A crystal material of biphenylthiourea carboxylic acid metal organic framework and a preparation method and application thereof

Abstract

A biphenylthiourea carboxylic acid metal organic framework crystal material and a preparation method and application thereof.The material has the following chemical formula: {[Zn4O(L)3]·DMF·H2O} n , wherein L is a 6-thio-6,7-dihydro-5H-dibenzo[d,f][1,3]diazepine-3,9-dicarboxylate divalent anion, and n is a degree of polymerization.The metal organic framework crystal material of the present application is synthesized by a solvothermal method, is simple to operate, has low cost, high yield, and is easy to mass industrial production.The prepared metal organic framework crystal material has a high specific surface area (a BET specific surface area of 594 m 2 / g), and an adsorption amount of CO2 of 46.0 cm 3 / g at 1 atm and 273 K.The biphenylthiourea carboxylic acid metal organic framework crystal material of the present application can efficiently catalyze a Friedel-Crafts alkylation reaction of substituted indole and substituted trans-nitrostyrene to generate an indole 3-substituted derivative, and can also efficiently catalyze a Michael addition reaction of diethyl malonate and substituted trans-nitrostyrene, both of which have mild conditions, and the catalyst can be recycled with almost no activity loss, and are good heterogeneous catalysts.

Description

Technical Field

[0001] This invention belongs to the field of preparation and application of new MOF materials, specifically involving the preparation method of metal-organic frameworks with 6-thio-6,7-dihydro-5H-dibenzo[d, f][1,3]diaza-3,9-dicarboxylic acid as ligand and their application in the fields of gas adsorption and catalysis. Background Technology

[0002] Metal-organic frameworks (MOFs) are compounds formed by the orderly connection of metal ions or metal clusters with organic ligands through coordination bonds, resulting in a highly ordered, infinite network structure. They combine the characteristics of inorganic and organic compounds and are also known as porous coordination polymers. As a unique type of coordination polymer, MOFs are characterized by their designable structure, permanent open channels, and rich functional designability. These characteristics enable them to exhibit various promising applications, such as gas storage and separation, catalysis, drug delivery, and chemical sensing. Among these, they show unique advantages in the field of heterogeneous catalysis. Compared with homogeneous catalysts, MOFs have the following advantages as heterogeneous catalysts: (1) MOFs have a regular and ordered crystal structure. This regular structure provides a reliable basis for in-depth research on structure-activity relationships and reaction mechanisms. Scientists can achieve precise design of the pore size, shape, and surface chemical properties of MOFs by designing metal nodes and organic ligands, providing efficient and highly selective catalysts for certain specific reactions; (2) They have a high specific surface area. Compared to traditional catalytic materials, MOFs typically have a large specific surface area, providing abundant active sites. A large number of active sites allow more reaction molecules to be adsorbed simultaneously on or inside the catalyst surface, thus significantly improving the rate and efficiency of the catalytic reaction; (3) MOFs exhibit good stability. Many MOF materials possess excellent chemical and thermal stability, including under harsh reaction conditions such as high temperature, strong acid, or strong alkali environments, MOFs can still maintain structural integrity, ensuring stable catalytic reactions. Furthermore, MOFs possess unique recyclability and reusability in catalysis. Due to their heterogeneous catalyst characteristics, they can be easily separated from the reaction system after the reaction is complete, and after simple processing, they can be reused without significant reduction in catalytic performance. This characteristic not only greatly reduces catalytic costs and resource waste but also aligns with the current concepts of green chemistry and sustainable development, playing a crucial role in promoting the green transformation of the chemical industry.

[0003] Dicarboxylic acid compounds, as organic linkers, possess strong coordination abilities and diverse coordination modes. 6-Thio-6,7-dihydro-5H-dibenzo[d, f][1,3]diaza-3,9-dicarboxylic acid has two carboxyl coordination sites, which, upon coordination with metal ions or metal clusters, form various nodes, ultimately resulting in structurally diverse MOF materials. Modifying the ligand structure and introducing active groups (such as thiourea groups) can enhance the adsorption capacity for CO2. Furthermore, the uniformly distributed active sites within the microporous structure of MOFs enable highly efficient heterogeneous catalysis of numerous organic reactions.

[0004] A review of the literature revealed that there are no reports of 6-thio-6,7-dihydro-5H-dibenzo[d, f][1,3]diaza-3,9-dicarboxylic acid forming MOF materials with zinc ions. Summary of the Invention

[0005] The first technical problem to be solved by the present invention is to provide a structurally stable, high specific surface area, multi-microporous metal-organic framework crystal material.

[0006] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned metal-organic framework crystal material, which is simple, environmentally friendly, low-cost, high-yield, and easy to mass-produce industrially.

[0007] A third objective of this invention is to provide the application of the aforementioned metal-organic framework crystal materials in the fields of gas adsorption and catalysis.

[0008] This invention utilizes the strong coordination ability, multiple coordination modes, easy hydrogen bonding, and aromatic ring stacking characteristics of 6-thio-6,7-dihydro-5H-dibenzo[d,f][1,3]diaza-3,9-dicarboxylic acid, and for the first time, combines the above ligand with Zn. 2+ Coordination forms a novel 3D porous metal-organic framework crystal material. These materials typically possess porosity, high specific surface area, and abundant active sites, making them promising for applications in adsorption, catalysis, chemical sensing, and drug delivery.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: The present invention discloses a biphenylthiourea carboxylic acid metal-organic framework crystal material, its preparation method, and its application, which has the following chemical formula: {[Zn4O(L)3]·DMF·H2O} n , where L is the 6-thio-6,7-dihydro-5H-dibenzo[d, f][1,3]diaza-3,9-dicarboxylate divalent anion, and n is the degree of polymerization.

[0010] The single crystal of the metal-organic framework described in this invention belongs to the cubic crystal system and has the space group Fd-3m.

[0011] The present invention discloses a biphenylthiourea carboxylic acid metal-organic framework crystal material, its preparation method, and its application, comprising the following steps: (1) The divalent zinc salt, compound 6-thio-6,7-dihydro-5H-dibenzo[d, f][1,3]diaza-3,9-dicarboxylic acid and solvent were added to a high-temperature resistant glass vial and stirred to dissolve.

[0012] (2) Heating and raising the temperature, the reactants react at a certain temperature for a period of time, then gradually lowering the temperature to room temperature, filtering, washing with DMF, drying, and obtaining metal-organic framework crystal materials.

[0013] The zinc salt compound described in this invention is one of zinc nitrate, zinc perchlorate, zinc sulfate, and zinc acetate. The zinc ions described in this invention have a +2 valence. The solvent used in this invention is DMF.

[0014] The molar ratio of the zinc salt compound to 6-thio-6,7-dihydro-5H-dibenzo[d, f][1,3]diaza-3,9-dicarboxylic acid described in this invention is 2:1 to 2:1.5; the molar ratio of the zinc salt compound to the solvent is 1:1000 to 1:3000. The reaction temperature of this invention is 80 ℃~110 ℃; The reaction time of this invention is 48-96 hours; The heating rate of this invention is 1 °C / h to 5 °C / h.

[0015] The cooling rate of this invention is 1 °C / h to 10 °C / h.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The metal-organic framework crystal material synthesized in this invention has novel, stable and porous structure.

[0017] (2) This invention uses 6-thio-6,7-dihydro-5H-dibenzo[d,f][1,3]diaza-3,9-dicarboxylic acid and Zn 2+ Using salt as a raw material, the solvothermal synthesis method is simple, easy to implement, low in cost, high in yield, and easy to scale up for industrial production.

[0018] (3) The metal-organic framework crystal material of the present invention has a three-dimensional network structure and porosity, and a high specific surface area (BET specific surface area is 594 m²). 2 It features high stability (thermal stability up to 400 °C), and at 273 K, its CO2 adsorption capacity at 1 atm is 46.0 cm³ / g. 3 / g. It can efficiently catalyze the Friedel-Crafts alkylation reaction of substituted indole with substituted trans-nitrobenzene to generate indole 3-substituted derivatives, with a maximum yield of 88%. In addition, it can also efficiently catalyze the Michael addition reaction of diethyl malonate with substituted trans-nitrostyrene. Both types of reactions are characterized by mild conditions, convenient operation, and wide substrate applicability. Moreover, the catalyst can be recycled up to 5 times with almost no loss of activity, making it suitable for large-scale application. Attached Figure Description

[0019] Figure 1 The present invention relates to the molecular structure of the biphenylthiourea carboxylic acid ligand in a metal-organic framework crystal material.

[0020] Figure 2 The present invention relates to the coordination mode of the divalent anion (L) of the biphenylthiourea carboxylic acid ligand in the metal-organic framework crystal material.

[0021] Figure 3 Secondary structural unit.

[0022] Figure 4 A perspective view of the metal-organic framework crystal material of the present invention along the C-axis.

[0023] Figure 5 The diagram shows the dual interpenetrating topos structure of the metal-organic framework crystal material of this invention.

[0024] Figure 6 Infrared spectrum of the metal-organic framework crystal material of this invention.

[0025] Figure 7 Thermogravimetric analysis of the metal-organic framework crystal material of the present invention.

[0026] Figure 8 The metal-organic framework crystal material of this invention has an N2 adsorption-desorption isotherm at 77 K.

[0027] Figure 9 The adsorption diagram of CO2 by the metal-organic framework crystal material of the present invention at 273 K. Detailed Implementation

[0028] The present invention discloses a biphenylthiourea carboxylic acid metal-organic framework crystal material, its preparation method, and its application. The synthesis and characterization steps are as follows: A divalent zinc salt compound, 6-thio-6,7-dihydro-5H-dibenzo[d, f][1,3]diaza-3,9-dicarboxylic acid, and a solvent were added to a heat-resistant glass vial. The mixture was stirred until dissolved, and then heated slowly. After the reaction proceeded at a certain temperature for a period of time, the temperature was gradually lowered to room temperature. The mixture was filtered, washed with solvent, and dried to obtain {[Zn4O(L)3]·DMF·H2O}. nCrystalline materials were then analyzed. The single-crystal structure of the compound was determined using a Bruker SMART CCD X-ray diffractometer, and the infrared spectrum of the compound was measured using a Nicolet Nexus 470 FTIR spectrometer. Thermogravimetric / differential thermal analysis of the samples was performed on a Q600 SDT thermogravimetric analyzer. Powder X-ray diffraction was performed on a Bruker D8 X-ray diffractometer. C, H, and N elemental analysis was performed on a Vario EL III elemental analyzer (Germany). Nitrogen adsorption isotherms were measured on a Quantachrome AS-1 MP instrument. 1 H NMR and 13 CNMR was tested on a Bruker Avance III HD 400MHz NMR spectrometer.

[0029] The specific implementation method is as follows: {[Zn4O(L)3]·DMF·H2O} n Synthesis and characterization 10 mg (0.03 mmol) of 6-thio-6,7-dihydro-5H-dibenzo[d, f][1,3]diaza-3,9-dicarboxylic acid ligand was placed in a 10 mL heat-resistant glass vial. Zinc nitrate hexahydrate (11 mg, 0.036 mmol, 1.2 equiv) and 4 mL of DMF were added sequentially. The mixture was stirred until dissolved, then the vial was tightly capped and placed in an automated temperature control incubator. The temperature was increased to 90 °C at a rate of 5 °C / h and maintained for 3 days. The temperature was then decreased to room temperature at a rate of 5 °C / h. The mixture was filtered to obtain lumpy yellow crystals, washed with DMF, and air-dried at room temperature to yield 8.2 mg, with a yield of 81% (based on ligand content). According to C... 48 H 33 N7O 14 The calculated elemental analysis values ​​(%) for S3Zn4 are: C, 44.71; N, 7.60; H, 2.58; experimental values ​​are: C, 44.67; N, 7.65; H, 2.52. IR (4000-400 cm⁻¹) -1 ): 3385 (vs), 3230 (vs), 1603 (s), 1544 (vs), 1399 (vs), 1371 (vs), 1165 (m), 773 (m).

[0030] Single-crystal X-ray diffraction data of the obtained compound were determined on a Bruker SMART CCD X-ray diffractometer, with data collection performed at 170 K. The diffractometer used CuKα rays at a wavelength of 1.54184 Å, with an operating voltage and current of 90 kV and 50 mA, collected in ω-scan mode. Lp factor correction was performed, and absorption correction was performed using the CrystalClear program (Müller P., Herbst-Irmer R., Spek AL, et al. International Union of Crystallography Book Series, Oxford University Press: New York, 2006, Chapter 7). The structure was resolved using the direct method, and the coordinates of all non-hydrogen atoms were determined using the difference Fourier method. Organic hydrogen atoms were obtained using the theoretical hydrogenation method, and the structure was corrected using the least squares method. The calculations were performed on a microcomputer using the SHELXTL package (Sheldrick, GM: Crystal structure refnement with SHELXL. ActaCrystallogr. 2015, C71: 3–8.), and the resulting compound structure was {[Zn4O(L)3]·DMF·H2O}. n Table 1 shows the main crystallographic data of this metal-organic framework material. Its single crystal CCDC number is 2478858.

[0031] Table 1 Figure 1 It is 6-thio-6,7-dihydro-5H-dibenzo[d, f][1,3]diaza-3,9-dicarboxylic acid.

[0032] Molecular structure diagram of the ligand. X-ray single-crystal diffraction studies show that the compound {[Zn4O(L)3]·DMF·H2O} n It belongs to the cubic crystal system, space group Fd-3m. Each asymmetric unit contains 3 L ligands, 1 coordinated O atom, and 4 Zn atoms. 2+ Each Zn 2 + It is 4-coordinated, with 3 carboxyl groups and one oxygen atom. The 3 carboxyl groups come from 3 different H2L ligands. Each carboxyl group in the H2L ligand is bidentate (κ). 1 -κ 1-μ2) mode and coordination diagram of two Zn atoms in the secondary structural unit ( Figure 2 The secondary structural unit is a tetranuclear Zn-O octahedral structure [Zn4O(CO2)6]( Figure 3 Single-crystal structure analysis confirmed that linear L maintains its two-connectivity, with each secondary structural unit acting as a six-connected node. L ligands are connected end-to-end with secondary structural units to form a pcu lattice. Figure 4 L connects with secondary structural units to form a double-interpenetrating 3D network. The topological Schläfli notation of the network is (4). 12 0.6 3 ) ( Figure 5 ).

[0033] Figure 6 The infrared spectrum of this metal-organic framework was measured on a Nicolet Nexus 470 FTIR spectrometer using spectrally pure potassium bromide pellets. Before testing, the sample and potassium bromide were dried under a UV lamp to remove surface water. The measurement range was 4000–400 cm⁻¹. -1 The infrared spectrum shows that at 3385 cm⁻¹... -1 This is the absorption peak due to the stretching vibration of the OH bond in water. 3230 cm⁻¹ -1 The absorption peak is the stretching vibration of the NH bond in the thiourea group, at 1603 cm⁻¹. -1 For υ as C=O vibration, 1544 cm -1 This is the absorption peak of the skeletal vibration of the aromatic ring υ (C=C), at 1399 cm⁻¹. -1 and 1371 cm -1 υ with carboxyl group s C=O vibration, 1165 cm -1 The absorption peak is for the CO stretching vibration, at 773 cm⁻¹. -1 This is the absorption peak of the out-of-plane bending vibration of the aromatic ring CH.

[0034] Figure 7 Thermogravimetric / differential thermal analysis (TGA / DTA) of this metal-organic framework was performed on a Q600 SDT thermogravimetric analyzer. After zeroing, 5–10 mg of sample was weighed and placed in a ceramic dry pot for measurement under a nitrogen atmosphere. The heating rate was set to 10 °C / min, reaching 800 °C. Two distinct weight loss phases were observed: a 16.7% weight loss between 30–400 °C, corresponding to the loss of one disordered water molecule and one DMF molecule from the pores; and a sharp weight loss of 32.4% between 400–550 °C, during which the organic ligands began to decompose and the framework began to collapse. The weight loss ended at 800 °C, with a total weight loss of approximately 60%.

[0035] Figure 8The nitrogen adsorption isotherm of this metal-organic framework was measured on a Quantachrome AS-1 MP instrument. Before testing, the sample was activated under vacuum at 180 °C for 24 h to remove guest molecules from the sample channels. High-purity N2 (99.999%) was used at 77 K for 10 h. -6 The N2 adsorption capacity was measured and the BET specific surface area was calculated within a pressure range of -1. This physical adsorption-desorption isotherm is a typical microporous adsorption isotherm (type I), and its BET specific surface area was calculated to be 594 m². 2 / g.

[0036] Figure 9 The adsorption capacity of this metal-organic framework for CO2 at 0.1–1 atm and 273 K was determined using a Quantachrome AS-1 MP instrument. Before testing, the sample was activated under vacuum at 180 °C for 24 h to remove guest molecules from the sample channels. High-purity CO2 was used. The CO2 adsorption capacity was 46.0 cm⁻¹. 3 / g.

[0037] Catalytic reaction one: The Friedel-Crafts alkylation reaction of substituted indole and substituted trans-nitrostyrene catalyzed by the biphenylthiourea carboxylic acid metal-organic framework crystal material in the examples was carried out as follows: substituted indole (1.0 mmol), substituted trans-nitrostyrene (1 mmol), and catalyst {[Zn4O(L)3]·DMF·H2O} were added to a 10 mL reaction tube, respectively. n (15 mg, 1 mol%), then toluene (2.0 mL), and the reaction was stirred at 70 °C for 24 hours. The reaction was monitored by TLC. After the reaction was completed, the reaction solution and catalyst were separated by centrifugation. The reaction solution was concentrated and purified by silica gel column chromatography to obtain the product. The product was purified by column chromatography (eluent: petroleum ether: ethyl acetate = 15:1). The NMR spectrometer was used to test the structure of the target product using a Brucker Avance III HD 400MHz NMR spectrometer, with CDCl3 as solvent and TMS as internal standard. The substrate universality test results are shown in Table 2. The catalytic reaction formula is: Table 2 As shown in Table 2, the catalyst biphenylthiourea carboxylic acid metal-organic framework crystal material in the examples has good catalytic performance, broad substrate versatility, and can catalyze different types of substrate reactions with high reaction yield.

[0038] In the cyclic catalytic experiments, indole and trans-nitrostyrene were used as reaction substrates. After each catalytic reaction, the catalyst was separated by centrifugation, filtered, washed with ethanol, and activated under vacuum at 100 °C for 24 h to serve as the catalyst for the next cycle. The product yields of the five cycles were 85%, 84%, 82%, 78%, and 77%, respectively.

[0039] Catalytic reaction two: The Michael addition reaction of diethyl malonate with substituted trans-nitrostyrene catalyzed by the biphenylthiourea carboxylic acid metal-organic framework crystal material in the examples was carried out as follows: Diethyl malonate (1.0 mmol), trans-nitrostyrene (1 mmol), N,N-diisopropylethylamine (1 mmol), and catalyst {[Zn4O(L)3]·DMF·H2O} were added to a 10 mL reaction tube. n (15 mg, 1 mol%), then toluene (2.0 mL), and the reaction was stirred at room temperature for 16 hours. The reaction was monitored by TLC. After the reaction was completed, the reaction solution and catalyst were separated by centrifugation. The reaction solution was concentrated and purified by silica gel column chromatography to obtain the product. The product was purified by column chromatography (eluent: petroleum ether: ethyl acetate = 12:1). The NMR of the target product was characterized using a Brucker Avance III HD 400MHz NMR spectrometer with CDCl3 as solvent and TMS as internal standard. The substrate universality test results are shown in Table 3. The catalytic reaction formula is: Table 3 As shown in Table 3, the catalyst biphenylthiourea carboxylic acid metal-organic framework crystal material in the examples has good catalytic performance, broad substrate versatility, and can catalyze different types of substrate reactions with high reaction yield.

[0040] The cyclic catalytic experiments used diethyl malonate and trans-nitrostyrene as reaction substrates. After each catalytic reaction, the catalyst was separated by centrifugation, filtered, washed with ethanol, and activated under vacuum at 100 °C for 24 h to serve as the catalyst for the next cycle. The product yields of the five cycles were 87%, 87%, 85%, 82%, and 78%, respectively.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments without departing from the technical essence of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a biphenylthiourea carboxylic acid metal-organic framework crystal material, characterized in that: It includes the following steps: Step 1: Add the divalent zinc salt compound, 6-thio-6,7-dihydro-5H-dibenzo[d, f][1,3]diaza-3,9-dicarboxylic acid and solvent to a high-temperature resistant glass vial and stir to dissolve; Step 2: Slowly heat to 80℃~110℃ at a heating rate of 1 °C / h~5 °C / h, react for 48~96 hours, then gradually decrease the temperature at a cooling rate of 1 °C / h~10 °C / h, cool to room temperature, filter, wash, and dry the filter cake to obtain the metal-organic framework crystal material; the chemical formula is as follows: {[Zn4O(L)3]·DMF·H2O} n , where L is the abbreviation for 6-thio-6,7-dihydro-5H-dibenzo[d, f][1,3]diaza-3,9-dicarboxylate divalent anion; The molecular structural formula of L is: In the above chemical formula: L is a divalent anion of 6-thio-6,7-dihydro-5H-dibenzo[d, f][1,3]diaza-3,9-dicarboxylate; The degree of aggregation is n.

2. The method for preparing the biphenylthiourea carboxylic acid metal-organic framework crystal material according to claim 1, characterized in that: The metal-organic framework single crystal belongs to the cubic crystal system with space group Fd-3m.

3. The method for preparing the biphenylthiourea carboxylic acid metal-organic framework crystal material according to claim 1, characterized in that: The molar ratio of the zinc salt compound to 6-thio-6,7-dihydro-5H-dibenzo[d, f][1,3]diaza-3,9-dicarboxylic acid is 2:1 to 2:1.5; the molar ratio of the zinc salt compound to the solvent is 1:1000 to 1:3000.

4. The method for preparing the biphenylthiourea carboxylic acid metal-organic framework crystal material according to claim 1, characterized in that: The zinc salt is one of zinc nitrate, zinc perchlorate, zinc sulfate, and zinc acetate.

5. The method for preparing the biphenylthiourea carboxylic acid metal-organic framework crystal material according to claim 1, characterized in that: The solvent used in both steps one and two is N,N-dimethylformamide (DMF).

6. A biphenylthiourea carboxylic acid metal-organic framework crystal material, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 5.

7. Application of biphenylthiourea carboxylic acid metal-organic framework crystal materials, characterized by: Applications of this metal-organic framework crystal material in gas adsorption and heterogeneous catalytic organic reactions.

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