Preparation method of metal organic gel based on metal sulfur clusters

Abstract

The invention belongs to the field of organic-inorganic hybrid aerogel materials, and particularly relates to metal organic gel based on metal sulfur clusters and a preparation method of the metal organic gel. According to the metal organic gel based on the metal sulfur cluster, a sulfur-containing metal cluster ligand is used as a precursor and is combined with an organic ligand under alkali regulation; the precursor is MS-X, X is halogen, and M is transition metal. A specific organic ligand is dehydrogenated under an alkali-induced reaction, the dehydrogenated organic linker further replaces halogen Br on the periphery of a precursor to form gel, and then the novel sulfur cluster-based metal organic gel is obtained through freeze drying or supercritical drying.

Description

Technical Field

[0001] The present invention belongs to the field of organic-inorganic hybrid aerogel materials, and particularly relates to a metal-organic gel based on metal sulfide clusters and a preparation method thereof. Background Art

[0002] In recent years, the research on gels has attracted great interest. The formation of supramolecular gels is mainly driven by non-covalent bond forces such as hydrogen bonds, π-π interactions, and van der Waals forces, and they assemble into anisotropic three-dimensional network structures in solution. The composition of gels contains up to 97% solvent and a small amount of solid (gelator), and the solvent molecules are fixed in the gel matrix formed by the self-assembly of the gelator. According to the different forces, gels are divided into physical gels and chemical gels. Among them, supramolecular gels belong to physical gels, while chemical gels formed by strong covalent bonds are irreversible and have good thermal stability. As one of the porous materials favored by everyone, gels have been widely used due to their high specific surface area, good thermal stability and other characteristics. For example, physical gels can be used as stimulus-responsive materials and applied in fields such as sensing and drug release, while chemical gels can be applied in fields such as catalysis, dye adsorption, and substance separation.

[0003] Among them, Metal Organic Gels (MOGs) are viscoelastic and solid-like materials assembled by metal-organic coordination and other intermolecular forces (π-π stacking, hydrogen bonding, etc.). They are homologous to Metal Organic Frameworks (MOFs) and are also a kind of coordination-driven supramolecular polymer. Due to the characteristics of MOGs such as high porosity, low density, high specific surface area, and a large number of Lewis acid sites, and their diverse chemical structural properties, they have gradually become a research hotspot in current research. They show broad application prospects in the fields of adsorption, catalysis, drug release, sensing, etc. For example, in 2023, Li et al. (ACS Appl. Mater. Interfaces 2020, 12, 41359-41367) developed a Cu-doped two-dimensional carbon material C3N4 (Cu-C3N4-550) with excellent catalytic performance by directly pyrolyzing a Cu(II) metal organic gel (MOG) precursor and melamine. Due to the sufficient metal active sites and high specific surface area of the prepared Cu-C3N4-550, -OH is generated in the catalytic reaction, so it has excellent peroxidase-like activity and is used for the detection of alkaline phosphatase. In 2021, Wang et al. (Applied Catalysis B: Environmental 2021, 299, 120641) reported a novel coordination polymer catalyst through a simple one-step aqueous phase synthesis method. MOGs containing nitrogen tricarboxylic acid ligands and various metal salts were prepared by freeze-drying at room temperature and atmospheric pressure, achieving efficient electrocatalytic water splitting. On the other hand, MOGs can be templated to obtain other structures, especially porous materials. This is achieved by polymerizing, precipitating, or reducing the precursors in the liquid phase, and then removing the gel network by dissolution or calcination. The property of using the gel to template porous metal oxides from soluble precursors and bulk metals themselves, and introducing metals into the gel network and liquid components provides a wide range of possibilities for controlling different material morphologies.

[0004] Although people have made surprising application progress in many fields by using metal-organic gels, precisely due to the overly free assembly, during the formation of the gels, due to the structural uncertainty caused by coordination and other influencing factors, constructing and designing specific functional metal-organic gels still pose quite a challenge for application research. At the same time, during the preparation of the gels, the preparation conditions are complex, and the curing process generally requires a long time, which greatly reduces the production efficiency. Therefore, rationally designing and preparing functional metal-organic gel materials with well-defined structures, simple methods, short preparation cycles, and high stability remains a huge challenge. During the synthesis process, factors such as temperature control, selection of suitable solvents, ratio between reactants, and pH all affect whether MOGs can be successfully synthesized in the end. So far, people's understanding of the synthesis rules of MOGs is still in the exploratory stage, and exploring the applications of MOGs with specific functional properties poses great challenges and difficulties. Summary of the Invention

[0005] To solve the deficiencies of the prior art, the purpose of the present invention is to provide a metal-organic gel based on metal sulfide clusters and its preparation method, which are simple, effective, have a well-defined structure, and have a certain systematicness.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A metal-organic gel based on metal sulfide clusters, where the metal-organic gel uses a sulfur-containing metal cluster ligand as a precursor and combines with an organic ligand under the regulation of an alkali; the precursor is MS-X, where X is a halogen and M is a transition metal.

[0008] Preferably, M is Mo or Fe.

[0009] The organic linker is a thiol and / or carboxylic acid organic compound; among them, there is a certain molar ratio between the precursor and the organic linker, which depends on the proportion of the reaction groups of the two. Among them, the precursor is counted by halogen atoms, the organic linker is counted by mercapto or carboxyl groups, and the molar ratio of halogen to mercapto or carboxyl is in the range of 1:0.8 - 1:2.5.

[0010] Preferably: when the precursor is a molybdenum sulfide cluster, the number of halogens is 6, the mercapto group in the organic ligand 1,4-benzenedithiol is 2, and the optimal molar ratio is 1:3.

[0011] The thiol organic compound is one or more of 1,4-benzenedithiol (BDT), biphenyl-4,4'-dithiol, 1,4-benzenedimethanethiol, 1,2-benzenedithiol, 1,3-benzenedithiol, 2,5-diamino-1,4-benzenedithiol, pyridine-2,6-dithiol, ethanedithiol, propanedithiol; preferably 1,4-benzenedithiol (BDT), biphenyl-4,4'-dithiol.

[0012] The carboxylic acid organic compound is one or more of terephthalic acid, isophthalic acid, phthalic acid, 2-aminoterephthalic acid, 2,5-thiophenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, 4,4'-stilbenedicarboxylic acid, [1,1:4,1-terphenyl]-4,4'-dicarboxylic acid. Preferably, it is terephthalic acid, isophthalic acid, 4,4'-biphenyldicarboxylic acid.

[0013] A preparation method of the metal-organic gel based on metal sulfide clusters uses a sulfur-containing metal cluster ligand as a precursor, which combines with an organic ligand under the regulation of an alkali to form a uniform and porous sulfur cluster-based metal-organic sulfide gel.

[0014] Furthermore,

[0015] 1) Dissolve the sulfur-containing metal cluster ligand as a precursor and the organic ligand in an organic solvent and mix them evenly to obtain Solution 1;

[0016] 2) Add an alkali solution to the above Solution 1 and mix well to obtain Solution 2;

[0017] 3) Let the obtained Solution 2 stand still at a corresponding temperature and time to allow the ligand substitution reaction to complete, and obtain a wet gel through solvent substitution, and then dry it to obtain the metal-organic gel of metal sulfide clusters.

[0018] The addition sequence in the preparation process can also be: adding the precursor, the organic solution of the organic linker, and the organic solution of the alkali to each other; or adding the organic solution of the precursor, the organic linker, and the organic solution of the alkali to each other; or adding the precursor, the organic solution of the alkali, and the organic linker to each other.

[0019] In the above step 1), the organic solvent is N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), dimethyl sulfoxide (DMSO), or acetonitrile; the alkali can be an organic base or an inorganic base.

[0020] Preferably, the alkali is one or more of pyridine, triethylamine, diethylamine, ammonia water, sodium ethanethiolate, 4-dimethylaminopyridine, 2-methylpyridine, and diisopropylamine.

[0021] In the above step 3), let the obtained Solution 2 stand still at 0-120 °C for 0.15-48 hours through the ligand substitution reaction to obtain a wet gel, and then dry it to obtain the metal-organic gel of metal sulfide clusters.

[0022] The addition amount of the above solvent: calculated based on the proportion of the precursor in all solvents in the reaction system, the range is 5 - 20 mg / mL; the addition amount of the base: calculated based on the molar ratio of the organic linker to the base, the range is 1:0.8 - 1:15; the addition rate of the base is calculated based on the addition rate of the organic solution of the base.

[0023] After the wet gel is formed, solvent replacement is carried out until the original organic solvent is completely replaced.

[0024] The solvent replacement is carried out by alternately treating with absolute ethanol and aqueous ethanol solution.

[0025] An application of the metal-organic gel based on metal sulfide clusters as described above, characterized in that: the application of the organic gel in iodine vapor adsorption.

[0026] One or more embodiments of the present invention have at least the following beneficial effects:

[0027] 1) In the present invention, dehydrogenation of a specific organic ligand occurs under the induction of a base reaction. After dehydrogenation, the organic linker further replaces the halogen Br on the periphery of the precursor to form a gel, and then a novel sulfur cluster-based metal-organic gel is obtained through freeze-drying or supercritical drying.

[0028] 2) In the present invention, in a specific organic reaction system, a specific base is used as an initiator to induce the dehydrogenation reaction of the mercapto or carboxyl group in the organic ligand, and then further replaces the halogen Br on the periphery of the precursor, thereby forming a novel sulfur cluster-based metal-organic gel that retains the main structure of the organic ligand and the precursor.

[0029] 3) The preparation of the present invention is simple, the raw materials are easily available, economical and environmentally friendly, and a new method for preparing organic-inorganic hybrid chalcogen metal-organic gels is provided through a rapid ligand replacement reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The specification drawings constituting a part of the present invention are used to provide a further understanding of the present application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention (the drawings are all from Examples 1 and 3, named BDT-MOSG and BDC-MOSG respectively).

[0031] Figure 1 Solid nuclear magnetic resonance provided for the embodiments of the present invention 13 C spectrum: molybdenum-sulfur cluster, organic linker (BDT or BDC), Example 1 (BDT-MOSG), Example 3 (BDC-MOSG).

[0032] Figure 2 Morphology test provided for the embodiments of the present invention: (a) optical photograph of Example 1, (b)-(c) scanning electron microscope images, (d)-(e) transmission electron microscope images, (f) EDS element distribution map.

[0033] Figure 3 Fourier transform infrared spectroscopy provided by the embodiments of the present invention: molybdenum-sulfur clusters, organic linkers (BDT or BDC), Example 1 (BDT-MOSG), Example 3 (BDC-MOSG).

[0034] Figure 4 X-ray diffraction pattern (XRD) provided by the embodiments of the present invention: Example 1 (BDT-MOSG), Example 3 (BDC-MOSG).

[0035] Figure 5 X-ray photoelectron spectroscopy (XPS) test provided by the embodiments of the present invention: molybdenum-sulfur clusters, Example 1 (BDT-MOSG), Example 3 (BDC-MOSG).

[0036] Figure 6 Nitrogen isothermal adsorption and desorption test provided by the embodiments of the present invention: Example 1

[0037] (BDT-MOSG), Example 3 (BDC-MOSG).

[0038] Figure 7 Sample display pictures provided for the comparative examples of the present invention.

[0039] Figure 8 Comparison of gel adsorption performance with others provided for the application examples of the present invention. Detailed Description of the Invention

[0040] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which the present disclosure belongs.

[0041] In order to enable those skilled in the art to more clearly understand the technical solutions of the present invention, the technical solutions of the present invention will be described in detail below in conjunction with specific embodiments.

[0042] The metal-sulfur cluster precursors used in the following examples have the following structures, and the preparation methods can be found in the literature Science China Materials 2022, 65, 1294-1302, Journal of the American Chemical

[0043] Society 2019, 141, 3940-3951. Among them, (a) MoS-X; (b) FeS-X:

[0044]

[0045] Example 1

[0046] 1) Add 47.0 mg of MoS-Br and 16.0 mg of 1,4-benzenedithiol (BDT) into 2.0 mL of N,N-dimethylformamide (DMF), and ultrasonicate for 2 - 5 min to obtain Solution 1.

[0047] 2) Take 0.1 mL of triethylamine and add it into 2.0 mL of DMF, mix well to obtain Solution 2.

[0048] 3) Mix Solution 1 and 2 well and let it stand at room temperature for 2 h.

[0049] 4) Solvent replacement (pour out the remaining DMF, replace the solvent with absolute ethanol, and change the solvent 3 - 5 times a day (on the first day: ethanol, on the second day: ethanol / water (1:1, V / V), on the third day: absolute ethanol). 5) Subject the obtained wet gel to supercritical freeze-drying (see Figures 1-6 ).

[0050] As can be seen from Figures 1-6 , the obtained MOGs exhibit an amorphous porous structure, and the organic ligands and the precursor main structure of the clusters are completely retained, and the distribution of each component is uniform.

[0051] Example 2

[0052] 1) Add 47.0 mg of MoS-Br and 16 mg of BDT into 2 mL of N,N-dimethylformamide (DMF), and ultrasonicate for 2 - 5 min to obtain Solution 1.

[0053] 2) Take 0.05 mL of triethylamine and add it into 2 mL of DMF, mix well to obtain Solution 2.

[0054] 3) Mix Solution 1 and 2 well and let it stand at room temperature for 2 h.

[0055] 4) Solvent replacement (pour out the remaining DMF, replace the solvent with absolute ethanol, and change the solvent 3 - 5 times a day (on the first day: ethanol, on the second day: ethanol / water (1:1, V / V), on the third day: absolute ethanol). 5) Subject the obtained wet gel to supercritical freeze-drying.

[0056] Example 3

[0057] 1) Add 47.0 mg of MoS-Br and 19 mg of terephthalic acid (BDC) into 2.0 mL of N,N-dimethylformamide (DMF), and ultrasonicate for 2 - 5 min to obtain Solution 1.

[0058] 2) Take 0.1 mL of triethylamine and add it into 2.0 mL of DMF, mix well to obtain Solution 2.

[0059] 3) Mix Solution 1 and Solution 2 evenly and let it stand at 100 °C for 2 h.

[0060] 4) Solvent replacement (pour out the remaining DMF, replace the solvent with absolute ethanol, and change the solvent 3 - 5 times a day (on the first day: ethanol, on the second day: ethanol / water (1:1, V / V), on the third day: absolute ethanol). 5) Subject the obtained wet gel to supercritical freeze-drying (see Figures 1-6 ).

[0061] As can be seen from Figures 1-6 , the obtained MOGs present an amorphous porous structure, and the organic ligands and the precursor main structure of the clusters are completely retained, and the distribution of each component is uniform.

[0062] Example 4

[0063] 1) Add 65.40 mg of FeS-Br and 16 mg of BDT to 2.0 mL of N,N-dimethylformamide (DMF), and ultrasonicate for 2 - 5 min to obtain Solution 1.

[0064] 2) Take 0.1 mL of triethylamine and add it to 2.0 mL of DMF, and ultrasonicate for 2 - 5 min to obtain Solution 2.

[0065] 3) Mix Solution 1 and Solution 2 evenly and let it stand at 60 °C for 2 h.

[0066] 4) Solvent replacement (pour out the remaining DMF, replace the solvent with absolute ethanol, and change the solvent 3 - 5 times a day (on the first day: ethanol, on the second day: ethanol / water (1:1, V / V), on the third day: absolute ethanol). 5) Subject the obtained wet gel to supercritical freeze-drying.

[0067] Comparative Example

[0068] 1) Add 47.0 mg of MoS-Br and 16 mg of BDT to 2 mL of N,N-dimethylformamide (DMF), and ultrasonicate for 2 - 5 min to obtain Solution 1.

[0069] 2) Take 0.5 mL of triethylamine and add it to 2 mL of DMF, mix evenly to obtain Solution 2.

[0070] 3) Mix Solution 1 and Solution 2 evenly and let it stand at room temperature for 2 h.

[0071] 4) Solvent replacement (pour out the remaining DMF, replace the solvent with absolute ethanol, and change the solvent 3 - 5 times a day (on the first day: ethanol, on the second day: ethanol / water (1:1, V / V), on the third day: absolute ethanol) (see Figure 7 ).

[0072] As can be seen from Figure 7It can be seen that when the addition amount of the base is too large, due to the too fast reaction rate, the gel state cannot be formed, and thus the porous aerogel cannot be prepared by supercritical drying.

[0073] Application Example

[0074] 1) Place 20 mg of the MOGs obtained in the above Examples 1 and 3 and various commercial MOGs and 800 mg of solid iodine in a 5 mL sample bottle.

[0075] 2) Place 1 in an oven at 75 °C and weigh the MOGs every 2 hours.

[0076] 3) When the weights of the MOGs are the same after three weighings, stop the adsorption test. Calculate the maximum iodine adsorption amount based on the weight change (see Figure 8 ).

[0077] It can be seen from Figure 8 that the iodine vapor adsorption performance of the BDC-MOSG prepared in Example 3 is comparable to the optimal adsorption performance of the reported gels; the iodine vapor adsorption performance of the BDT-MOSG prepared in Example 1 is much better than the currently reported gels.

Claims

1. A metal-organic gel based on metal sulfide clusters, characterized in that: The metal-organic gel is formed by combining a sulfur-containing metal cluster ligand as a precursor with an organic ligand under the regulation of a base; the precursor is MS-X, where X is a halogen and M is a transition metal.

2. The metal-organic gel based on metal sulfide clusters according to claim 1, characterized in that: The organic linker is a thiol and / or carboxylic acid organic compound; wherein, based on the halogen atoms of the precursor and the mercapto or carboxyl groups of the organic linker, the molar ratio of halogen to mercapto or carboxyl is in the range of 1:0.8 - 1:2.

5.

3. The metal-organic gel based on metal sulfide clusters according to claim 2, characterized in that: The thiol organic compounds are one or more of 1,4-benzenedithiol (BDT), biphenyl-4,4'-dithiol, 1,4-benzenedimethanethiol, 1,2-benzenedithiol, 1,3-benzenedithiol, 2,5-diamino-1,4-benzenedithiol, pyridine-2,6-dithiol, ethanedithiol, propanedithiol; the carboxylic acid organic compounds are one or more of terephthalic acid, isophthalic acid, phthalic acid, 2-aminoterephthalic acid, 2,5-thiophenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, 4,4'-stilbenedicarboxylic acid, [1,1:4,1-triphenyl]-4,4'-dicarboxylic acid.

4. A method for preparing the metal-organic gel based on metal sulfide clusters according to claim 1, characterized in that: Using the sulfur-containing metal cluster ligand as a precursor, it combines with the organic ligand under the regulation of a base to form a uniform and porous sulfur cluster-based metal-organic sulfide gel.

5. The preparation method of the metal-organic gel based on metal sulfur clusters according to claim 4, characterized in that: 1) Dissolve the sulfur-containing metal cluster ligand as a precursor and the organic linker in an organic solvent and mix evenly to obtain Solution 1; 2) Add the alkali solution to the above Solution 1 and mix evenly to obtain Solution 2; 3) Let the obtained Solution 2 stand still to obtain a wet gel through a ligand exchange reaction at a corresponding temperature, and dry it to obtain the metal-organic gel of metal sulfur clusters.

6. The preparation method of the metal-organic gel based on metal sulfide clusters according to claim 5, characterized in that: In the step 1), the organic solvent is N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), dimethyl sulfoxide (DMSO), acetonitrile; the base can be an organic base or an inorganic base.

7. The preparation method of the metal-organic gel based on metal sulfide clusters according to claim 5, characterized in that: In the step 3), let the obtained Solution 2 stand still to obtain a wet gel through a ligand exchange reaction at 0 - 120 °C for 0.15 - 48 hours, and dry it to obtain the metal-organic gel of metal sulfur clusters.

8. The preparation method of the metal-organic gel based on metal sulfide clusters according to claim 7, characterized in that: After formation, perform solvent replacement until the original solvent is completely replaced to prepare for subsequent supercritical carbon dioxide drying.

9. The preparation method of the metal-organic gel based on metal sulfide clusters according to claim 8, characterized in that: The solvent system used in the solvent replacement method is to alternately treat with absolute ethanol and ethanol aqueous solution.

10. Use of the metal-organic gel based on metal sulfide clusters according to claim 1, characterized in that: The application of the organic gel in iodine vapor adsorption.

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