Ligand with tert-butyl group, two-dimensional copper-based blocky metal organic framework material as well as preparation method and application of ligand and two-dimensional copper-based blocky metal organic framework material

Abstract

The invention discloses a ligand with a tert-butyl group, a two-dimensional copper-based blocky metal organic framework material as well as a preparation method and application of the two-dimensional copper-based blocky metal organic framework material. The preparation method comprises the following steps: carrying out coordination reaction on a 3, 6-di-tert-butyl carbazole-carboxyl ligand with a large group and copper ions under a solvothermal condition to form a high-crystallinity two-dimensional main body framework; the framework material has catechol oxidase-like activity. And a tert-butyl group is introduced to weaken a pi-pi accumulation effect between two-dimensional layers, so that a blocky material is easier to strip to obtain the nanosheet. More active sites are exposed out of the stripped nanosheets, so that the reaction with a substrate is facilitated, and the catalytic performance is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal organic framework functional materials, and specifically relates to a ligand with a tert-butyl group, a two-dimensional copper-based bulk metal organic framework material, and a preparation method and application thereof. Background Art

[0002] In the past few decades, two-dimensional (2D) nanomaterials, such as graphene, graphdiyne, metal sulfides, black phosphorus, and MXenes, have attracted extensive attention due to their unique properties. Compared with three-dimensional (3D) bulk materials, the inherent ultrathin structure of 2D nanomaterials endows them with various advantages, such as excellent mechanical flexibility, good optical transparency, large specific surface area, ultrahigh surface area to volume atomic ratio, and abundant accessible active sites. However, the chemical and functional designability of the above 2D nanomaterials is poor.

[0003] As a new type of two-dimensional nanomaterial, two-dimensional metal-organic framework (2D MOF) nanosheets with high designability have become one of the research hotspots. MOFs combine the tunability of organic linkers with the unique properties of metal ions, allowing the creation of diverse, well-defined architectures with customized properties. This flexibility enables their development for a variety of applications ranging from "smart" materials and sensors to light harvesting, gas storage, and drug delivery. To date, existing studies have utilized several synthetic methods to obtain 2D MOF nanosheets, which can be divided into two main aspects: bottom-up synthesis and top-down layering. Bottom-up methods, including interfacial synthesis technology, aqueous solvothermal synthesis, surfactant-assisted synthesis, modulation synthesis, and template synthesis, are methods for directly synthesizing 2D MOF nanosheets from metal ions and carefully designed organic linkers. Top-down methods refer to the decomposition of bulk MOF materials into single or multilayers, including physical or chemical exfoliation techniques such as ultrasonic exfoliation, shaking treatment, mechanical exfoliation, solvent-induced layering, lithium intercalation, etc. However, although mechanical exfoliation is simple and easy, it is more random, difficult to control, and has a very low yield. The exfoliated nanosheets are of different sizes. Summary of the invention

[0004] Based on the above reasons, the first object of the present invention is to provide a ligand with a tert-butyl group, wherein the organic ligand itself can construct a two-dimensional bulk metal-organic framework material with metal ions, wherein the tert-butyl group structure can weaken the π-π stacking effect in the two-dimensional layer, thereby obtaining a high-yield nanosheet by mechanical exfoliation.

[0005] The second purpose of the present invention is to provide a two-dimensional copper-based bulk metal-organic framework material that has the ability to catalyze the oxidation of catechol and can obtain high-yield nanosheets through mechanical exfoliation, exposing more metal active sites, promoting the adsorption and activation of reaction substrates, and improving catalytic performance.

[0006] The third purpose of the present invention is to provide a method for preparing a two-dimensional copper-based bulk metal organic framework material, wherein an organic ligand and a metal ion precursor undergo a coordination reaction to self-assemble to form a two-dimensional layered structure; and a two-dimensional MOF nanosheet is obtained by mechanical exfoliation under a solvent.

[0007] The fourth object of the present invention is to provide an application of a two-dimensional copper-based bulk metal organic framework material in simulating natural catechol oxidase.

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

[0009] A ligand with a tert-butyl group has a structure shown in Formula I:

[0010]

[0011] Where R is n is 0, 1 or 2.

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

[0013] A method for preparing a two-dimensional copper-based bulk metal-organic framework material, comprising: conducting a solvothermal reaction between a structural ligand shown in formula I and a copper ion precursor to obtain the two-dimensional copper-based bulk metal-organic framework material.

[0014] Furthermore, the copper ion precursor is an acetic acid, hydrochloric acid, sulfuric acid or nitric acid compound of divalent copper ion and a hydrate thereof.

[0015] Furthermore, the molar ratio of the ligand of the structure shown in Formula I to the divalent copper ion precursor is 1:(1-1.2).

[0016] Furthermore, the solvent for the solvothermal reaction is a mixed solvent of N,N-diethylformamide and methanol, and the volume ratio of N,N-diethylformamide to methanol is 1:(1-4).

[0017] Furthermore, the molar volume ratio of the ligand of the structure shown in Formula I to the solvent is (5-10) mmol:1 mL.

[0018] Furthermore, the reaction temperature is 70-100°C; and the reaction time is 12-96h.

[0019] Furthermore, the reaction includes a separation and washing process; after separation, the solid is washed with N,N-diethylformamide and methanol respectively, and vacuum dried to obtain the two-dimensional copper-based bulk metal organic framework material.

[0020] Furthermore, the method further comprises a stripping step:

[0021] The two-dimensional copper-based bulk metal-organic framework material is sheared and mixed in tetrahydrofuran, and peeled to obtain two-dimensional copper-based bulk metal-organic framework material nanosheets.

[0022] Further, the shear mixing is performed in a high shear laboratory mixer at a shear speed of 4000-6000 rpm and a shear mixing time of 1-5 h.

[0023] The third object of the present invention can be achieved by adopting the following technical solutions:

[0024] A two-dimensional copper-based bulk metal-organic framework material is prepared by any of the above-mentioned methods for preparing the two-dimensional copper-based bulk metal-organic framework material.

[0025] The fourth object of the present invention can be achieved by adopting the following technical solutions:

[0026] The use of any of the above-mentioned two-dimensional copper-based bulk metal organic framework materials as a natural catechol oxidase-mimicking enzyme in catalytic oxidation.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The ligand with a tert-butyl group of the present application has a basic skeleton connected by carbazole and phenyl, in which the carboxyl group can act as a reaction site to coordinate with metal ions to form a two-dimensional metal-organic framework with high crystallinity; and the tert-butyl group on the ligand can weaken the π-π stacking effect in the two-dimensional layer, thereby facilitating the acquisition of high-yield nanosheets by mechanical exfoliation.

[0029] 2. The preparation method of the two-dimensional copper-based bulk metal organic framework material of the present application forms a two-dimensional metal organic framework material through the coordination connection of the ligand and the metal ion by the solvothermal reaction, has an infinite kagome-type two-dimensional layered structure, and the preparation method is simple. And a nanosheet structure material with a high yield can be obtained by mechanical exfoliation.

[0030] 3. The two-dimensional copper-based bulk metal-organic framework material of the present application has a basic skeleton connected by carbazole and phenyl and a copper ion coordination site. It has an active center that mimics natural catechol oxidase and can form more active nanosheets through peeling, providing excellent catalytic performance; it has the ability to catalyze the oxidation of catechol. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Ligand H prepared in Example 2 H NMR spectrum of TBDI;

[0032] Figure 2 Ligand H prepared in Example 213C NMR spectrum of TBDI

[0033] Figure 3 X-ray powder diffraction patterns of the CuTBDI Bulk crystal prepared in Example 3 and the CuTBDI NS nanosheets prepared in Example 6;

[0034] Figure 4 Topological structure diagram of CuTBDI prepared in the examples;

[0035] Figure 5 Transmission electron microscope images and atomic force microscope images of CuTBDI prepared in the examples;

[0036] Figure 6 Infrared spectrum diagram of CuTBDI prepared in the examples;

[0037] Figure 7 Oxidation activity diagrams of CuTBDI Bulk (a) and CuTBDI-NS (b) towards 3,5-DTBC;

[0038] Figure 8 Oxidation activity diagrams of CuTBDI Bulk (a) and CuTBDI-NS (b) towards different concentrations of 3,5-DTBC;

[0039] Fig. 9 Diagram showing the influence of gas environment on the oxidation activity of CuTBDI Bulk and CuTBDI-NS towards 3,5-DTBC. Detailed implementation manners

[0040] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0041] Two-dimensional bulk metal-organic framework materials have serious π-π stacking and covered active sites, which to a certain extent limit their development in various fields. Although mechanical exfoliation is simple and easy to perform, it has a large randomness, is difficult to control and has a very low yield, and the sizes of the exfoliated nanosheets are not uniform. Therefore, the simple mechanical exfoliation method cannot exfoliate two-dimensional bulk metal-organic framework materials into high-performance nanosheets.

[0042] Catechol oxidase is a naturally occurring copper-based enzyme that catalyzes the oxidation of catechol to quinone. MOF-818 containing trinuclear copper has been reported to have highly specific catecholase activity (J.Am.Chem.Soc.2020,142,15569-15574). The metal-ligand synergy and optimized electronic and structural properties of the metal-organic framework give it specific oxidase-mimicking activity.

[0043] Therefore, the present application provides a ligand with a tert-butyl group, a two-dimensional copper-based bulk metal-organic framework material, and a preparation method and application thereof.

[0044] A ligand with a tert-butyl group has a structure shown in Formula I:

[0045]

[0046] Where R is n is 0, 1 or 2.

[0047] The ligand of the present application has a main structure of carbazole and phenyl connection, which provides in-plane extension, wherein the carboxyl groups at positions 3 and 5 on the benzene ring can coordinate with metal ions to form a metal organic framework; in particular, the tert-butyl group connected to the carbazole ring can weaken the π-π stacking effect in the two-dimensional layer, thereby weakening the interaction between layers and being more conducive to layer peeling.

[0048] The above-mentioned ligand of the present application is prepared by the following process:

[0049]

[0050] Where R is n is 0, 1 or 2.

[0051] 3,6-Di-tert-butyl-9H-carbazole and dimethyl 5-iodophthalate in cuprous iodide / 1,4,7,10,13,16-hexaoxacyclooctadecane / Cs 2 CO 3 The system is used to react in a DMF solution, and then the ester group is hydrolyzed and acidified to obtain a ligand having a structure shown in formula I.

[0052] As one embodiment, the reaction is carried out at 150-180° C. for 12-72 hours.

[0053] A method for preparing a two-dimensional copper-based bulk metal-organic framework material, comprising: conducting a solvothermal reaction between a structural ligand shown in formula I and a copper ion precursor to obtain the two-dimensional copper-based bulk metal-organic framework material.

[0054] In the structural ligand shown in Formula I of the present application, a phenyl group is connected to the N of carbazole, and the carboxyl groups at the 3 and 5 positions of the phenyl group coordinate with the copper ion. One carboxyl group of each of the two adjacent ligands forms a Cu(II)-paddlewheel unit with the copper ion; the ligand and the Cu(II)-paddlewheel unit are infinitely extended to form a kagome-type two-dimensional layered structure.

[0055] As one embodiment, the divalent cupric ion precursor is an acetic acid, hydrochloric acid, sulfuric acid or nitric acid compound of divalent cupric ion and its hydrate. Preferably, the divalent cupric ion precursor is Cu(NO 3 ) 2 ·3H 2 O.

[0056] As one embodiment thereof, the molar ratio of the ligand of the structure shown in Formula I to the divalent copper ion precursor is 1:(1-1.2).

[0057] As one embodiment, the solvent for the solvothermal reaction is a mixed solvent of N,N-diethylformamide and methanol, and the volume ratio of N,N-diethylformamide to methanol is 1:(1-4).

[0058] As one embodiment, the molar volume ratio of the ligand of the structure shown in Formula I to the solvent is (5-10) mmol:1 mL.

[0059] As one embodiment, the reaction temperature is 70-100° C. and the reaction time is 12-96 hours.

[0060] As one embodiment, a separation and washing process is included after the reaction; after separation, the solid is washed with N,N-diethylformamide and methanol respectively, and vacuum dried to obtain the two-dimensional copper-based bulk metal organic framework material.

[0061] As one embodiment thereof, the step of stripping is also included:

[0062] The two-dimensional copper-based bulk metal-organic framework material is sheared and mixed in tetrahydrofuran, and peeled to obtain two-dimensional copper-based bulk metal-organic framework material nanosheets.

[0063] The ligand carbazole and benzene ring structure in the formed two-dimensional copper-based bulk metal organic framework material also have π-π stacking and active site coverage. However, the carbazole in the ligand is connected to two tert-butyl group structures, located between layers, which can weaken the π-π stacking effect in the two-dimensional layered structure, which makes it possible to peel the layered structure through mechanical peeling method to obtain high-yield nanosheets.

[0064] Compared with bulk crystals, the nanosheet materials obtained by exfoliation match the main framework, and the thickness of the nanosheet materials is reduced to a few nanometers, exposing more metal active sites, which is conducive to promoting the adsorption and activation of reaction substrates and has the advantage of efficient catalysis.

[0065] As one embodiment, the shear mixing is performed in a high shear laboratory mixer at a shear speed of 4000-6000 rpm and a shear mixing time of 1-5 h.

[0066] In the present application, the exfoliation of the two-dimensional copper-based bulk metal organic framework material can be achieved by adopting a high-speed shearing method, but it needs to be in the solvent tetrahydrofuran.

[0067] The two-dimensional copper-based bulk metal organic framework material and nanosheet prepared in the present application have an active center that mimics the natural catechol oxidase, and thus have the ability to catalyze the oxidation of catechol and can be used as a bionic catalyst in catalytic reactions.

[0068] The following is a further description with reference to specific embodiments.

[0069] Example 1

[0070] A 100 mL flame-dried reaction bottle was charged with 3,6-di-tert-butyl-9H-carbazole (1.484 g, 5.313 mmol), dimethyl 5-iodophthalate (1.000 g, 3.125 mmol), cuprous iodide (0.595 g, 3.125 mmol), 1,4,7,10,13,16-hexaoxacyclooctadecane (0.083 g, 0.313 mmol) and Cs 2 CO 3 (0.734 g, 5.313 mmol), and the flask was degassed and then heated with N 2 Refill three times; add 40 mL of degassed N,N-dimethylformamide under nitrogen protection, and heat the suspension at 170°C for 36 h; after cooling to room temperature, remove inorganic salts by filtration, and extract the resulting mixture with saturated brine and ethyl acetate; the combined organic extracts are washed with anhydrous Na 2 SO 4 Dry and then concentrate under reduced pressure. The crude solid was purified by silica gel column chromatography (DCM / petroleum ether, 1:20, v / v) to give dimethyl 5-(3,6-di-tert-butyl-9H-carbazol-9-yl)isophthalate (S1, 0.985 g, 66.81%) as a white solid.

[0071] Example 2

[0072] S1 (0.985 g, 2.089 mmol) and sodium hydroxide (1.26 g, 12.534 mmol) were dissolved in THF (12 mL), MeOH (25 mL) and H 2 O (25 mL), the solution was heated at 65 ° C for 12 h; the solution was cooled to room temperature, and THF and MeOH were removed by vacuum evaporation; after adding 50 mL of deionized water to the round-bottom flask, dilute hydrochloric acid was gradually introduced into the remaining aqueous solution until the solution reached pH = 2; the precipitate was filtered, washed with deionized water, and dried at 60 ° C to obtain H 2 TBDI (0.880 g, 95%). Figure 1 As shown in the NMR carbon spectrum Figure 2 shown.

[0073] Example 3

[0074] Weigh H 2 TBDI 6.76mmol and Cu(NO 3 ) 2 ·3H 2 O 6.66mmol was placed in a glass tube (8×150mm), 0.3ml of N,N-diethylformamide and 0.6ml of methanol were added, and the mixture was then ultrasonically treated for 10min; the glass tube was sealed with a hydrogen-oxygen flame and heated in an oven at 80°C for 36h, and then naturally cooled to room temperature. The crystals were collected by filtration, and the crystal samples were washed with N,N-diethylformamide (5mL×5) and methanol (5mL×5), and dried in an oven at 65°C for 2h to obtain a two-dimensional copper-based bulk metal-organic framework material, named CuTBDI Bulk crystal (yield: 79%).

[0075] Example 4

[0076] Weigh H 2 TBDI 6.76mmol and CuCl 2 7.44mmol was placed in a glass tube (8×150mm), 0.34ml of N,N-diethylformamide and 0.34ml of methanol were added, and the mixture was then ultrasonically treated for 10min; the glass tube was sealed with a hydrogen-oxygen flame and heated in an oven at 100℃ for 12h, and then naturally cooled to room temperature. The crystals were collected by filtration, and the crystal samples were washed with N,N-diethylformamide (5mL×5) and methanol (5mL×5), and dried in an oven at 65℃ for 2h to obtain a two-dimensional copper-based bulk metal-organic framework material, named CuTBDI Bulk crystals.

[0077] Example 5

[0078] Weigh H 2 TBDI 6.76mmol and Cu(CH3 COO 2 ·H 2 O 8.11mmol was placed in a glass tube (8×150mm), 0.25ml of N,N-diethylformamide and 1.0ml of methanol were added, and the mixture was then ultrasonically treated for 10min; the glass tube was sealed with a hydrogen-oxygen flame and heated in an oven at 70°C for 96h, and then naturally cooled to room temperature. The crystals were collected by filtration, and the crystal samples were washed with N,N-diethylformamide (5mL×5) and methanol (5mL×5), and dried in an oven at 65°C for 2h to obtain a two-dimensional copper-based bulk metal-organic framework material, named CuTBDI Bulk crystal.

[0079] Example 6

[0080] 70 mg of CuTBDI Bulk prepared in Example 3 and 140 mL of tetrahydrofuran were added to a 500 mL beaker; the mixture was then shear mixed at 5000 rpm for 3 h using a high shear laboratory mixer (L5M, Silverson Machines, East Longmeadow); the resulting suspension was allowed to stand overnight to remove unpeeled bulk materials, and the supernatant was then centrifuged at 12500 rpm to obtain two-dimensional copper-based bulk metal-organic framework nanosheets; named CuTBDINS (yield: 61%), washed with tetrahydrofuran and dried.

[0081] Test example:

[0082] (1) X-ray powder diffraction test was performed on the CuTBDI Bulk crystals prepared in Example 3 and the CuTBDI NS nanosheets prepared in Example 6; the powder X-ray diffraction pattern is as follows: Figure 3 As shown; the structural simulation diagram is as follows Figure 4 shown.

[0083] from Figure 3 The PXRD pattern of CuTBDI NS shows that the material matches CuTBDI Bulk, the MOF nanosheets maintain the crystallinity of the bulk MOF framework, and the PXRD peak intensity weakens but the position remains unchanged, indicating that no ligand structure change has occurred.

[0084] from Figure 4 The results of single crystal X-ray diffraction tests show that CuTBDI Bulk crystallizes in the monoclinic space group C2 / c, in which the asymmetric unit contains three Cu 2+ , three TBDI 2-, an N,N-diethylformamide molecule, a methanol molecule, and a water molecule. In this structure, the Cu(II)-paddlewheel units are interconnected through isophthalate units to form an infinite kagomé-type two-dimensional layered structure. The interlayer distance of the CuTBDI block is There are two coordination modes in the axial position of the paddle wheel. One coordination mode is that both ends of the shaft are N, N-diethylformamide molecules, and the other is that one end is a methanol molecule and the other end is a water molecule.

[0085] (2) The CuTBDI NS nanosheets prepared in Example 6 were observed by transmission electron microscopy and analyzed by atomic force microscopy. The transmission electron microscopy images are shown in FIG. Figure 5 As shown in a, the atomic force microscope image is Figure 5 As shown in b.

[0086] from Figure 5 Wrinkled or broken sheets were observed in the TEM of a, indicating the thin nature of the exfoliated nanosheets. Moreover, the exfoliation process occurred instantly, as evidenced by the Tyndall effect after laser beam irradiation. Figure 5 b Atomic force microscopy (AFM) analysis showed that the thickness of these nanosheets ranged from 10 nm. Both characterization methods showed that independent nanosheets with sizes up to nanometers were obtained after exfoliation. CuTBDI bulk can be exfoliated into nanosheets, namely CuTBDINS, by stirring in a high shear mixer.

[0087] (3) H prepared in Example 2 2 TBDI, CuTBDI Bulk crystals prepared in Example 3 and CuTBDI NS prepared in Example 6 were subjected to infrared spectroscopy analysis. The infrared spectra are shown in FIG. Figure 6 shown.

[0088] from Figure 6 It can be observed in the infrared spectrum that based on the carboxylic acid ligand H 2 TBDI, 2507cm -1 and 2622cm -1 The two broad peaks at 1705 cm-1 are the two characteristic peaks of the -OH group on the carboxylic acid. -1 A strong absorption peak appears at 2843-3000cm, which is the characteristic peak of carbonyl in carboxylic acid. -1 The characteristic peak at is attributed to H 2 Stretching vibration of the CH bond of tert-butyl in TBDI. When the ligand is deprotonated and coordinated with copper ions to form CuTBDI Bulk, the characteristic peak of the carbonyl group shifts from 1705 cm -1 Move to 1633cm -1 The two characteristic peaks of -OH in the carboxyl group disappeared, proving that the ligand H 2The carboxylic acid of TBDI was successfully coordinated with divalent copper ions. The absorption peaks belonging to the ligand in the fingerprint region remained basically unchanged.

[0089] Experimental example:

[0090] To study the catechol oxidation performance of CuTBDI Bulk and CuTBDI NS, CuTBDI Bulk prepared in Example 3 and CuTBDI NS prepared in Example 6 (20 mL, 0.1 mg mL -1 ) were separately added to a reaction flask together with 10 mL of 5 mM 3,5-DTBC (3,5-di-tert-butylcatechol). The absorbance corresponding to 3,5-di-tert-butylbenzoquinone at λ max = 401 nm was monitored using a UV-visible spectrophotometer. The change in the intensity of the absorption peak at 401 nm as the reaction proceeded is as Figure 7 shown. Where a is CuTBDI Bulk; b is CuTBDI NS.

[0091] From Figure 7 it can be seen that as the reaction proceeds, due to the oxidation of 3,5-DTBC by CuTBDI Bulk and CuTBDI NS, the intensity of the absorption peak at 401 nm increases. Figure 7 The increase in the intensity of the absorption peak in b is more than Figure 7 that in a. It can be seen that since more metal sites of the exfoliated CuTBDI NS nanosheets are exposed, it is more conducive to interacting with the substrate, thus obtaining better performance than CuTBDI Bulk.

[0092] In addition, the effect of the 3,5-DTBC concentration on the reaction rate was also measured. For a detailed analysis, time-dependent spectral scans were performed on mixtures of CuTBDI Bulk and CuTBDI NS with 3,5-DTBC having a fixed catalyst concentration (100 μg / mL) and a series of different substrate concentrations (0.1, 0.2, 0.25, 0.5, 1.0, 1.5, 2.0 mM). The results are as Figure 8 shown, where a is CuTBDI Bulk; b is CuTBDI NS.

[0093] From Figure 8 it can be seen that as the concentration of 3,5-DTBC increases, the reaction rate of CuTBDI Bulk to form CuTBDI NS after exfoliation increases.

[0094] In addition, the effect of the gas environment on the reaction was also measured. CuTBDI Bulk and CuTBDI NS were used to oxidize 3,5-DTBC under saturated O 2 , air, and argon, and the UV-visible absorption spectra are as Fig. 9 shown.

[0095] Fig. 9 The results show that the absorption of 3,5-DTBC catalyzed by CuTBDI Bulk and CuTBDI NS is higher in O compared with the absorption at 401 nm in air saturated solution. 2 It increased significantly under saturated conditions and decreased under Ar saturated conditions. These indicate that oxygen is required for this reaction.

[0096] In summary, the present application has developed a two-dimensional copper-based metal organic framework material with catechol oxidase-like activity, and a 3,6-di-tert-butylcarbazole-carboxyl ligand with a large group is coordinated with copper acetate monohydrate under solvent thermal conditions to form a highly crystalline two-dimensional main framework. By introducing a tert-butyl group to weaken the π-π stacking effect between the two-dimensional layers, the bulk material is easier to peel off to obtain nanosheets. Therefore, a simple mechanical peeling method is adopted, and the nanosheets obtain a medium yield. The peeled nanosheets expose more active sites, which are more conducive to reaction with substrates, thereby improving performance and having higher catalytic ability than two-dimensional copper-based metal organic framework materials.

[0097] 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 ligand with a tert-butyl group, characterized in that: It has the structure shown in formula I: Where R is n is 0, 1 or 2.

2. A method for preparing a two-dimensional copper-based bulk metal organic framework material, characterized in that: The structural ligand shown in formula I of claim 1 and the copper ion precursor undergo a solvothermal reaction to obtain the two-dimensional copper-based bulk metal-organic framework material.

3. The method for preparing a two-dimensional copper-based bulk metal organic framework material according to claim 2, characterized in that: The copper ion precursor is an acetic acid, hydrochloric acid, sulfuric acid or nitric acid compound of divalent copper ion and a hydrate thereof.

4. The method for preparing a two-dimensional copper-based bulk metal organic framework material according to claim 2, characterized in that: The molar ratio of the ligand of the structure shown in Formula I to the divalent copper ion precursor is 1:(1-1.2).

5. The method for preparing a two-dimensional copper-based bulk metal organic framework material according to claim 2, characterized in that: The solvent for the solvothermal reaction is a mixed solvent of NN-diethylformamide and methanol. The volume ratio of N,N-diethylformamide to methanol is 1:(1-4); The molar volume ratio of the ligand of the structure shown in Formula I to the solvent is (5-10) mmol:1 mL; The reaction temperature is 70-100°C; the reaction time is 12-96h.

6. The method for preparing a two-dimensional copper-based bulk metal organic framework material according to claim 2, characterized in that: The reaction includes a separation and washing process; after separation, the solid is washed with N, N-diethylformamide and methanol respectively, and vacuum dried to obtain the two-dimensional copper-based bulk metal organic framework material.

7. The method for preparing a two-dimensional copper-based bulk metal organic framework material according to claim 2, characterized in that: Also includes a stripping step: The two-dimensional copper-based bulk metal-organic framework material is sheared and mixed in tetrahydrofuran, and peeled to obtain two-dimensional copper-based bulk metal-organic framework material nanosheets.

8. The method for preparing a two-dimensional copper-based bulk metal organic framework material according to claim 7, characterized in that: The shear mixing was carried out in a high shear laboratory mixer at a shear speed of 4000-6000 rpm and a shear mixing time of 1-5 h.

9. A two-dimensional copper-based bulk metal organic framework material, characterized in that: The two-dimensional copper-based bulk metal organic framework material is prepared by the preparation method of any one of claims 2 to 8.

10. Use of the two-dimensional copper-based bulk metal organic framework material according to any one of claims 2 to 9 as a natural catechol oxidase-mimicking enzyme in catalytic oxidation.

Images