherein the cation is of formula III above, wherein R3, R4, R5 and R6 are all -C2H5; and the anion is of formula I, wherein n = 2.

[0037] The [TEA]2[PQQ] ionic liquid was obtained by mixing 2.36 g (4 mmol) of tetraethylammonium hydroxide aqueous solution (25 wt%) with 0.660 g (2 mmol) of pyrroloquinoline quinone, stirring at room temperature for 12 h, centrifuging to remove the solid, collecting the supernatant, removing the solvent, and obtaining the [TEA]2[PQQ] ionic liquid.

[0038] Example 2 Preparation of Ionic Liquids The tetrabutylammonium pyrroloquinoline quinone ionic liquid [TBA]3[PQQ] was synthesized, wherein the cation is of formula III above, wherein R3, R4, R5 and R6 are all -C4H9, and the anion is of formula I, wherein n=3.

[0039] The [TBA]3[PQQ] ionic liquid was obtained by mixing 3.10 g (3 mmol) of tetrabutylammonium hydroxide aqueous solution (25 wt%) with 0.330 g (1 mmol) of pyrroloquinoline quinone, stirring at room temperature for 24 h, centrifuging to remove the solid, collecting the supernatant, removing the solvent, and obtaining the 1H NMR spectrum. The results are shown in the figure. Figure 1 As shown; further analysis yielded the ESI+ and ESI- modes of the ESI-MS spectrum of this ionic liquid, as shown in the figure. Figure 2 and Figure 3 As shown.

[0040] Example 3 Preparation of Ionic Liquids Synthesize hexadecyltrimethylammonium pyrroloquinoline quinone ionic liquid [CTMA]2[PQQ], wherein the cation is of formula III above, and R3 is -C 16 H 33 R4, R5 and R6 are all -CH3, and the anion is of formula I, where n = 2.

[0041] The [CTMA]2[PQQ] ionic liquid was obtained by mixing 3.02 g (1 mmol) of hexadecyltrimethylammonium hydroxide aqueous solution (10 wt%) with 0.165 g (0.5 mmol) pyrroloquinoline quinone, stirring at room temperature for 30 h, centrifuging to remove the solid, collecting the supernatant, removing the solvent, and obtaining the [CTMA]2[PQQ] ionic liquid.

[0042] Example 4: Preparation of Ionic Liquids Synthesize (2-hydroxyethyl)trimethylammonium pyrroloquinolinequinone ionic liquid [Ch]2[PQQ], wherein the cation is of formula III above, wherein R3 is -C2H4OH, and R4, R5 and R6 are all -CH3, and the anion is of formula I, wherein n = 2.

[0043] The solid was removed by mixing 0.969 g (4 mmol) of (2-hydroxyethyl)trimethylammonium hydroxide aqueous solution (50 wt%) with 0.660 g (2 mmol) of pyrroloquinoline quinone, stirring at room temperature for 15 h, centrifuging to remove the solid, collecting the supernatant, removing the solvent, and obtaining the [Ch]2[PQQ] ionic liquid.

[0044] Example 5 Preparation of Ionic Liquids Synthesize 1-butyl-3-methylimidazolium pyrroloquinoline quinone ionic liquid [BMIm]2[PQQ], wherein the cation is of formula II above, where R1 is -CH3 and R2 is -C4H9, and the anion is of formula I, where n = 2.

[0045] The [BMIm]2[PQQ] ionic liquid was obtained by mixing an ethanol solution containing 0.625 g (4 mmol) of 1-butyl-3-methylimidazolium hydroxide (synthesized by the method in the reference, Journal of Materials Chemistry A 2024, 12, 8747) with 0.660 g (2 mmol) of pyrroloquinoline quinone, stirring at room temperature for 15 h, centrifuging to remove the solid, collecting the supernatant, removing the solvent, and obtaining the [BMIm]2[PQQ] ionic liquid.

[0046] Example 6 Preparation of Ionic Liquids Example 6 The poly(1-vinyl-3-ethylimidazolium)pyrroloquinolinequinone ionic liquid P[VEIm]3[PQQ] was synthesized, wherein the cation is of formula IV above, wherein R7 is -C2H5, and the anion is of formula I, wherein n = 3.

[0047] The P[VEIm]3[PQQ] ionic liquid was obtained by mixing an aqueous solution containing 1.22 g (6 mmol) of poly(1-vinyl-3-ethylimidazolium) bromide (synthesized by the method in the reference, Chemical Communications, 2024, 60, 14041) with an aqueous solution containing 0.748 g (2 mmol) of disodium pyrroloquinoline quinone, stirring at room temperature for 15 h, filtering under reduced pressure and retaining the filter cake, washing with deionized water to remove residual solvent.

[0048] Example 7 Preparation of Ionic Liquids Example 7 The poly(1-vinyl-3-butylimidazolium)pyrroloquinolinequinone ionic liquid P[VBIm]2[PQQ] was synthesized, wherein the cation is of formula IV above, wherein R7 is -C4H9, and the anion is of formula I, wherein n=2.

[0049] By mixing an ethanol solution containing 0.673 g (4 mmol) of poly(1-vinyl-3-butylimidazolium) hydroxide with 0.660 g (2 mmol) of pyrroloquinoline quinone, stirring at room temperature for 24 h, centrifuging to remove the supernatant, collecting the solid fraction, washing with deionized water to remove residual solvent, and obtaining P[VBIm]2[PQQ] ionic liquid.

[0050] Further FT-IR spectra of tetrabutylammonium pyrroloquinoline quinone ionic liquid [TBA]3 [PQQ] in Example 2, poly(1-vinyl-3-butylimidazolium)pyrroloquinoline quinone ionic liquid P[VBIm]2 [PQQ], pyrroloquinoline quinone PQQ, and pyrroloquinoline quinone disodium salt Na2PQQ in Example 7 were determined. The results are shown in […]. Figure 4 As shown.

[0051] SEM and EDS analyses were performed on the poly(1-vinyl-3-butylimidazolium)pyrroloquinoline quinone ionic liquid P[VBIm]2[PQQ]. The results are shown in the figures below. Figure 5 As shown in Figures A and B, where A is the SEM image and B is the EDS analysis image.

[0052] Photos were taken of the ionic liquid P[VBIm]2[PQQ] before and after the adsorption of zirconium. The results are shown below. Figure 6 As shown in Figures A and B, where A represents the state before adsorption and B represents the state after adsorption.

[0053] XPS spectra of the ionic liquid P[VBIm]2[PQQ] before and after zirconium adsorption were analyzed, and the results are shown in the figure. Figure 7 As shown in Figures A and B, where A represents the adsorption state and B represents the adsorption state before adsorption.

[0054] Zirconium adsorbed on the ionic liquid P[VBIm]2[PQQ] was analyzed by SEM and EDS. The results are shown in the figures below. Figure 8 As shown in Figures A and B, where A is the SEM image and B is the EDS analysis image. Example 8 Preparation of Ionic Liquids The poly(N-ethyl-4-vinylpyridinium)pyridinequinolinequinone ionic liquid P[VEPy]2[PQQ] was synthesized, wherein the cation is of formula V above, wherein R8 is -C2H5, and the anion is of formula I, wherein n=2.

[0055] The P[VMPy]2[PQQ] ionic liquid was obtained by mixing an ethanol solution containing 0.856 g (4 mmol) of brominated poly(N-ethyl-4-vinylpyridinium) (synthesized by the method in the reference, Journal of Membrane Science 2010, 347(1-2), 183) with an aqueous solution containing 0.748 g (2 mmol) of disodium pyrroloquinoline quinone, stirring at room temperature for 24 h, filtering under reduced pressure and retaining the filter cake, washing with deionized water to remove the solvent.

[0056] Example 9 Preparation of Ionic Liquids Example 9 The glycine-pyrroloquinolinequinone ionic liquid [Gly][PQQ] was synthesized, wherein the cation is of formula III above. R3, R4, and R5 are -H, R6 is -C2H3O2, and the anion is of formula I, where n = 1.

[0057] The [Gly][PQQ] ionic liquid was obtained by mixing an aqueous solution containing 0.150 g (2 mmol) glycine with 0.660 g (2 mmol) pyrroloquinoline quinone, stirring at room temperature for 12 h, centrifuging to remove the solid, collecting the supernatant, removing the solvent, and obtaining the [Gly][PQQ] ionic liquid.

[0058] Example 10 Preparation of Ionic Liquids Example 10 Synthesize isoleucine-pyrroloquinolinequinone ionic liquid [Ile][PQQ], wherein the cation is of formula III above, R3, R4, and R5 are -H, and R6 is -C6H. 11 O2, the anion is of formula I, where n = 1.

[0059] The [Ile][PQQ] ionic liquid was obtained by mixing an aqueous solution containing 0.262 g (2 mmol) of isoleucine with 0.660 g (2 mmol) of pyrroloquinoline quinone, stirring at room temperature for 12 h, centrifuging to remove the solid, collecting the supernatant, removing the solvent, and obtaining the [Ile][PQQ] ionic liquid.

[0060] Example 11 Preparation of Ionic Liquids Example 11 Synthesize tryptophan methyl ester pyrroloquinoline quinone ionic liquid [Trp-mE]2[PQQ], wherein the cation is of formula III above, R3, R4, and R5 are -H, and R6 is -C. 12 H 12 NO2, the anion is represented by formula I, where n = 2.

[0061] By mixing 0.873 g (4 mmol) of tryptophan methyl ester with 0.660 g (2 mmol) of pyrroloquinoline quinone in methanol as the reaction solvent, stirring at room temperature for 24 h, centrifuging to remove the solid, collecting the supernatant, and removing the solvent, the [Trp-mE]2[PQQ] ionic liquid was obtained.

[0062] Example 12 Applicability Verification of Ionic Liquids 1 Poly(1-vinyl-3-butylimidazolium)pyrroloquinoline quinone ionic liquid—P[VBIm]2[PQQ]—is used for yttrium-zirconium separation experiments.

[0063] Weigh 200 mg of P[VBIm]2[PQQ] prepared by the aforementioned method, mix thoroughly with 1 g of silica gel, and pack into a separation column with an inner diameter of 1 cm. Add 10 mL of a mixed solution containing 20 mg / L zirconium and 10 g / L yttrium. After sufficient contact, first rinse with 50 mL of deionized water, then rinse with 50 mL of 0.5 mol / L silica gel. -1 The oxalic acid solution was eluted at a rate of 0.5 mL / min.

[0064] The concentrations of yttrium and zirconium in the oxalic acid eluent were determined to be 0.062 mg / L and 2.756 mg / L, respectively, using inductively coupled plasma atomic emission spectrometry (ICP-AES). Based on the measurement results, the purity P of Zr in the eluent was calculated. Zr The recovery rate of Zr is 98%, R Zr It is 69%.

[0065] Example 13 Applicability Verification of Ionic Liquids 2 Poly(N-ethyl-4-vinylpyridinium)pyrroloquinolinequinone ionic liquid—P[VEPy]2[PQQ]—is used for strontium-yttrium separation experiments.

[0066] Weigh 250 mg of P[VEPy]2[PQQ] prepared using the aforementioned method, mix thoroughly with 1 g of diatomaceous earth, and pack into a separation column with an inner diameter of 1 cm. Add 5 mL of a mixed solution containing 10 g / L strontium and 25 mg / L yttrium. After sufficient contact, first rinse with 50 mL of deionized water, then rinse with 50 mL of 0.5 mmol / L... -1 The aqueous solution of disodium ethylenediaminetetraacetate was eluted at a rate of 0.5 mL / min.

[0067] The concentrations of strontium and yttrium in the disodium ethylenediaminetetraacetate eluent were determined to be 0.108 mg / L and 2.046 mg / L, respectively, using inductively coupled plasma atomic emission spectrometry (ICP-AES). Based on the measurement results, the purity P of Y in eluent 2 was calculated. Y The recovery rate of Y is 95%, R YIt is 82%.

[0068] Comparative Example 1 Brominated poly(1-vinyl-3-butylimidazolium) ionic liquid, namely P[VBIm][Br], is used in yttrium zirconium separation experiments.

[0069] Weigh 200 mg of P[VBIm][Br], mix thoroughly with 1 g of silica gel, and pack into a separation column with an inner diameter of 1 cm. Other steps are the same as in Example 12. During the process, the stationary phase material gradually dissolves, forming a viscous solid-liquid mixture that hinders the flow of the mobile phase, making it unsuitable for column chromatography separation.

[0070] Comparative Example 2 Disodium pyrroloquinoline quinone was used in yttrium zirconium separation experiments.

[0071] Weigh 200 mg of disodium pyrroloquinoline quinone, mix thoroughly with 1 g of silica gel, and pack into a separation column with an inner diameter of 1 cm. Other steps are the same as in Example 12. During the process, the stationary phase gradually turns red, and a dark red solution flows out of the separation column with the action of the peristaltic pump, resulting in direct loss. This method is not suitable for column chromatography separation.

[0072] Comparative Example 3 Pyrroloquinoline quinone (PQQ) was used in yttrium zirconium separation experiments.

[0073] Weigh 200 mg of pyrroloquinoline quinone, mix thoroughly with 1 g of silica gel, and pack into a separation column with an inner diameter of 1 cm. Other steps are the same as in Example 12. During the process, the stationary phase gradually turns red, and a bright red solution flows out of the separation column with the action of the peristaltic pump, resulting in direct loss. This method is not suitable for column chromatography separation.

[0074] Comparative Example 4 Silica gel is used in yttrium zirconium separation experiments.

[0075] Weigh 1 g of silica gel and pack it into a separation column with an inner diameter of 1 cm. Add 10 mL of a mixed solution containing 20 mg / L zirconium and 10 g / L yttrium. After sufficient contact, rinse with deionized water at a rate of 0.5 mL / min. Collect 10 mL solutions as one group, and collect a total of 8 groups. The concentrations of yttrium and zirconium in the water eluent were determined by inductively coupled plasma atomic emission spectrometry. The results are shown in Table 1.

[0076] Table 1. Concentrations of yttrium and zirconium in the effluent when silica gel is used as the stationary phase and water is used as the mobile phase. Calculations based on measurement results show that when the original solution passes through the separation column, ~96% of yttrium and ~76% of zirconium flow out with the eluent, and a large amount of zirconium flows out almost simultaneously with yttrium, making effective separation impossible. Compared with Example 12, it is evident that the silica gel itself, as the column packing matrix, does not play a crucial role in the separation of yttrium and zirconium; P[VBIm]2[PQQ] is the core component for achieving highly selective separation.

[0077] Comparative Example 5 Brominated poly(N-ethyl-4-vinylpyridinium) was used in strontium-yttrium separation experiments.

[0078] 250 mg of poly(N-ethyl-4-vinylpyridinium) bromide was weighed and thoroughly mixed with 1 g of diatomaceous earth. The mixture was then packed into a separation column with an inner diameter of 1 cm. The water eluent and the disodium ethylenediaminetetraacetate (EDTA-2Na) eluent were collected separately, and the rest was the same as in Example 13. The concentrations of strontium and yttrium in the eluent were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), and the results are shown in Table 2.

[0079] Table 2. Concentrations of Strontium and Yttrium in the effluent when brominated poly(N-ethyl-4-vinylpyridinium) is used as the stationary phase. Table 2 shows that when brominated poly(N-ethyl-4-vinylpyridinium) is used as the stationary phase, approximately 90% of the strontium flows out with the eluent and cannot stably bind with the stationary phase. Furthermore, strontium and yttrium flow out simultaneously, making it impossible to directly obtain high-purity yttrium. Therefore, brominated poly(N-ethyl-4-vinylpyridinium) does not meet the requirements... 90 Sr- 90 The requirements for stationary phase materials in the Y generator prevent the direct use of such materials.

[0080] Comparative Example 6 Disodium pyrroloquinoline quinone was used in the separation of strontium and yttrium.

[0081] Weigh 250 mg of disodium pyrroloquinoline quinone and mix it thoroughly with 1 g of diatomaceous earth. Then pack the mixture into a separation column with an inner diameter of 1 cm. Other steps are the same as in Example 13. During the process, the stationary phase gradually turns red, and a dark red solution flows out of the separation column with the action of the peristaltic pump, resulting in direct loss. This method is not suitable for column chromatography separation.

[0082] Comparative Example 7 Pyrroloquinoline quinone was used in the separation of strontium and yttrium.

[0083] Weigh 250 mg of pyrroloquinoline quinone, mix thoroughly with 1 g of diatomaceous earth, and pack into a separation column with an inner diameter of 1 cm. Other steps are the same as in Example 13. During the process, the stationary phase gradually turns red, and a bright red solution flows out of the separation column with the action of the peristaltic pump, resulting in direct loss. This method is not suitable for column chromatography separation.

[0084] Comparative Example 8 Diatomaceous earth is used in strontium-yttrium separation experiments.

[0085] Weigh 1 g of diatomaceous earth and pack it into a separation column with an inner diameter of 1 cm. Add 5 mL of a mixed solution containing 10 g / L strontium and 25 mg / L yttrium. After sufficient contact, elute with 50 mL of deionized water at a rate of 0.5 mL / min. Collect 10 mL eluents as one group, for a total of 8 groups. Detect the concentrations of strontium and yttrium in the eluent using ICP-OES. The results are shown in Table 3.

[0086] Table 3. Concentrations of Strontium and Yttrium in the effluent when diatomaceous earth is used as the stationary phase and water as the mobile phase. Calculations based on the measurement results show that when the original solution passes through the separation column, ~96% of the strontium and ~85% of the yttrium flow out with the eluent, resulting in a significant loss of strontium. Although the yttrium flows out more slowly, it cannot be effectively separated from the strontium. A comparison with Example 13 shows that diatomaceous earth, as the column packing matrix, does not play a crucial role in the separation of strontium and yttrium.

[0087] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A pyrroloquinoline quinone ionic liquid, characterized in that, The ionic liquid contains anions and cations; The anion is the pyrroloquinoline quinone anion shown in Formula I, where n = 1, 2 or 3; The cation is any one of formula II, formula III, formula IV or formula V: wherein, in formula II, R1is a C1-C 20 hydrocarbyl group, and R2is any of hydrogen, a C1-C 20 hydrocarbyl group or a substituted hydrocarbyl group; In Equation III, R3 is C1-C 20 The hydrocarbon group, R4, R5, and R6 are hydrogen, C1-C 20 Any one of the hydrocarbon groups or substituted hydrocarbon groups; In formula IV, R7 is hydrogen, C1-C 20 Any one of the hydrocarbon groups or substituted hydrocarbon groups; In formula V, R8 represents hydrogen and C1-C. 20 Any one of the hydrocarbon groups or substituted hydrocarbon groups; The substituent of the substituted hydrocarbon group is at least one selected from hydroxyl, amino, carboxyl, ester, and sulfonic acid groups; In formulas IV and V, m1 and m2 refer to the number of repeating units, indicating that formulas IV and V are polymers.

2. The pyrroloquinoline quinone ionic liquid according to claim 1, characterized in that, The compound corresponding to the cation is a hydroxide or halide of formula II-V, and the halide is a fluoride, chloride, bromide or iodide.

3. The method for preparing the pyrroloquinoline quinone ionic liquid according to any one of claims 1-2, characterized in that, The pyrroloquinoline quinone or its sodium salt is mixed with the corresponding cation in a solvent at a molar ratio of 1:1 to 1:

3. After the reaction, the mixture is separated and dried to obtain the pyrroloquinoline quinone ionic liquid.

4. The preparation method according to claim 3, characterized in that, The sodium salt of pyrroloquinoline quinone is a monosodium salt, a disodium salt, or a trisodium salt of pyrroloquinoline quinone; the solvent is selected from at least one of water, acetonitrile, methanol, ethanol, isopropanol, and acetone.

5. The preparation method according to claim 3, characterized in that, The reaction temperature is from room temperature to 100°C, and the reaction time is from 1 to 72 hours.

6. The preparation method according to claim 3, characterized in that, The separation method is at least one of direct filtration, centrifugation, or filtration and centrifugation after adding solvent. When the product is a clear liquid, the clear liquid is dried. When the product is a solid, the precipitate or the filter cake obtained during filtration is washed and dried.

7. The application of the pyrroloquinoline quinone ionic liquid according to any one of claims 1 or 2 in the adsorption and separation of metal ions.

8. The application according to claim 7, characterized in that, The metal ions include at least one of zirconium ions, yttrium ions, and strontium ions.

9. The application according to claim 7, characterized in that, The pyrroloquinoline quinone ionic liquid is mixed with a support and then loaded into a separation column for column chromatography separation of metal ions.

10. The application according to claim 9, characterized in that, The carrier can be selected from at least one porous carrier material selected from silica gel, diatomaceous earth, zeolite, alumina, molecular sieve, and resin. The eluent for column chromatography separation is selected from at least one of oxalic acid, disodium ethylenediaminetetraacetate, diethylenetriaminepentaacetic acid, potassium chloride, calcium chloride, hydrochloric acid, and nitric acid solution.

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