Preparation method and application of coordination polymer nanowire for catalyzing functionalization of C-H bond

Abstract

The invention discloses a preparation method and application of a coordination polymer nanowire for catalyzing C-H bond functionalization, and belongs to the technical field of photocatalytic materials. According to the preparation method, a Cu-Cl chromophore is taken as a node, L is taken as a ligand, a three-dimensional chain-shaped coordination polymer material is constructed through a solvothermal synthesis strategy, and then the superfine coordination polymer nanowire with high catalytic activity is effectively prepared by adopting a solvent-assisted ultrasonic stripping technology. The prepared nanowire material is stable in chemical property and easy to put into practical application, and the accessibility of active sites can be greatly improved and the influence of the diffusion effect can be effectively inhibited in the catalysis process. A large number of Cu-Cl chromophores are uniformly distributed on the superfine one-dimensional nanowire, and the Cu-Cl chromophores and the photosensitive ligand L can activate inert C-H bonds and a green oxidant oxygen under light excitation so as to complete the functionalization process of the inert C-H bonds with high efficiency and high selectivity.

Description

Technical Field

[0001] This invention relates to a method for preparing coordination polymer nanowires that catalytically functionalize CH bonds and their applications, belonging to the field of coordination polymer catalytic materials technology. Background Technology

[0002] Heterogeneous industrial catalysts have important applications in industrial production due to their high catalytic efficiency and excellent recycling characteristics. Therefore, heterogeneous modification of highly efficient molecular catalysts to adapt them to the needs of industrial processes has become a challenging and significant research task. Among the reported heterogeneous catalytic systems, coordination polymers have become an important catalytic platform due to their programmable structure. Through precise molecular-level design of their organic ligands and metal nodes, the immobilization and efficient utilization of molecular catalysts in heterogeneous transformation processes can be achieved. However, three-dimensional (3D) coordination polymer structures generally suffer from diffusion effects, making it difficult for reactants to contact internal active sites and for products to rapidly desorb and diffuse. In recent years, two-dimensional (2D) polymer nanosheets have attracted attention due to their ultrathin thickness, good flexibility, and high substrate permeability, becoming an advantageous platform in fields such as photoelectric response, electron transport, and catalytic conversion. Two-dimensional nanosheets reduce the diffusion limitations between substrates and products, enabling the immobilization and efficient utilization of inert C(sp) catalysts under mild conditions. 3 The activation activity and efficiency of the H-H bond have significantly surpassed those of traditional 3D coordination polymers. Based on the high tunability of coordination polymer design, strategically reducing dimensionality can further improve catalyst dispersibility and accessibility of active sites, thereby alleviating mass transfer limitations in industrial conversion and increasing catalytic flux.

[0003] By further reducing the dimension of coordination polymers to single strands or a few strands, one-dimensional (1D) coordination polymer nanowires have emerged as a novel one-dimensional functional material. Compared with 3D bulk or 2D nanosheets, 1D ultrafine nanowires possess more easily exposed active sites, excellent flexibility, and faster mass diffusion capabilities, making them ideal candidate systems for highly active catalysts. Although some one-dimensional ultrafine coordination polymer nanowires for specific applications such as molecular electronics, polarized luminescence, photoluminescence, and photoelectric conversion have been reported, 1D ultrafine polymer nanowires suitable for heterogeneous catalysis have not yet been developed. Among existing preparation methods, in-situ exfoliation of three-dimensional chain-like coordination polymers, utilizing various external forces to disrupt the weak van der Waals interactions between chains, remains the most direct and effective strategy for obtaining 1D nanowires. However, the known types of 3D chain-like coordination polymers are still limited, which severely restricts their widespread application. This bottleneck stems from a key challenge: how to maintain the high activity of the molecular catalyst within the three-dimensional chain structure while constructing it. In particular, reducing the nanowire diameter to the sub-1 nanometer level is expected to bring the active site exposure rate close to 100% and significantly shorten the diffusion path of ions and electrons. This is a more challenging and significant goal for improving the activity of heterogeneous catalysts. In many chemical transformations, the use of inert C(sp...) 3 Direct activation and functionalization of C(sp)-H bonds into high-value-added products remains one of the most challenging topics, stemming from the fact that C(sp)-H bonds are difficult to activate directly. 3 The inherent strong inertness of the )−H bond. Related reports have utilized the photoexcited multistate of the empty valence shell in high-valence transition metal coordination compounds to release highly reactive hydrogen atom transfer (HAT) reagents via photoinduced ligand-metal charge transfer (LMCT), enabling the targeted capture of C(sp) atoms from the substrate. 3 The formation of the corresponding alkyl radical by )−H is the realization of C(sp 3 )−H is an efficient means of activating functionalization. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, the present invention aims to provide a method for preparing coordination polymer nanowires that catalyze CH bond functionalization and their applications. Three-dimensional chain-like coordination polymers are constructed using anion-terminated low-coordination-number metal ions and electropositive organic ligands as building blocks. This not only maintains the activity of the metal catalyst and the functional organic ligands but also overcomes the weak electrostatic interactions between chains using ultrasonic liquid-phase exfoliation technology to prepare ultrafine one-dimensional coordination polymer nanowires. Under photoexcitation, the ultrafine nanowire materials can efficiently and selectively catalyze the activation and functionalization reaction of inert CH bonds.

[0005] To achieve the above objectives and solve the problems existing in the prior art, the technical solution adopted by the present invention is: a coordination polymer nanowire, using low coordination number transition metal ions Cu 2+Using electropositive L as a ligand, three-dimensional chain-like polymer nanowires were constructed via a solvothermal synthesis strategy. Subsequently, highly catalytically active coordination polymer nanowires were efficiently prepared using solvent-assisted ultrasonic exfoliation. The synthetic route is as follows: The synthesis route for Cu-PCQ is as follows: Cu 2+ +H2PCQ→Cu-PCQ; The ligand L is selected from H2PCQ; The transition metal salt is selected from either copper chloride or copper chloride dihydrate; The ligand H2PCQ has the following molecular structure (A).

[0006] The preparation method includes the following steps: Step 1: Add p-dibromobenzyl and methyl quinoline-3-carboxylate to 20-40 mL of acetonitrile at a molar ratio of 1:2.2-2.6. Heat the solution under reflux and stir for 18-20 h. After cooling to room temperature, centrifuge to remove the solution, collect the white powder, and dry it in a vacuum oven.

[0007] Step 2: Add the above white powder to concentrated hydrochloric acid (12 M) at a molar ratio of 1:70~75. Heat the reaction mixture under reflux and stir for 45~50 hours. After cooling to room temperature, remove the solution by filtration, and wash the precipitate 3~5 times each with deionized water and ethanol. Dry the solid in a vacuum oven at 60~70 degrees Celsius to obtain white solid H2PCQ.

[0008] Step 3: Ligand H2Q and copper chloride dihydrate are dissolved in a molar ratio of 1:3.8~4 in a mixed solvent of N,N-dimethylformamide (DMF) and acetonitrile with a volume ratio of 1:3~3.2. The mixture is heated to 120~125 degrees Celsius in a forced-air drying oven and cooled to room temperature to precipitate a green solid, thus obtaining the target compound Cu-PCQ.

[0009] Step 4: Disperse Cu-PCQ in one of carbon tetrachloride, dichloromethane, ethanol, acetonitrile, and methanol, with a Cu-PCQ to organic solvent ratio of 15 mg~20 mg: 1.5 ml. Sonicate the mixture at room temperature for 6~10 hours. Filter the green suspension and dry it under vacuum at 70~80℃ to obtain Cu-PCQ-NW nanowires.

[0010] The coordination polymer nanowires prepared by the method can be used in the coupling reaction of cyclohexane with benzenemethylene malononitrile, the coupling reaction of cyclohexane with sodium benzenesulfonate, and the aerobic oxidation reaction of ethylbenzene.

[0011] The beneficial effects of this invention are: a method for preparing coordination polymer nanowires and their application, wherein the coordination polymer nanowires utilize Cu in transition metal salts. 2+ Using L as a ligand, coordination polymer materials are prepared via a solvothermal reaction, followed by physical exfoliation to obtain ultrafine coordination polymer nanowires. These ultrafine nanowires expose more active sites, significantly improving electron transfer efficiency and reducing substrate diffusion effects. This allows inert cyclohexane to undergo alkylation with benzenemethylene malononitrile or thioetherification with sodium benzenesulfonate under mild conditions via LMCT and HAT processes. Furthermore, highly dispersed PCQ ligands, under photoexcitation, convert oxygen into reactive oxygen species that can combine with alkyl radicals generated in the HAT process, achieving the carbonylation of ethylbenzene with excellent yield and selectivity. Compared to existing technologies, the coordination polymer nanowires prepared using this method have low raw material costs, high yields, and chemically stable compounds, making them easy to apply in practice. Moreover, they can efficiently catalyze the coupling reaction of cyclohexane with benzenemethylene malononitrile or sodium benzenesulfonate and the aerobic oxidation of ethylbenzene under mild light conditions. Attached Figure Description

[0012] Figure 1 This is a crystal structure diagram of Cu-PCQ, the target compound in Example 3 of this invention.

[0013] Figure 2 These are infrared images of the target compounds Cu-PCQ and Cu-PCQ-NW from Example 3 of this invention.

[0014] Figure 3 This is a TEM image of Cu-PCQ-NW, the target compound in Example 3 of this invention.

[0015] Figure 4 This is a yield diagram showing the catalytic coupling reaction of cyclohexane with benzenemethylene malononitrile, the coupling reaction of cyclohexane with sodium benzenesulfonate, and the aerobic oxidation reaction of ethylbenzene under light irradiation conditions of the target compound Cu-PCQ-NW in Example 3 of this invention. Detailed Implementation

[0016] The present invention will be further described below with reference to the embodiments. Example 1

[0017] 2.63 g (10.0 mmol) of benzyl dibromo and methyl quinoline-3-carboxylate (4.68 g, 25.0 mmol) were added to a 100 mL round-bottom flask containing 30 mL of acetonitrile. The solution was heated under reflux with stirring for 20 h. After cooling to room temperature, the solution was removed by centrifugation, and the white powder collected was compound 1, which was dried in a vacuum oven. Yield: 4.26 g, 67.0%. 1H NMR (400 MHz, DMSO-d6) δ 10.21 (s, 2H), 9.93 (s, 2H), 8.70 (d, J = 8.2 Hz, 2H), 8.43 (d, J = 8.9 Hz, 2H), 8.27 (d, J = 1.8 Hz, 2H), 8.09 (t, J = 7.6 Hz, 2H), 7.39 (s, 4H), 6.46 (s, 4H), 4.06 (s, 6H). 13 C NMR (126 MHz, DMSO-d6) δ 162.53, 150.79,148.69, 138.41, 137.88, 134.28, 132.46, 130.79, 129.19, 127.83, 124.32,119.50, 59.69, 53.44. ESI-MS: calcd for C 30 H 26 N2O4 2+ : 239.0941; Found for [M] 2+ 239.0940. Compound 1 (4.26 g, 6.7 mmol) was added to a 100 mL flask, followed by 40 mL of concentrated hydrochloric acid (12 mol / L). The reaction mixture was heated under reflux and stirred for 48 hours. After cooling to room temperature, the solution was removed by filtration, and the precipitate was washed three times each with deionized water and ethanol. The solid was dried in a vacuum oven at 60 °C to give a white solid, H₂PCQ. Yield: 1.39 g (40%). 1 H NMR (400 MHz, DMSO-d6) δ 10.16 (s, 2H), 9.88 (s, 2H), 8.69 (d, J = 8.2 Hz, 2H), 8.44 (d, J = 9.0 Hz, 2H), 8.26 (t, J = 8.0 Hz, 2H), 8.07 (t, J = 7.7 Hz, 2H), 7.40 (s, 4H), 6.47 (s, 4H). ESI-MS:calcd for C 28 H 22 N2O4 2+ : 225.0785; Found for [M]2+ : 225.0786. Example 2

[0018] Ligand H₂PCQ (0.01 mmol) and copper chloride dihydrate (0.04 mmol) were dissolved in a mixed solvent of N,N-dimethylformamide (DMF) and acetonitrile (v₁:v₂ = 1:3, total 4 mL). The solution was dissolved by sonication, and the resulting solution was added to a glass vial. The vial was placed in a high-pressure reactor lined with 15 mL of polytetrafluoroethylene and reacted at 120 °C for 45 h. After cooling to room temperature, green blocky crystals were separated, washed with acetonitrile, and dried. The yield was approximately 40% (based on vacuum-dried crystals). The crystal structure of the green crystals was obtained by X-ray single-crystal diffraction analysis. Figure 1 . Example 3

[0019] Freshly prepared Cu-PCQ (15 mg) was dispersed in carbon tetrachloride (1.5 mL) and sonicated for 8 hours at room temperature. The green suspension was filtered and dried overnight under vacuum at 80°C to obtain Cu-PCQ-NW single chains. Figure 3 As shown. (Through) Figure 2 and 3 It can be seen that the expected single-chain nanowires were successfully obtained through the exfoliation technique. Example 4

[0020] Freshly prepared Cu-PCQ (15 mg) was dispersed in dichloromethane (1.5 mL) and sonicated for 8 hours at room temperature. The green suspension was filtered and dried overnight under vacuum at 80°C to obtain Cu-PCQ-NW single chains. Example 5

[0021] Freshly prepared Cu-PCQ (15 mg) was dispersed in ethanol (1.5 mL) and sonicated at room temperature for 8 hours. The green suspension was filtered and dried overnight under vacuum at 80°C to obtain Cu-PCQ-NW single chains. Example 6

[0022] Freshly prepared Cu-PCQ (15 mg) was dispersed in acetonitrile (1.5 mL) and sonicated at room temperature for 8 hours. The green suspension was filtered and dried overnight under vacuum at 80°C to obtain Cu-PCQ-NW single chains. Example 7

[0023] Freshly prepared Cu-PCQ (15 mg) was dispersed in methanol (1.5 mL) and sonicated at room temperature for 8 hours. The green suspension was filtered and dried overnight under vacuum at 80°C to obtain Cu-PCQ-NW single chains.

[0024] Example 8: Coupling reaction of cyclohexane and benzenemethylene malononitrile catalyzed by Cu-PCQ-NW

[0025] In a 10 mL flame-dried Schlenk quartz flask, 5 mg of Cu-PCQ-NW prepared in Example 3, 10.5 μmol tetrabutylammonium chloride, 0.1 mmol benzenemethylmalononitrile, and 1 mmol cyclohexane were added to 2 mL of acetonitrile. Under nitrogen protection, the mixture was stirred at room temperature and irradiated with a 455 nm LED for 12 hours. After the specified time, the mixture was centrifuged at 6000 rpm for 5 minutes, and the supernatant was concentrated by vacuum distillation. The concentrated product was separated by silica gel column chromatography (using ethyl acetate / petroleum ether as eluent) to obtain the separation yield. The results showed that the conversion of benzenemethylmalononitrile to 2-(cyclohexylphenylmethyl)malononitrile was 80%, as shown in the figure. Figure 4 As shown.

[0026] Example 9: Coupling reaction of cyclohexane and benzenemethylene malononitrile catalyzed by Cu-PCQ-NW

[0027] In a 10 mL flame-dried Schlenk quartz flask, 5 mg of Cu-PCQ-NW prepared in Example 3, 10.5 μmol ammonium chloride, 0.2 mmol sodium benzenesulfinate, 0.3 mmol acetyl chloride, and 1 mmol cyclohexane were added to 2 mL of acetonitrile. Under nitrogen protection, the mixture was stirred at room temperature and irradiated with a 455 nm LED for 10 hours. After the specified time, the mixture was centrifuged at 6000 rpm for 5 minutes, and the supernatant was concentrated by vacuum distillation. The concentrated product was separated by silica gel column chromatography (using ethyl acetate / petroleum ether as eluent) to obtain the separation yield. The results showed that the conversion of sodium benzenesulfinate to cyclohexylphenyl sulfide was 81%, as shown in the figure. Figure 4 As shown.

[0028] Example 10: Aerobic oxidation of ethylbenzene catalyzed by Cu-PCQ-NW

[0029] In a 10 mL flame-dried Schlenk quartz flask, 5 mg of Cu-PCQ-NW prepared in Example 3, 10.5 μmol tetrabutylammonium chloride, and 0.1 mmol ethylbenzene were added to 1 mL of acetonitrile. The resulting mixture was stirred and irradiated with a 455 nm LED for 10 hours under an oxygen atmosphere. After the specified time, the mixture was centrifuged at 6000 rpm for 5 minutes, and the supernatant was concentrated by vacuum distillation. The concentrated product was then separated by silica gel column chromatography (using ethyl acetate / petroleum ether as eluent) to obtain the separation yield. The results showed that the conversion of ethylbenzene to acetophenone was 90%. Figure 4 As shown.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coordination polymer nanowire, characterized in that, The following steps were used to prepare the three-dimensional chain metal-organic framework material Cu-PCQ, which was newly prepared by inorganic copper salt and coordination L through a solvothermal method, was dispersed in an organic solvent and ultrasonically sonicated to obtain a colloidal suspension. After centrifugation or filtration and drying, coordination polymer nanowires Cu-PCQ-NW were obtained. The inorganic copper salt is selected from either copper chloride or copper chloride dihydrate; The ligand L is selected from H2PCQ, which has a structural formula as shown in (A); ； The synthesis route for Cu-PCQ is as follows: With 2+ +H2PCQ→Cu-PCQ.

2. The coordination polymer nanowire according to claim 1, characterized in that: The organic solvent is selected from at least one of carbon tetrachloride, dichloromethane, ethanol, acetonitrile and methanol, and the ratio of Cu-PCQ to organic solvent is 15 mg to 20 mg: 1.5 ml.

3. The coordination polymer nanowire according to claim 1, characterized in that: The ultrasound time is 6-10 hours.

4. The coordination polymer nanowire according to claim 1, characterized in that, The preparation method of ligand H2PCQ includes the following steps: (1) Add p-dibromobenzyl and methyl quinoline-3-carboxylate to 20-40 mL of acetonitrile at a molar ratio of 1:2.2-2.6; heat the solution under reflux and stir for 18-20 h, then cool, centrifuge, and dry. (2) The above white powder was added to 12 M concentrated hydrochloric acid at a molar ratio of 1:70~75; the reaction mixture was heated under reflux and stirred for 45~50 hours; cooled, filtered, washed and dried to obtain white solid H2PCQ.

5. The coordination polymer nanowire according to claim 4, characterized in that, The preparation method of Cu-PCQ is as follows: The ligand H2PCQ and the inorganic copper salt were dissolved in a mixed solvent at a molar ratio of 1:3.8~4, and the volume ratio of N,N-dimethylformamide to acetonitrile in the mixed solvent was 1:3~3.

2. The target compound Cu-PCQ was obtained by heating the product to 120-125 degrees Celsius in a forced-air drying oven and then cooling it to room temperature to precipitate a solid.

6. The coordination polymer nanowire according to claim 5, characterized in that, The preparation method of the coordination polymer nanowires Cu-PCQ-NW is as follows: Cu-PCQ was dispersed in an organic solvent at a ratio of 15 mg to 20 mg to 1.5 ml, and sonicated at room temperature for 6 to 10 hours. The mixture was then filtered and dried to obtain Cu-PCQ-NW nanowires.

7. The application of the coordination polymer nanowires according to any one of claims 1-6 in the catalytic coupling reaction of cyclohexane and benzenemethylene malononitrile.

8. The application of the coordination polymer nanowires according to any one of claims 1-6 in the catalytic coupling reaction of cyclohexane and sodium benzenesulfinate.

9. The application of the coordination polymer nanowires according to any one of claims 1-6 in the catalytic aerobic oxidation reaction of ethylbenzene.

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