Heteroatom-containing stable mixed valence metal organic framework material as well as preparation method and application thereof

Abstract

The invention discloses a heteroatom-containing stable mixed valence metal organic framework material and a preparation method and application thereof. The stable Fe2M-PSez mixed valence metal organic framework material is formed by coordination of an organic ligand which is formed by combining phenoselenazine, phenotellurazine and isophthalic acid and a trinuclear metal cluster Fe2M. The photocatalyst has excellent water stability, chemical stability and photocatalytic activity, and can perform photocatalytic degradation while adsorbing dye molecules such as methylene blue; the material can be rapidly synthesized through a hydrothermal method, so that the material is an excellent material for photocatalytic degradation of dye molecules.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal organic framework functional materials, and in particular relates to a stable mixed-valence metal organic framework material containing heteroatoms, and a preparation method and application thereof. Background Art

[0002] Synthetic dyes have been widely used in various industries, but they are also an environmental pollutant. Once overused, industrial wastewater containing synthetic dyes will be discharged into the surrounding water uncontrollably, causing over-nutrientization of the water body, reducing the oxidation capacity of aquatic organisms, and causing serious damage to aquatic plants and animals. At the same time, with the use of aquatic food by humans, the bioaccumulation and biomagnification of these toxic dyes in the aquatic environment also indirectly affect human health.

[0003] Methylene blue (MB) is a well-known and highly carcinogenic thiazine pollutant that has been used in many industries for different purposes. MB is known to cause damage to the nervous system and eyes and poses a serious threat to human health if ingested. Therefore, it is imperative to develop advanced strategies to eliminate such harmful pollutants from water bodies.

[0004] There are many methods in the prior art to effectively degrade / remove harmful pollutants from water media; among them, adsorption and catalytic degradation are the most widely reported methods for dye removal. Among the adsorption methods, activated carbon is considered to be the most promising adsorbent, but activated carbon is obtained by calcination in a high-temperature, oxygen-free environment, and its production cost is relatively high and the manufacturing process is relatively complex. Photocatalytic removal of pollutants in catalytic degradation has advantages over other catalytic degradations, including the use of renewable resources (sunlight), simple operation scheme, effective removal and complete mineralization of dyes, etc.; it is considered to be a green, efficient and economical degradation pathway. However, most of the photocatalysts currently used are water-unstable and their structures are easily destroyed; or they require the use of precious metals and the formation of heterojunctions, which leads to increased costs or complex structures. Summary of the invention

[0005] Based on the above reasons, the first object of the present invention is to provide a stable mixed-valence metal organic framework material containing heteroatoms, which has a regular appearance and high chemical stability and water stability; the larger conjugated structure of the ligand has a wide absorption of visible light and promotes the catalytic oxidation activity of the metal cluster.

[0006] The second purpose of the present invention is to provide a method for preparing a heteroatom-based stable mixed-valence metal organic framework material, which is rapidly synthesized by a hydrothermal method and is simple.

[0007] The third object of the present invention is to provide a stable mixed-valence metal organic framework material containing heteroatoms for use as a photocatalytic reaction catalyst in the photocatalytic degradation of methylene blue.

[0008] The first object of the present invention can be achieved by adopting the following technical solutions:

[0009] A stable mixed-valence metal organic framework material containing heteroatoms, wherein an organic ligand having a structure shown in formula I coordinates with a Fe2M metal cluster to form a mixed-valence metal organic framework material; M in the Fe2M metal cluster is one of Ni, Mn or Co; R in the organic ligand having a structure shown in formula I is Se or Te;

[0010] The two carboxyl groups of each organic ligand are respectively connected to different Fe2M metal clusters; the two acetic acid coordination groups between two Fe atoms on each Fe2M metal cluster are replaced by the carboxyl groups of the ligand; one of the two acetic acid coordination groups between the Fe atom and the M metal is replaced by the carboxyl group of the ligand;

[0011]

[0012] The second object of the present invention can be achieved by adopting the following technical solutions:

[0013] A method for preparing a stable mixed-valence metal organic framework material containing heteroatoms comprises the steps of subjecting an organic ligand having a structure shown in formula I and a Fe2M metal cluster to a solvothermal reaction in an organic solvent under the catalysis of acetic acid to prepare the stable mixed-valence metal organic framework material containing heteroatoms.

[0014] Furthermore, the mass ratio of the organic ligand to the Fe2M metal cluster is 1:(1-1.2).

[0015] Furthermore, the organic solvent is DMF or DEF or a mixture of both.

[0016] Furthermore, the volume ratio of acetic acid to the organic solvent is 1:(1-20).

[0017] Furthermore, the mass volume ratio of the organic ligand to the total volume of acetic acid and the organic solvent is 1: (0.15-0.8) mg / ml.

[0018] Furthermore, the solvent thermal reaction conditions are: reaction at 110-165° C. for 12-72 h.

[0019] Furthermore, the preparation route of the organic ligand of the structure shown in Formula I is:

[0020]

[0021] Wherein R is Se or Te.

[0022] Further, when R is Se, the preparation method of the compound of the structure shown in Formula II is:

[0023]

[0024] The compound of the structure shown in formula III is reacted with Se, SeO2 and I2 in the presence of diphenylamine in a sulfolane solvent under reflux reaction to prepare the compound of the structure shown in formula II.

[0025] Further, when R is Te, the preparation method of the compound of the structure shown in formula II is:

[0026]

[0027] 2-bromoaniline and 2-bromoiodobenzene are subjected to palladium-catalyzed CN coupling to prepare a compound of formula IV; the compound of formula IV is reacted with an iodine source under the catalysis of cuprous iodide to prepare a compound of formula V; the compound of formula V is cyclized with Te under alkaline conditions to prepare a compound of formula II.

[0028] Furthermore, the temperature is lowered after the dissolution heat reaction, and the temperature is lowered to 15-35° C. under natural conditions.

[0029] Furthermore, after cooling, the method further comprises: performing solid-liquid separation on the system obtained after cooling, and then washing and drying the obtained solid matter in sequence to obtain a stable mixed-valence metal organic framework material containing heteroatoms.

[0030] Furthermore, the washing reagents are N,N-dimethylformamide and ethanol.

[0031] Furthermore, the drying is air-drying under natural conditions.

[0032] The third object of the present invention can be achieved by adopting the following technical solutions:

[0033] The heteroatom-containing stable mixed-valence metal organic framework material is used as a photocatalytic reaction catalyst in the photocatalytic degradation of methylene blue.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The present invention discloses a stable mixed-valence metal organic framework material containing heteroatoms. The heteroatom-containing MOF is constructed by connecting pheneselenazine or phentellurizine with isophthalic acid as a monomer and using a trinuclear metal cluster Fe2M as a metal connection site. Phenoselenazine or phentellurizine and the benzene ring provide a larger conjugated structure with wide absorption of visible light, which promotes the photocatalytic activity of MOF. The connection between the trinuclear metal cluster Fe2M and multiple ligands makes the MOF structure more stable, forms a regular appearance, and increases the chemical stability and water stability of the catalyst.

[0036] 2. The preparation method of the heteroatom-containing stable mixed-valence metal organic framework material of the present invention can be prepared by solvent thermal reaction; the preparation process is simple and can be easily prepared on a large scale.

[0037] 3. The application of the heteroatom-containing stable mixed-valence metal organic framework material of the present invention as a photocatalytic reaction catalyst in the photocatalytic degradation of methylene blue. The inherent porous structure of MOF has an adsorption effect on methylene blue, which is more conducive to the degradation of methylene blue by MOF. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the H NMR spectrum of pheneselenazine prepared in Example 1;

[0039] Figure 2 This is the H NMR spectrum of PSez-2COOCH3 prepared in Example 2;

[0040] Figure 3 This is the H NMR spectrum of H2PSez prepared in Example 3;

[0041] Figure 4 This is the H NMR spectrum of bis(2-bromophenyl) prepared in Example 4;

[0042] Figure 5 This is the H NMR spectrum of bis(2-iodophenyl) prepared in Example 5;

[0043] Figure 6 This is the H NMR spectrum of phentellurizine prepared in Example 6;

[0044] Figure 7 This is the H NMR spectrum of PTez-2COOCH3 prepared in Example 7;

[0045] Figure 8 This is the H NMR spectrum of H2PTez prepared in Example 8;

[0046] Fig. 9 The SEM image and element distribution diagram of Fe2Ni-PSez prepared in Example 9;

[0047] Fig.10 X-ray powder diffraction patterns of Fe2Ni-PSez, Fe2Co-PSez and Fe2Mn-PSez prepared in Examples;

[0048] Fig.11 Fourier transform-infrared spectra of organic ligand H2PSez, Fe2Ni-PSez, Fe2Co-PSez and Fe2Mn-PSez prepared in the examples;

[0049] Fig.12is the thermogravimetric analysis diagram of Fe2Ni-PSez prepared in Example 9 under nitrogen conditions;

[0050] Fig.13 The X-ray powder diffraction patterns of Fe2Ni-PSez after being immersed in different solvents for 24 hours;

[0051] Fig.14 This is the standard curve of methylene blue solution;

[0052] Fig.15 Quantitative UV-vis graphs for the performance of Fe2M-PSez;

[0053] Fig.16 The comparison of methylene blue absorbance when Fe2M-PSez is degraded by methylene blue with or without light exposure;

[0054] Fig.17 This is a bar graph of the degradation of methylene blue by Fe2Ni-PSez under different scavengers;

[0055] Fig.18 This is the molecular structure diagram of Fe2Ni-PSez prepared in Example 9. DETAILED DESCRIPTION

[0056] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only partial embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0057] In the current photocatalytic technology, the stability of the photocatalyst is a big challenge; most of the photocatalysts used are unstable in water and their structures are easily destroyed; or the materials are hydrophobic and it is difficult to play a good role in the water medium. Therefore, it is difficult to reuse the photocatalyst multiple times or achieve good photocatalytic degradation performance. In view of this, the present invention provides a stable mixed-valence metal organic framework material containing heteroatoms and its preparation method and application.

[0058] A stable mixed-valence metal organic framework material containing heteroatoms, wherein an organic ligand having a structure shown in formula I coordinates with a Fe2M metal cluster to form a mixed-valence metal organic framework material; M in the Fe2M metal cluster is one of Ni, Mn or Co; R in the organic ligand having a structure shown in formula I is Se or Te;

[0059] The two carboxyl groups of each organic ligand are respectively connected to different Fe2M metal clusters; the two acetic acid coordination groups between two Fe atoms on each Fe2M metal cluster are replaced by the carboxyl groups of the ligand; one of the two acetic acid coordination groups between the Fe atom and the M metal is replaced by the carboxyl group of the ligand;

[0060]

[0061] The invention discloses a stable mixed-valence metal organic framework material containing heteroatoms, wherein the ligand is composed of phenoselenazine or phentellurizine and isophthalic acid, wherein the carboxyl group is used as a group connected to the metal cluster, and the benzene ring and phenoselenazine or phentellurizine provide a larger conjugated structure, which has a wide absorption of visible light and can effectively absorb light energy, promote the occurrence of photocatalytic reactions, and improve photocatalytic performance. The metal cluster is used as a stable structure and is connected with multiple ligands to form a MOF, and the obtained MOF has a regular appearance and a stable structure, and therefore has excellent chemical stability and water stability.

[0062] The present invention also provides a method for preparing a stable mixed-valence metal organic framework material containing heteroatoms, comprising subjecting an organic ligand having a structure shown in Formula I and a Fe2M metal cluster to a solvothermal reaction in an organic solvent under the catalysis of acetic acid to prepare the stable mixed-valence metal organic framework material containing heteroatoms.

[0063] As one embodiment, the mass ratio of the organic ligand to the Fe2M metal cluster is 1:(1-1.2).

[0064] As one embodiment, the organic solvent is DMF or DEF or a mixture of both.

[0065] As one embodiment thereof, the volume ratio of acetic acid to the organic solvent is 1:(1-20).

[0066] As one embodiment, the mass volume ratio of the organic ligand to the total volume of acetic acid and the organic solvent is 1: (0.15-0.8) mg / ml.

[0067] As one embodiment, the solvent thermal reaction conditions are: reaction at 110-165° C. for 12-72 hours.

[0068] The material ratio and reaction conditions of the reaction can be adjusted according to the solvent thermal reaction, but under the above reaction conditions, a stable mixed-valence metal organic framework material containing heteroatoms can be obtained.

[0069] As one embodiment, the temperature is lowered after the dissolution heat reaction, and the temperature is lowered to 15-35° C. under natural conditions.

[0070] As one embodiment, after cooling, the method further comprises: performing solid-liquid separation on the system obtained after cooling, and then washing and drying the obtained solid matter in sequence to obtain a stable mixed-valence metal organic framework material containing heteroatoms.

[0071] As one embodiment, the washing reagents are N,N-dimethylformamide and ethanol.

[0072] As one embodiment, the drying is air-drying under natural conditions.

[0073] As one embodiment, the preparation route of the organic ligand with the structure shown in Formula I is:

[0074]

[0075] Wherein R is Se or Te.

[0076] In this embodiment, phenoselenazine or phentellurizine is subjected to a coupling reaction with dimethyl iodoisophthalate under the catalysis of zero-valent palladium.

[0077] As one embodiment, the coupling reaction system is: the catalyst is 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl and tris(dibenzylideneacetone)dipalladium(0); cesium carbonate is the base; toluene is the solvent; in an inert gas atmosphere; the reaction is carried out at 100-120° C. for 24-72 hours.

[0078] The coupling product is hydrolyzed and acidified in an ethanol solution under alkaline conditions to obtain an organic ligand with a structure shown in formula I.

[0079] As one embodiment, when R is Se, the preparation method of the compound of the structure shown in Formula II is:

[0080]

[0081] The compound of the structure shown in formula III is reacted with Se, SeO2 and I2 in the presence of diphenylamine in a sulfolane solvent under reflux reaction to prepare the compound of the structure shown in formula II.

[0082] As one embodiment, when R is Te, the preparation method of the compound of the structure shown in formula II is:

[0083]

[0084] 2-bromoaniline and 2-bromoiodobenzene are subjected to palladium-catalyzed CN coupling to prepare a compound of formula IV; the compound of formula IV is reacted with an iodine source under the catalysis of cuprous iodide to prepare a compound of formula V; the compound of formula V is cyclized with Te under alkaline conditions to prepare a compound of formula II.

[0085] In this embodiment, a catalytic CN coupling reaction is carried out, wherein the palladium catalyst is tris(dibenzylideneacetone)dipalladium and 1,1'-bis(diphenylphosphino)ferrocenepalladium dichloride, sodium tert-butoxide is used as a base, toluene is used as a solvent, and the reaction is carried out at 110-130° C. for 10-36 hours under an inert gas atmosphere.

[0086] In this embodiment, in preparing the compound of the structure shown in formula V, the iodine source is NaI; N-N'-dimethylethylenediamine is the base; 1,4-dioxane is the solvent, and the reaction is carried out at 100-120°C for 12-36 hours under an inert gas atmosphere.

[0087] In this embodiment, in preparing the compound of formula II, the compound of formula V, Te element and alkali potassium hydroxide are dissolved in DMSO and reacted at 100-120° C. for 12-36 hours under an inert gas atmosphere.

[0088] The present invention also provides a use of a stable mixed-valence metal organic framework material containing heteroatoms as a photocatalytic reaction catalyst in photocatalytic degradation of methylene blue.

[0089] Stable mixed-valence metal-organic framework materials containing heteroatoms are used as photocatalytic reaction catalysts to photodegrade methylene blue in aqueous solution under light conditions.

[0090] The following is a further description with reference to specific embodiments.

[0091] Example 1

[0092]

[0093] Prepare a 50mL reaction flask, weigh 400mg of diphenylamine, 93mg of Se, 160mg of SeO2, 30mg of I2, and 10mL of sulfolane, add them into the reaction flask under nitrogen atmosphere, and reflux and stir at 150°C for 12h; after the reaction mixture is cooled to room temperature, pour the mixture into 50mL of water and extract with ethyl acetate (3×50mL); then wash the combined organic layer with water (3×50mL), dry with anhydrous sodium sulfate, and remove the organic solvent with a rotary evaporator; the residue is further purified by column chromatography (silica gel, using petroleum ether and ethyl acetate as eluents) to obtain 350mg of pheneselenazine with a yield of 60%; named PSez; H NMR spectrum as shown Figure 1 As shown;

[0094] 1 H NMR (400MHz, DMSO) δ8.58 (s, 1H), 7.14-7.06 (m, 2H), 7.02 (td, J = 7.5, 1.5Hz, 2H), 6.80-6.72 (m, 4H).

[0095] Example 2

[0096]

[0097] S1 (200 mg, 0.812 mmol), dimethyl 5-iodoisophthalate (312 mg, 0.974 mmol), cesium carbonate (662 mg, 2 mmol), 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl (19.4 mg, 0.4 mmol) and tris(dibenzylideneacetone)dipalladium (22.3 mg, 0.2 mmol) were added to a 100 mL reaction flask, which was then evacuated and refilled with N2 three times; 20 mL of toluene solvent was degassed and injected into the reaction flask through a cannula under N2; the reaction flask was then connected to a condenser and refluxed at 110°C for 3 d under N2 protection; after the reaction mixture was cooled to room temperature, the mixture was poured into 50 mL of water and extracted with ethyl acetate (3×50 mL). The combined organic layer was then washed with water (3×50 mL), dried over anhydrous sodium sulfate, and the organic solvent was removed by a rotary evaporator; the residue was further purified by column chromatography (silica gel, using petroleum ether and ethyl acetate as eluents) to obtain 320 mg of the structural compound represented by formula VI, with a yield of 90% based on pheneselenazine, named PSez-2COOCH3; the H NMR spectrum was as follows Figure 2 As shown;

[0098] 1 H NMR (400MHz, DMSO) δ8.03 (t, J=1.4Hz, 1H), 7.75 (dd, J=7.7, 1.4Hz, 2H), 7.63 (d, J=1.4Hz,2H),7.52-7.44(m,4H),7.30(ddd,J=7.7,6.9,1.8Hz,2H),3,81(s,6H).

[0099] Example 3

[0100]

[0101] The compound of formula VI (500 mg, 1.140 mmol) was dissolved in 16 mL of EtOH, and 8 mL of 2M NaOH aqueous solution was added, and the mixture was reacted at 75°C for 4 h. After cooling to room temperature, the organic solvent was removed by a rotary evaporator, 50 mL of water was added, and the reaction mixture was acidified with concentrated HCl. The precipitate was collected by filtration and washed with water to obtain 397 mg of an organic ligand of formula I with a yield of 85%, named H2PSez, and the H NMR spectrum was as follows: Figure 3 As shown;

[0102] 1H NMR (400MHz, DMSO) δ13.22 (s, 2H), 8.04-8.02 (m, 1H), 7.75-7.70 (m, 2H), 7.62 (d, J = 1.4Hz, 2H), 7.48-7.42 (m, 4H), 7.28 (ddd, J = 8.6, 6.2, 2.6Hz, 2H).

[0103] Example 4

[0104]

[0105] In a 50 mL reaction flask, 200 mg of 2-bromoaniline, 395 mg of 2-bromoiodobenzene, 160 mg of sodium tert-butoxide, 54 mg of tris(dibenzylideneacetone)dipalladium and 85 mg of 1,1'-bis(diphenylphosphinoferrocene)palladium dichloride were weighed, 10 mL of toluene solvent was degassed, and injected into the reaction flask through a cannula under N2; the reaction flask was then connected to a condenser and refluxed at 120 °C for 18 h under N2 protection; after the reaction mixture was cooled to room temperature, the mixture was poured into 50 mL of water and extracted with ethyl acetate (3 × 50 mL); the combined organic layer was then washed with water (3 × 50 mL), dried over anhydrous sodium sulfate, and the organic solvent was removed by a rotary evaporator. The residue was further purified by column chromatography (silica gel, with petroleum ether as the eluent) to obtain 260 mg of bis(2-bromophenyl)amine with a yield of 70%, and the H NMR spectrum was as follows Figure 4 As shown;

[0106] 1 H NMR (400MHz, DMSO) δ7.61 (dd, J = 8.0, 1.5 Hz, 2H), 7.27 (ddd, J = 8.6, 7.4, 1.5 Hz, 2H), 7.06 (dd, J = 8.1, 1.6 Hz, 2H), 6.97 (s, 1H), 6.91 (td, J = 7.6, 1.6 Hz, 2H).

[0107] Example 5

[0108]

[0109] In a 50 mL reaction flask, weigh 200 mg of bis(2-bromophenyl)amine, 12 mg of CuI, 367 mg of NaI, and 10.7 mg of N-N'-dimethylethylenediamine. Degas 5 mL of ultra-dry 1,4-dioxane solvent and inject it into the reaction flask through a cannula under N2; stir at 110 °C for 24 h under N2 protection; after the reaction mixture is cooled to room temperature, pour the mixture into 25% ammonia solution (10 mL) and water (50 mL) and extract with ethyl acetate (3×50 mL). The combined organic layer is then washed with water (3×50 mL), dried over anhydrous sodium sulfate, and the organic solvent is removed by a rotary evaporator. The residue is further purified by column chromatography (silica gel, using petroleum ether as eluent) to obtain 200 mg of bis(2-iodophenyl)amine, with a yield of 80% based on bis(2-bromophenyl)amine, and the nuclear magnetic hydrogen spectrum is as follows Figure 5 As shown;

[0110] 1 H NMR (400MHz, DMSO) δ7.85 (dd, J = 7.8, 1.5 Hz, 2H), 7.29 (ddd, J = 8.5, 7.3, 1.5 Hz, 2H), 6.99 (dd, J = 8.1, 1.5 Hz, 2H), 6.77 (td, J = 7.5, 1.5 Hz, 2H), 6.63 (s, 1H).

[0111] Example 6

[0112]

[0113] In a 50 mL reaction flask, 200 mg of bis(2-iodophenyl)amine, 120 mg of Te and 106 mg of KOH were weighed, 5 mL of DMSO solvent was degassed and injected into the reaction flask through a cannula under N2; the mixture was stirred at 110°C for 24 h under N2 protection; after the reaction mixture was cooled to room temperature, the mixture was poured into 10 mL of 25% NH4Cl solution and 50 mL of water and extracted with ethyl acetate (3×50 mL); the combined organic layer was then washed with water (3×50 mL), dried over anhydrous sodium sulfate, and the organic solvent was removed by a rotary evaporator; the residue was further purified by column chromatography (silica gel, with petroleum ether and ethyl acetate as eluents) to obtain 85 mg of phentellurizine, with a yield of 60% based on bis(2-iodophenyl)amine, and the H NMR spectrum was as follows: Figure 6 As shown;

[0114] 1H NMR (400MHz, DMSO) δ8.52 (s, 1H), 7.32 (dd, J = 7.5, 1.5 Hz, 2H), 7.03 (ddd, J = 8.0, 7.3, 1.6 Hz, 2H), 6.87 (dd, J = 8.1, 1.3 Hz, 2H), 6.74 (td, J = 7.4, 1.3 Hz, 2H).

[0115] Example 7

[0116]

[0117] Phenyltellurizine (200 mg, 0.678 mmol), dimethyl 5-iodoisophthalate (260 mg, 0.812 mmol), cesium carbonate (520 mg, 1.60 mmol), 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl (16.2 mg, 0.033 mmol) and tris(dibenzylideneacetone)dipalladium (18.7 mg, 0.02 mmol) were added to a 100 mL reaction flask, which was then evacuated and refilled with N2 three times; 20 mL of toluene solvent was degassed and injected through a cannula under N2. The reaction flask was then connected to a condenser and refluxed at 110°C for 3 days under N2 protection; after the reaction mixture was cooled to room temperature, the mixture was poured into 50 mL of water and extracted with ethyl acetate (3×50 mL); the combined organic layer was then washed with water (3×50 mL), dried over anhydrous sodium sulfate, and the organic solvent was removed by a rotary evaporator; the residue was further purified by column chromatography (silica gel, using petroleum ether and ethyl acetate as eluents) to obtain 280 mg of the compound of structure VI, with a yield of 85% based on phentellurizine, and the H NMR spectrum was as follows Figure 7 As shown;

[0118] 1 H NMR (400MHz, DMSO) δ8.09(t,J=1.4Hz,1H),7.85(dd,J=7.6,1.5Hz,2H),7.63(dd,J=7.9,1.3Hz,2 H), 7.58 (d, J = 1.4Hz, 2H), 7.44 (td, J = 7.6, 1.5Hz, 2H), 7.19 (td, J = 7.5, 1.4Hz, 2H), 3.84 (s, 6H).

[0119] Example 8

[0120]

[0121] The compound of formula VI (500 mg, 1.089 mmol) was dissolved in 16 mL of EtOH, and 8 mL of 2M NaOH aqueous solution was added, and the mixture was reacted at 75°C for 4 h. After cooling to room temperature, the organic solvent was removed by a rotary evaporator, 50 mL of water was added, and the reaction mixture was acidified with concentrated HCl. The precipitate was collected by filtration and washed with water to obtain 400 mg of an organic ligand of formula I with a yield of 85%, named H2PTez, and the H NMR spectrum was as follows: Figure 8 As shown;

[0122] 1 H NMR (400MHz, DMSO) δ13.08(s,2H),7.98(dd,J=7.7,1.5Hz,2H),7.86(t,J=1.4Hz,1H),7.68(dd,J =7.9, 1.3Hz, 2H), 7.50 (td, J = 7.6, 1.5Hz, 2H), 7.37 (d, J = 1.4Hz, 2H), 7.25 (td, J = 7.5, 1.3Hz, 2H).

[0123] Example 9

[0124] 2 mg of ligand H2PSez and 2 mg of Fe2Ni metal cluster were added to a glass tube, and 50 μL of acetic acid and 0.5 mL of DMF were added in sequence; the glass tube was sealed by a hydrogen generator; the glass tube was placed in an ultrasonic bath and ultrasonicated for 10 min; the glass tube was placed in an oven and heated at 140°C for 48 h; after cooling to room temperature, the glass tube was opened, the solid product was collected by centrifugation, and the solid product was washed three times with N, N-dimethylformamide and ethanol in sequence; the product was obtained after drying, and its appearance was as follows Fig. 9 As shown, it is named Fe2Ni-PSez; the molecular structure is as follows Fig.18 shown.

[0125] Example 10

[0126] 2 mg of ligand H2PSez and 2.4 mg of Fe2Co metal cluster were added into a glass tube, and then 0.8 mL of acetic acid, 0.4 mL of DMF and 0.4 mL of DEF were added in sequence; the glass tube was sealed by a hydrogen generator; the glass tube was placed in an ultrasonic bath and treated with ultrasound for 10 min; the glass tube was placed in an oven and heated at 125 °C for 60 h; after cooling to room temperature, the glass tube was opened, the solid product was collected by centrifugation, and the solid product was washed twice with N, N-dimethylformamide and ethanol in sequence; the product was obtained after drying, and was named Fe2Co-PSez.

[0127] Embodiment 11

[0128] 2 mg of ligand H2PSez and 2.1 mg of Fe2Mn metal cluster were added to a glass tube, and 100 μL of acetic acid and 1 mL of DEF were added in turn; the glass tube was sealed by a hydrogen and oxygen machine; the glass tube was placed in an ultrasonic bath and treated with ultrasound for 10 min; the glass tube was placed in an oven and heated at 165 °C for 24 h; after cooling to room temperature, the glass tube was opened, the solid product was collected by centrifugation, and the solid product was washed four times with N, N-dimethylformamide and ethanol in turn; the product was obtained after drying and named Fe2Mn-PSez.

[0129] Example 12

[0130] 2 mg of ligand H2PTez and 2.3 mg of Fe2Ni metal cluster were added into a glass tube, and then 50 μL of acetic acid and 0.25 mL of DMF were added in sequence; the glass tube was sealed by a hydrogen generator; the glass tube was placed in an ultrasonic bath and treated with ultrasound for 10 min; the glass tube was placed in an oven and heated at 110 °C for 72 h; after cooling to room temperature, the glass tube was opened, the solid product was collected by centrifugation, and the solid product was washed three times with N, N-dimethylformamide and ethanol in sequence; the product was obtained after drying and named Fe2Ni-PTez.

[0131] Test example:

[0132] (1) X-ray powder diffraction test was performed on Fe2Ni-PSez, Fe2Co-PSez and Fe2Mn-PSez prepared in Example; the results are as follows: Fig.10 shown.

[0133] From the results of X-ray powder diffraction test, it can be seen that the synthetic Fe2M-PSez diffraction spectrum is highly consistent with the simulated diffraction spectrum in peak position, indicating that the synthesized Fe2M-PSez is pure phase and the three different metal clusters have the same main framework. It can also be seen from the diffraction spectrum that the diffraction peak of Fe2M-PSez is very strong and sharp, indicating that the synthesized MOF has good crystallinity.

[0134] (2) The organic ligand H2PSez, Fe2Ni-PSez, Fe2Co-PSez and Fe2Mn-PSez prepared in the examples were detected by Fourier transform-infrared spectroscopy. The results are as follows Fig.11 shown.

[0135] It is clearly observed from the infrared spectrum that the ligand H2PSez at 2576 cm -1 and 2515cm -1 The characteristic peak of carboxylic acid disappears, and the characteristic peak of carbonyl in ligand H2PSez decreases from 1688 cm -1 Offset to 1629cm -1, indicating that the carboxylic acid functional groups in the ligands coordinate with the metal clusters. The stretching vibration peaks of the metal clusters can still be seen in the fingerprint regions of Fe2Ni-PSez, Fe2Co-PSez and Fe2Mn-PSez, indicating that the metal clusters are well preserved during the synthesis process and that the carboxylic acid functional groups in the ligands coordinate with the metal clusters to form the main framework.

[0136] (3) The Fe2Ni-PSez prepared in Example 9 was observed by scanning electron microscope (SEM). Fig. 9 As shown in the left figure; the element distribution is as follows Fig. 9 As shown in the picture on the right.

[0137] from Fig. 9 From the SEM image, we can see that the stable mixed-valence metal-organic framework material containing heteroatoms has a polyhedral structure with a relatively regular morphology; and from the element distribution, we can see that the elements are evenly distributed.

[0138] (4) Thermogravimetric analysis of Fe2Ni-PSez was performed under nitrogen conditions. The results are as follows Fig.12 shown.

[0139] Under nitrogen conditions, Fe2Ni-PSez maintains structural stability within 306℃, and the mass balance loss before 306℃ is negligible, indicating that it has good thermal stability.

[0140] (5) 5 mg of the heteroatom-containing stable mixed-valence metal organic framework material Fe2Ni-PSez prepared in Example 9 was soaked in 5 mL of different solvents and aqueous solutions of different pH values, and then centrifuged after soaking for 24 h. After vacuum drying at 45° C., an X-ray powder diffraction test was performed. The test results are as follows: Fig.13 shown.

[0141] from Fig.13 It can be seen that after immersion in air, DMF, ethanol, water, acetonitrile, methanol, and acetone for 24 hours, and in an aqueous solution with a pH of 1-11 for 24 hours, the XRD peak of the heteroatom-containing stable mixed-valence metal-organic framework material Fe2Ni-PSez of the present invention does not change basically, indicating that the MOF framework does not change basically, indicating good chemical stability and water stability.

[0142] Test example:

[0143] Weigh 10 mg of Fe2Co-PSez and Fe2Ni-PSez respectively and add them into the photocatalytic reaction bottle, add 10 mL of 10 mg / L methylene blue solution, stir for 30 min in the dark to reach adsorption equilibrium, and then irradiate with xenon light for 4 h; the methylene blue concentration is detected by measuring the absorbance of the solution after the reaction; at the same time, a control experiment is performed in the dark without xenon light for 4 h; the standard curve of methylene blue solution is shown in the figure below: Fig.14 As shown; the absorbance curve of methylene blue solution after 4h treatment with light and without light is as shown Figure 15-16 shown.

[0144] from Figure 15-16 It can be seen that after 4 h of illumination, Fe2Co-PSez degraded 10 mg / L methylene blue solution to 4.84 mg / L, with a degradation degree of 51.6%; Fe2Ni-PSez degraded 10 mg / L methylene blue solution to 4.12 mg / L, with a degradation degree of 58.8%.

[0145] At this time, after 4 hours of reaction in the dark, Fe2Co-PSez degraded 10mg / L methylene blue solution to 6.72mg / L, with a degradation rate of 32.8%; Fe2Ni-PSez degraded 10mg / L methylene blue solution to 5.97mg / L, with a degradation rate of 40.3%. It can be seen that Fe2Ni-PSez is better than Fe2Co-PSez in degrading methylene blue, and under the condition of xenon lamp, the performance of Fe2M-PSez MOF is better than that in the dark, indicating its photocatalytic activity.

[0146] Furthermore, using Fe2Ni-PSez as a catalyst, 10 mg of Fe2Ni-PSez was weighed and added to a photocatalytic reaction bottle, 10 mL of 10 mg / L methylene blue solution was added, and methanol (as a + The mixture was stirred for 30 min in the dark to reach adsorption equilibrium, and then illuminated with a xenon lamp for 4 h. The concentration of methylene blue was detected by measuring the absorbance of the solution after the reaction and the degree of degradation was calculated. The results are as follows: Fig.17 shown.

[0147] from Fig.17 It can be seen that after adding methanol and isopropanol, the degradation performance decreased, which can indicate that holes and hydroxyl radicals are involved in the photocatalytic degradation of methylene blue, and Fe2Ni-PSez is used as a catalyst to photocatalyze the degradation of methylene blue.

[0148] In summary, the present invention uses an organic ligand composed of pheneselenazine, phentellurizine and isophthalic acid to coordinate with the trinuclear metal cluster Fe2M to form a stable Fe2M-PSez MOF; the MOF has a cyclic conjugated structure containing heteroatoms, so that the MOF has good light absorption performance, and thus has excellent photocatalytic activity; at the same time, the porous structure of the MOF itself has an adsorption effect on dye molecules such as methylene blue, which can further enhance the catalytic performance of the MOF on dye molecules. In particular, the MOF prepared by the present invention has excellent water stability and chemical stability, and is rapidly synthesized by a hydrothermal method, so it is a class of excellent materials for photocatalytic degradation of dye molecules.

[0149] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A stable mixed-valence metal organic framework material containing heteroatoms, characterized in that: The organic ligand of the structure shown in Formula I coordinates with the Fe2M metal cluster to form a mixed-valence metal organic framework material; M in the Fe2M metal cluster is one of Ni, Mn or Co; R in the organic ligand of the structure shown in Formula I is Se or Te; The two carboxyl groups of each organic ligand are respectively connected to different Fe2M metal clusters; the two acetic acid coordination groups between two Fe atoms on each Fe2M metal cluster are replaced by the carboxyl groups of the ligand; one of the two acetic acid coordination groups between the Fe atom and the M metal is replaced by the carboxyl group of the ligand; 2. A method for preparing a stable mixed-valence metal organic framework material containing heteroatoms according to claim 1, characterized in that: The organic ligand with the structure shown in formula I and the Fe2M metal cluster are subjected to a solvothermal reaction in an organic solvent under the catalysis of acetic acid to prepare the stable mixed-valence metal organic framework material containing heteroatoms.

3. The method for preparing a stable mixed-valence metal organic framework material containing heteroatoms according to claim 2, characterized in that: The mass ratio of organic ligand to Fe2M metal cluster is 1:(1-1.2).

4. The method for preparing a stable mixed-valence metal organic framework material containing heteroatoms according to claim 2, characterized in that: The organic solvent is one of DMF or DEF or a mixture of the two; the volume ratio of acetic acid to the organic solvent is 1:(1-20); the mass volume ratio of the organic ligand to the total volume of acetic acid and the organic solvent is 1:(0.15-0.8) mg / ml.

5. The method for preparing a stable mixed-valence metal organic framework material containing heteroatoms according to claim 2, characterized in that: The conditions of the solvent thermal reaction are reaction at 110-165°C for 12-72h.

6. The method for preparing a stable mixed-valence metal organic framework material containing heteroatoms according to claim 2, characterized in that: The preparation route of the organic ligand of the structure shown in Formula I is: Wherein R is Se or Te.

7. The method for preparing a stable mixed-valence metal organic framework material containing heteroatoms according to claim 6, characterized in that: When R is Se, the preparation method of the compound of the structure shown in formula II is: The compound of the structure shown in formula III is reacted with Se, SeO2 and I2 in the presence of diphenylamine in a sulfolane solvent under reflux reaction to prepare the compound of the structure shown in formula II.

8. The method for preparing a stable mixed-valence metal organic framework material containing heteroatoms according to claim 6, characterized in that: When R is Te, the preparation method of the compound of the structure shown in formula II is: 2-bromoaniline and 2-bromoiodobenzene are subjected to palladium-catalyzed CN coupling to prepare a compound of formula IV; the compound of formula IV is reacted with an iodine source under the catalysis of cuprous iodide to prepare a compound of formula V; the compound of formula V is cyclized with Te under alkaline conditions to prepare a compound of formula II.

9. The method for preparing a stable mixed-valence metal organic framework material containing heteroatoms according to any one of claims 2 to 8, characterized in that: After the dissolution heat reaction, the temperature is lowered to 15-35°C under natural conditions; after the cooling, the system obtained after the cooling is subjected to solid-liquid separation, and then the obtained solid matter is washed and dried in sequence to obtain a stable mixed-valence metal organic framework material containing heteroatoms; the washing reagents used are N, N-dimethylformamide and ethanol; and the drying is air-drying under natural conditions.

10. Use of the heteroatom-containing stable mixed-valence metal organic framework material according to any one of claims 1 to 9 as a photocatalytic reaction catalyst in photocatalytic degradation of methylene blue.

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