Preparation method and application of thienyl metal organic framework material

Abstract

The invention discloses a preparation method and application of a thienyl metal organic framework material, a 1, 2, 4, 5-tetra (5-bromothiophene) benzene intermediate is synthesized through a Steyler reaction and an NBS bromination reaction, the intermediate reacts with 4-methoxycarbonyl phenylboronic acid to obtain long-size 1, 2, 4, 5-tetra (2-(5-(4-carboxyphenyl)) thienyl) benzene with a large conjugated system, and the long-size 1, 2, 4, 5-tetra (2-(5-(4-carboxyphenyl)) thienyl) benzene has a large conjugated system. And self-assembling with Zr < 4 + > by adopting a solvothermal method to obtain the MOF with a stable structure and an excellent fluorescent property. The prepared fluorescence-enhanced metal organic framework material has excellent chemical and hydrothermal stability, the quenching rate and recognition sensitivity of the fluorescence-enhanced metal organic framework material to Fe < 3 + > and aromatic nitro compounds are kept at 95% and above 104 orders of magnitude, and the prepared MOF has good application in selective fluorescence detection of Fe < 3 + > and aromatic nitro compounds.

Description

Technical Field

[0001] The present invention relates to the technical field of metal organic framework materials, and in particular to a preparation method and application of a thiophene-based metal organic framework material. Background Art

[0002] Heavy metal ions have a certain bioaccumulation in the environment. They can gradually accumulate in the food chain and reach high concentrations. This accumulation not only increases the toxicity of heavy metal ions to organisms, but also makes it more difficult to remove heavy metal ions through biodegradation. In addition, nitro explosives, which are widely used in mining and railway construction, release harmful substances during the explosion process, causing damage to the environment and ecology.

[0003] Metal-organic frameworks (MOFs) are multidimensional ordered frameworks formed by the self-assembly of organic ligands and metal ions or metal clusters. They combine the pore structure of inorganic materials with the functional advantages of organic materials and have attracted much attention in many fields such as recognition, adsorption, and host-guest chemistry. In particular, the development of fluorescent MOFs mainly utilizes its fluorescent properties to identify and adsorb pollutants, including heavy metal ions and aromatic nitro compounds, providing new possible solutions to the increasingly serious environmental pollution and safety and health issues.

[0004] The main structure of MOFs is constructed by connecting secondary structural units through organic ligands. Therefore, the selection of metal ions and ligands plays a critical role in the structural construction and property regulation of MOFs materials. At present, most fluorescent MOFs materials use ligands containing O and N, and there are very few ligands containing S heteroatoms, which limits their synthesis and application. In addition, the bonding mode of coordination bonds makes most MOFs less stable. How MOFs can have both functionality and stability has become an important issue.

[0005] In addition to their inherent luminescent properties, conjugated thiophene compounds can enhance the structural stability of porous materials by strengthening the π-π interaction between molecules and hydrogen bonding with certain small molecules through the lone pair of electrons of the sulfur atom on the thiophene ring. However, there are only a few reports on the organic bridging ligands used to construct MOFs using conjugated thiophene compounds. Therefore, designing new conjugated thiophene ligands as organic connecting units to construct porous materials with novel structures and functions will provide a new research paradigm for improving the stability of MOFs and expanding the application of fluorescence recognition. Summary of the invention

[0006] In view of the above problems, the purpose of the present invention is to provide a preparation method and application of a thienyl metal organic framework material, wherein a 1,2,4,5-tetrakis(5-bromothiophene)benzene intermediate is synthesized by Stiller reaction and NBS bromination reaction, and then reacted with 4-methoxycarbonylphenylboronic acid to obtain a long-sized 1,2,4,5-tetrakis(2-(5-(4-carboxyphenyl))thienyl)benzene with a large conjugated system, and then a solvent thermal method is used to react with Zr 4+ The MOF with stable structure and excellent fluorescence properties was obtained by self-assembly. The prepared MOF was used for selective fluorescence detection of Fe 3+ It has good application in aromatic nitro compounds.

[0007] A thienyl metal organic framework material, wherein the thienyl metal organic framework is a zirconium metal organic framework compound obtained by coordination of thiophene carboxylic acid ligands and metal zirconium ions;

[0008] The thiophene carboxylic acid ligand is 1,2,4,5-tetrakis(2-(5-(4-carboxyphenyl))thienyl)benzene; the structural formula is as follows:

[0009]

[0010] The crystal structure of the thienyl metal organic framework is an orthorhombic Fmmm space group, α=β=γ=90°, Z=4.

[0011] The second object of the present invention is to provide a method for preparing the above-mentioned 1,2,4,5-tetrakis(2-(5-(4-carboxyphenyl))thienyl)benzene organic ligand, comprising the following steps:

[0012] 1) 1,2,4,5-tetrabromobenzene and tributyl(2-thienyl)tin are reacted to prepare 1,2,4,5-tetra(thienyl)benzene intermediate (1) through Stiller reaction;

[0013] 2) The intermediate 1 is subjected to NBS bromination reaction to prepare 1,2,4,5-tetrakis(5-bromothiophene)benzene intermediate (2);

[0014]

[0015] 3) intermediate 2 is reacted with 4-methoxycarbonylphenylboronic acid to prepare 1,2,4,5-tetrakis(2-(5-(4-benzoic acid methyl ester))thienyl)benzene intermediate (3);

[0016] 4) Intermediate 3 is hydrolyzed under acidic conditions to obtain 1,2,4,5-tetrakis(2-(5-(4-carboxyphenyl))thienyl)benzene organic ligand (TPP);

[0017]

[0018] Furthermore, the preparation method comprises the following steps: 1) 1,2,4,5-tetrabromobenzene, PdCl 2 and triphenylphosphine are added to the reaction system, oxygen in the reaction system is removed, tributyl(2-thienyl)tin and N,N-dimethylformamide solvent are continuously added to the reaction system, the mixture is dispersed and the temperature is raised to 120-150° C. for reaction for 12-18 hours, after the reaction is completed, the mixture is cooled to room temperature, filtered and washed with n-hexane to obtain a gray-black crude product, which is purified with dichloromethane as an eluent to obtain white 1,2,4,5-tetra(thienyl)benzene (1);

[0019] 2) reacting (1) obtained in step 1), N-bromosuccinimide and tetrahydrofuran solvent in a reaction system at room temperature for 24-36 hours, removing the solvent by distillation under reduced pressure, washing with water and acetone respectively to obtain a light yellow powder 1,2,4,5-tetrakis(5-bromothienyl)benzene (2);

[0020] 3) placing (2) obtained in step 2), 4-methoxycarbonylphenylboronic acid, tetrakistriphenylphosphine palladium, potassium carbonate and 1,4-dioxane in a reaction system, 2 The reaction was carried out at 90-120°C for 48-96h under protection, and the solvent was distilled under reduced pressure and then CH 2 Cl 2 The mixture was extracted with water several times, and the solvent was evaporated and then CH 2 Cl 2 Purification with 1,2,4,5-tetrakis(2-(5-(4-benzoic acid methyl ester))thienyl)benzene (3) was obtained as a bright yellow product;

[0021] 4) placing the (3) obtained in step 3) in a reaction system containing a mixed solvent, slowly adding a 1-3M KOH solution at 50-70° C. until the solution is clear, removing the solvent and slowly adding dilute hydrochloric acid dropwise until a large amount of yellow floccules appear, filtering with suction and rinsing with water until neutral, to obtain 1,2,4,5-tetrakis(2-(5-(4-carboxyphenyl))thienyl)benzene TPP;

[0022] 5) The TPP obtained in step 4) was mixed with anhydrous ZrCl 4 , anhydrous DMF and trifluoroacetic acid are mixed in proportion, sealed and placed in an oven at 100-120° C. for 48-72 hours to obtain the thienyl metal organic framework material TPP-1.

[0023] Furthermore, in the step 1), the molar ratio of 1,2,4,5-tetrabromobenzene, PdCl2, triphenylphosphine, tributyl(2-thienyl)tin and N,N-dimethylformamide is 14:1:2:56-84:35.

[0024] Furthermore, in the step 2), the molar ratio of (1), N-bromosuccinimide and tetrahydrofuran is 1:4-6:220.

[0025] Furthermore, in the step 3), the molar ratio of (2), 4-methoxycarbonylphenylboronic acid, tetrakistriphenylphosphine palladium, potassium carbonate and 1,4-dioxane is 12:48-72:1:420:27000, CH 2 Cl 2 The volume ratio of mixing with water is 1:1.

[0026] Furthermore, in the step 4), the mass volume ratio of (3) to the mixed solvent is 1-2.5:100 g / ml, and CH 3 The volume ratio of OH and THF is 1:1.

[0027] Furthermore, in step 5), TPP, anhydrous ZrCl 4 , and trifluoroacetic acid in a molar ratio of 1-3:12:500.

[0028] The third object of the present invention is to provide a method for detecting Fe by fluorescence of the above-mentioned thiophene-based metal organic framework material. 3+ Application in.

[0029] The fourth object of the present invention is to provide the application of thienyl metal organic framework materials in the fluorescence detection of aromatic nitro compounds.

[0030] Furthermore, when the thiophene-based metal organic framework material is subjected to fluorescence detection, the thiophene-based metal organic framework material TPP-1 obtained by the reaction is dispersed in DMF, a solution containing ions and compounds to be detected is added, and the mixture is mixed evenly and then detected by fluorescence emission spectroscopy.

[0031] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0032] The beneficial effects of the present invention are:

[0033] 1. The present invention designs and synthesizes a novel 1,2,4,5-tetrakis(2-(5-(4-carboxyphenyl))thienyl)benzene organic ligand having a large conjugated system and a long ligand size through Stiller reaction and NBS bromination reaction. The prepared thienyl metal organic framework material has a novel structure, and the large conjugated bond of the ligand gives it a strong fluorescence intensity. While maintaining the inherent luminescent properties of the conjugated thiophene compound itself, the structural stability of the porous material can be enhanced, and excellent chemical and hydrothermal stability is exhibited;

[0034] 2. The preparation method of the thienyl metal organic framework fluorescent material provided by the present invention is a solvothermal method, which has the advantages of simple operation for obtaining crystalline materials, controllable structure and composition, easy reproducibility and mass production;

[0035] 3. The present invention designs a new type of conjugated thiophene ligand. The S atom has a stronger polarization ability than the C and N atoms that have been studied more in the past, which can give the porous material a strong polarization ability to Fe 3+ , Hg 2+ Recognition and adsorption selectivity of metal ions such as iodine;

[0036] 4. The present invention constructs a thiophene-based metal organic framework material with stable structure and enhanced fluorescence to 3+ The quenching rate and recognition sensitivity of aromatic nitro compounds were both maintained at 95% and 10 4 orders of magnitude, showing excellent selectivity and anti-interference ability, which is a good method for identifying Fe 3+ Aromatic nitro compounds provide an excellent new fluorescent material that can quickly detect and eliminate heavy metal ions and nitro explosives, thus providing strong technical support for environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 A three-dimensional structural diagram of the thiophene-based metal organic framework material provided by the present invention;

[0039] Figure 2 The X-ray diffraction patterns of the thienyl metal organic framework material provided by the present invention under different environmental treatments, wherein (a) is the X-ray diffraction pattern of the thienyl metal organic framework material under H 2 Powder X-ray diffraction test was performed after treatment in O for 14 h and without treatment, (b) after immersion in solutions of different pH values ​​for a certain period of time, and (c) after heating at different temperatures for a certain period of time;

[0040] Figure 3 Fluorescence emission spectra of the thienyl metal organic framework material in solid state and in different solvents provided by the present invention;

[0041] Figure 4 The fluorescence spectra and quenching efficiency of the thienyl metal organic framework material provided by the present invention for different metal ions; wherein (a) is the fluorescence emission spectrum after adding different volumes of metal ion solution, and (b) is the fluorescence emission spectrum after adding different metal ions;

[0042] Figure 5 The fluorescence spectra and quenching efficiencies of different aromatic nitro compounds of the thienyl metal organic framework material provided by the present invention, wherein (a) is the recognition effect of 2,4-dinitrophenylhydrazine at different concentrations; (b) is the recognition effect of 4-nitroaniline at different concentrations; and (c) is the recognition effect of 2-nitro-1,4-phenylenediamine at different concentrations. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] Example 1

[0045] 1) Weigh 10.0 g 1,2,4,5-tetrabromobenzene and 0.32 g PdCl 2 and 0.95g triphenylphosphine were placed in a 100mL round-bottom flask, and oxygen in the system was removed by three vacuum-nitrogen cycle operations. Then 41mL tributyl(2-thienyl)tin and 5mL N,N-dimethylformamide were added, and the temperature was raised to 130℃ for 16h. After the reaction was completed, the mixture was cooled to room temperature, filtered and washed with n-hexane to obtain a gray-black crude product. Finally, it was purified by silica gel chromatography (CH 2 Cl 2 As the eluent), white 1,2,4,5-tetra(thienyl)benzene (1) was obtained in a yield of 90%.

[0046] 2) Weigh 1 g (1) and 2.7 g NBS into a 500 mL round-bottom flask, add 45 mL tetrahydrofuran, react at room temperature for 24 h, remove the solvent by distillation under reduced pressure, and then wash with water and acetone to obtain a light yellow powder 1,2,4,5-tetrakis(5-bromothienyl)benzene (2) with a yield of 98%.

[0047] 3) Weigh 0.36 g of (2), 0.45 g of 4-methoxycarbonylphenylboronic acid, 0.05 g of tetrakistriphenylphosphine palladium and 2.50 g of potassium carbonate into a 100 mL round-bottom flask, perform vacuum evacuation and nitrogen gas flow three times, add 100 mL of 1,4-dioxane, N 2 Stir under protection at 95 °C for 48 h, cool to room temperature and remove the solvent by vacuum distillation. Add a small amount of water and then use CH 2 Cl 2 and water (V / V=1 / 1) mixed solvent extraction three times, collecting CH 2 Cl 2The organic layer was evaporated to remove the solvent to obtain a crude product, which was then purified by silica gel chromatography (CH 2 Cl 2 As the eluent) a bright yellow product 1,2,4,5-tetrakis(2-(5-(4-benzoic acid methyl ester))thienyl)benzene (3) was obtained in a yield of 50%.

[0048] 4) Weigh 0.4 g (3) and place it in a 250 mL round-bottom flask, add 40 mL of a mixed solution of methanol and tetrahydrofuran (V / V = 1 / 1), slowly add 30 mL of the prepared 2M KOH solution into the flask, and stir at 60°C until the reaction solution is clear. Remove the solvent by rotary evaporation, and slowly add dilute hydrochloric acid until a large amount of yellow floccules appear. Filter and rinse the filtrate with a large amount of water until it is neutral, and dry at 80°C for 24 hours to obtain the product 1,2,4,5-tetrakis(2-(5-(4-carboxyphenyl))thienyl)benzene (TPP), with a yield of 95%.

[0049] 5) 10 mg TPP ligand, 20 mg anhydrous ZrCl 4 The solution was placed in a 4 mL glass vial, 3 mL of anhydrous DMF solvent and 275 μL of trifluoroacetic acid were added, the solution was sealed and placed in an oven at 120° C. After 72 h, crystals were obtained with a yield of 80%.

[0050] Example 2

[0051] The difference between this embodiment and embodiment 1 is that the reaction temperature in step 5) is 100° C., and the crystals are obtained by filtration after reacting for 72 hours, with a yield of 60%.

[0052] Example 3

[0053] The difference between this embodiment and embodiment 1 is that the reaction temperature in step 5) is 110° C., and the crystals are obtained by filtration after reacting for 72 hours, with a yield of 70%.

[0054] Example 4

[0055] The difference between this embodiment and embodiment 3 is that the reaction time in step 5) is 48 hours, and after the reaction is completed, the crystals are obtained by filtration, and the yield is 50%.

[0056] Example 5

[0057] 1) Weigh 10.0 g 1,2,4,5-tetrabromobenzene and 0.32 g PdCl 2and 0.95g triphenylphosphine were placed in a 100mL round-bottom flask, and oxygen in the system was removed by three vacuum-nitrogen cycle operations. Then 41mL tributyl(2-thienyl)tin and 5mL N,N-dimethylformamide were added, and the temperature was raised to 130℃ for 16h. After the reaction was completed, the mixture was cooled to room temperature, filtered and washed with n-hexane to obtain a gray-black crude product. Finally, it was purified by silica gel chromatography (CH 2 Cl 2 As the eluent), white 1,2,4,5-tetra(thienyl)benzene (1) was obtained in a yield of 90%.

[0058] 2) Weigh 1 g (1) and 2.7 g NBS into a 500 mL round-bottom flask, add 45 mL tetrahydrofuran, react at room temperature for 24 h, remove the solvent by distillation under reduced pressure, and then wash with water and acetone to obtain a light yellow powder 1,2,4,5-tetrakis(5-bromothienyl)benzene (2) with a yield of 98%.

[0059] 3) Weigh 0.36 g of (2), 0.45 g of 4-methoxycarbonylphenylboronic acid, 0.05 g of tetrakistriphenylphosphine palladium and 2.50 g of potassium carbonate into a 100 mL round-bottom flask, perform vacuum evacuation and nitrogen gas flow three times, add 100 mL of 1,4-dioxane, N 2 Stir under protection at 95 °C for 48 h, cool to room temperature and remove the solvent by vacuum distillation. Add a small amount of water and then use CH 2 Cl 2 and water (V / V=1 / 1) mixed solvent extraction three times, collecting CH 2 Cl 2 The organic layer was evaporated to remove the solvent to obtain a crude product, which was then purified by silica gel chromatography (CH 2 Cl 2 As the eluent) a bright yellow product 1,2,4,5-tetrakis(2-(5-(4-benzoic acid methyl ester))thienyl)benzene (3) was obtained in a yield of 50%.

[0060] 4) Weigh 1g (3) and place it in a 250mL round-bottom flask, add 40mL of a mixed solution of methanol and tetrahydrofuran (V / V=1 / 1), slowly add 30mL of the prepared 2M KOH solution into the flask, and stir at 60°C until the reaction solution is clear. Remove the solvent by rotary evaporation, and slowly add dilute hydrochloric acid until a large amount of yellow floccules appear. Filter and rinse the filtrate with a large amount of water until it is neutral, and dry at 80°C for 24h to obtain the product 1,2,4,5-tetrakis(2-(5-(4-carboxyphenyl))thienyl)benzene (TPP), with a yield of 95%.

[0061] 5) 20 mg TPP ligand, 20 mg anhydrous ZrCl 4The solution was placed in a 4 mL glass vial, 3 mL of anhydrous DMF solvent and 275 μL of trifluoroacetic acid were added, and the solution was sealed and placed in an oven at 120° C. After 72 h, crystals were obtained with a yield of 70%.

[0062] Different from Example 1, the molar ratio of the 1,2,4,5-tetrakis(2-(5-(4-carboxyphenyl))thienyl)benzene organic ligand to the metal source in this example is 1:4.

[0063] In order to further illustrate the thiophene metal organic framework material prepared by the present invention and its superior performance in fluorescence detection, the following experiment was conducted.

[0064] Example 6

[0065] The single crystal diffraction data of the thiophene-based MOFs material provided in Example 1 were collected using an Agilent SuperNova X-ray single crystal diffraction system. High-quality crystals were selected and placed on the loop ring. Cu-Kα rays monochromatized by a graphite monochromator were used at 150K low temperature. As the diffraction light source, the diffraction point data of the crystal to be tested was collected in ω scanning mode. The structure was analyzed by the Superflip method of the Olex2 software package, and the structure was refined by the ShelXL method. The results are shown in Figure 1 .

[0066] Thiophene-based MOFs belong to the cubic crystal system and the Fmmm space group. Z = 4, forming a six-core eight-connected Zr 6 (μ3-O) 8 (COO) 8 (H 2 O) 8 The SBUs are further connected with ligands to construct a 3D ordered framework with larger pores in the c-axis direction.

[0067] Example 7

[0068] Weigh an appropriate amount of MOFs samples and soak and heat them in water and solutions of different pH values. After a certain period of time, take them out for powder X-ray diffraction testing. Figure 2 .

[0069] Thienyl MOFs can still maintain their structure well after being soaked in water for 14 hours, and have good water stability. The crystal structure of thienyl MOFs has partially collapsed at pH = 0, and its crystal structure can be well maintained at pH = 1 and 2. Compared with acidic conditions, thienyl MOFs are more stable under alkaline conditions. After being soaked in increasingly strong alkaline solutions with a pH of 9 to 11 for 14 hours, the crystal structure is still well maintained. When thienyl MOFs are heated to 120°C and kept for 12 hours, the peak shape changes, indicating that its crystal structure is partially destroyed, but the overall framework has not completely collapsed.

[0070] Example 8

[0071] The fluorescence spectra of thiophene MOFs were collected at room temperature using a Hitachi F-7000 fluorescence spectrophotometer. The scan rate was 1200nm·min-1, the voltage was 400V, and the excitation slit and emission slit were both 5nm. The fluorescence emission spectra of thiophene MOFs in different solvents were measured by dispersing 2mg of the material into 2mL of different solvents. The results are shown in Figure 3 .

[0072] The solid-state fluorescence emission spectra of thienyl MOFs and ligand TPP show that the maximum emission peaks of the two are basically the same, both appearing at around 518nm (λex=350nm), but under the same test conditions, the fluorescence of MOFs is significantly stronger than that of the ligand. This is mainly because after the ligand and metal ion form a polymer network, the conjugated groups are oriented in an orderly manner and the organic ligand is fixed, thereby reducing the non-radiative energy transition and enhancing the fluorescence. The maximum emission peaks of thienyl MOFs in different solvents are all around 500nm (λex=350nm), and the order of fluorescence intensity is: EtOH (ethanol)>CH3CN (acetonitrile)>DMF (N,N-dimethylformamide)>Acetone (acetone)>Toluene (toluene)>DMA (N,N-diethylformamide)>THF (tetrahydrofuran)>CH 2 Cl 2 (Dichloromethane)>TCM (chloroform)>DMSO (dimethyl sulfoxide). This may be because the polymer skeleton of MOFs is rich in S and can produce hydrogen bonding interactions with N, O, etc., resulting in differences in its dispersibility and fluorescence emission peak intensity in different solvents. Among these solvents, ethanol is most likely to produce strong hydrogen bonding, which enhances the rigidity of the polymer network and reduces non-radiative transitions, so the fluorescence performance in ethanol is the strongest.

[0073] Example 9

[0074] Thiophene-based MOFs selected 13 metal ions for metal ion recognition, including Ag + , Li + 、Zn 2+, Pd 2+ 、Zn 2+ , Mn 2+ , Pb 2+ , Cu 2+ 、Ni 2+ , Ba 2+ , Hg 2+ , Fe 2+ 、Al 2+ . Prepare 10mM DMF solutions of different metal ions, use DMF solvent as the dispersion solvent, evenly disperse 2mg of thiophene-based MOFs material in 2mL DMF, ultrasonicate for 10 minutes, and then test a series of fluorescence emission spectra after adding different volumes of metal ion solutions. The results are shown in Figure 4 .

[0075] When Fe 3+ When the solution was added to 100 μL, the quenching rate reached 84%, and when it was further added to 200 μL, the quenching rate reached 94%, further demonstrating the efficient recognition ability of thiophene-based MOFs. 2+ 、Ag + , Cu 2+ , Hg 2+ There is also a certain fluorescence response, but the other eight metal ions are almost not recognized. This result is mainly attributed to the photoinduced electron transfer mechanism, because Fe 3+ The valence electron orbital configuration is 3d54s0, which has a very high charge density. Compared with other ions, Fe 3+ The electron-rich conjugated thiophene ligands and the electron-withdrawing Fe in the thiophene-based MOFs framework are very strong electron-withdrawing 3+ Electron transfer occurs between the two species, leading to fluorescence quenching.

[0076] Example 10

[0077] Twelve nitro compounds were selected, including 2-nitro-1,4-phenylenediamine, 4-nitro-o-phenylenediamine, 2-nitroaniline, 3-nitroaniline, 4-nitroaniline, 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenylhydrazine, 1,3-dinitrobenzene, 2,4-dinitrotoluene, and 4-nitrotoluene. 10 mM DMF solutions of different nitro compounds were prepared, 2 mg of thienyl MOFs material was evenly dispersed in 2 mL DMF, ultrasonicated for 10 minutes, and then a series of fluorescence emission spectra of thienyl MOFs after adding different volumes of nitro compound solutions were tested. The results are shown in Figure 5 .

[0078] Thiophene-based MOFs are very sensitive to the recognition of phenylenediamine and phenylhydrazine nitro compounds, and also have a significant recognition effect on 4-nitroaniline in aniline nitro compounds, and have a good recognition effect on 4-nitrophenol in phenol nitro compounds, but have a poor recognition effect on toluene nitro compounds. The sensitivity ranking is: 2,4-dinitrophenylhydrazine>4-nitroaniline>2-nitro-1,4-phenylenediamine>4-nitro-o-phenylenediamine; the quenching efficiency ranking is: 2,4-dinitrophenylhydrazine (96%)>4-nitroaniline (93.2%)>2-nitro-1,4-phenylenediamine (92.1%)>4-nitro-o-phenylenediamine (89.12%). The fluorescence quenching mechanism is mainly due to the formation of hydrogen bonds between the large π-conjugated MOFs skeleton and the electron-deficient nitro compounds, and the π-π interaction causes the electrons in the LUMO orbit of the skeleton to transfer from the MOFs ligands to the explosive molecules, resulting in fluorescence quenching. The difference in fluorescence recognition performance of different nitro compounds is mainly due to the number and strength of hydrogen bonds formed. For example, the strength of hydrogen bond formation of different groups is: amino>hydroxyl>methyl, so the recognition sensitivity of thienyl MOFs to phenylhydrazine and aniline compounds is higher than that to phenol and toluene compounds.

[0079] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A thienyl metal organic framework material, characterized in that: The thienyl metal organic framework is a zirconium metal organic framework compound obtained by coordinating thiophene carboxylic acid ligands with metal zirconium ions; The thiophene carboxylic acid ligand is 1,2,4,5-tetrakis(2-(5-(4-carboxyphenyl))thienyl)benzene; the crystal structure of the thiophene metal organic framework is an orthorhombic Fmmm space group, α=β=γ=90°, Z=4.

2. A method for preparing a thienyl metal organic framework material as claimed in claim 1, characterized in that: The preparation method comprises the following steps: 1) Add 1,2,4,5-tetrabromobenzene, PdCl2 and triphenylphosphine to a reaction system, remove oxygen from the reaction system, continue to add tributyl(2-thienyl)tin and N,N-dimethylformamide solvent to the reaction system, heat to 120-150°C and react for 12-18 hours after dispersion, cool to room temperature after the reaction is completed, filter and wash with n-hexane to obtain a gray-black crude product, purify with dichloromethane as an eluent to obtain white 1,2,4,5-tetra(thienyl)benzene (1); 2) reacting (1) obtained in step 1), N-bromosuccinimide and tetrahydrofuran solvent in a reaction system at room temperature for 24-36 hours, removing the solvent by distillation under reduced pressure, washing with water and acetone respectively to obtain a light yellow powder 1,2,4,5-tetrakis(5-bromothienyl)benzene (2); 3) placing (2) obtained in step 2), 4-methoxycarbonylphenylboronic acid, tetrakistriphenylphosphine palladium, potassium carbonate and 1,4-dioxane in a reaction system, reacting at 90-120° C. for 48-96 h under N2 protection, distilling the solvent under reduced pressure, extracting with a mixed solvent of CH2Cl2 and water for multiple times, evaporating the solvent, and purifying with CH2Cl2 as an eluent to obtain a bright yellow product 1,2,4,5-tetrakis(2-(5-(4-benzoic acid methyl ester))thienyl)benzene (3); 4) placing the (3) obtained in step 3) in a reaction system containing a mixed solvent, slowly adding 1-3M KOH solution at 50-70° C. until the solution is clear, removing the solvent and slowly adding dilute hydrochloric acid dropwise until a large amount of yellow floccules appear, filtering and rinsing with water until neutral, to obtain 1,2,4,5-tetrakis(2-(5-(4-carboxyphenyl))thienyl)benzene TPP; 5) The TPP obtained in step 4) is mixed with anhydrous ZrCl4, anhydrous DMF and trifluoroacetic acid in proportion, sealed and placed in an oven at 100-120°C for 48-72h to obtain the thienyl metal organic framework material TPP-1.

3. The method for preparing the thienyl metal organic framework material according to claim 2, characterized in that: In the step 1), the molar ratio of 1,2,4,5-tetrabromobenzene, PdCl2, triphenylphosphine, tributyl(2-thienyl)tin and N,N-dimethylformamide is 14:1:2:56-84:

35.

4. The method for preparing the thienyl metal organic framework material according to claim 2, characterized in that: In the step 2), the molar ratio of (1), N-bromosuccinimide and tetrahydrofuran is 1:4-6:

220.

5. The method for preparing the thienyl metal organic framework material according to claim 2, characterized in that: In the step 3), the molar ratio of (2), 4-methoxycarbonylphenylboronic acid, tetrakistriphenylphosphine palladium, potassium carbonate and 1,4-dioxane is 12:48-72:1:420:27000, and the volume ratio of CH2Cl2 and water is 1:

1.

6. The method for preparing the thienyl metal organic framework material according to claim 2, characterized in that: In the step 4), the mass volume ratio of (3) to the mixed solvent is 1-2.5:100 g / ml, and the volume ratio of CH3OH to THF in the mixed solvent is 1:

1.

7. The method for preparing a thienyl metal organic framework material according to claim 2, characterized in that: In the step 5), the molar ratio of TPP, anhydrous ZrCl4 and trifluoroacetic acid is 1-3:8-15:300-500.

8. A thiophene-based metal organic framework material as claimed in claim 1 for fluorescence detection of Fe 3+ Application in.

9. Use of the thienyl metal organic framework material as claimed in claim 1 in fluorescence detection of aromatic nitro compounds.

10. The use according to any one of claims 8 or 9, characterized in that: When the thiophene-based metal organic framework material is subjected to fluorescence detection, the thiophene-based metal organic framework material TPP-1 obtained by the reaction is dispersed in DMF, a solution containing ions and compounds to be detected is added, and the mixture is evenly mixed and then detected by fluorescence emission spectrum.

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