Preparation method of an iron-based supramolecular catalyst

Abstract

This invention discloses a novel iron-based supramolecular catalyst and its preparation method. A fluoroboron pyrrole (Bodipy) organic photosensitizer with strong visible light absorption and a long excited-state lifetime is covalently coupled to an inexpensive iron-based tetrapyridine catalyst via a click reaction, shortening the distance between the photosensitizer and the catalyst to construct a non-precious metal supramolecular photocatalytic system with strong visible light absorption. Using 1,3-dimethylbenzimidazole as a sacrificial agent, the catalyst exhibits high catalytic activity and selectivity in photocatalytic carbon dioxide reduction. The reaction system is low-cost and has promising application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of photocatalysis, and in particular to a method for preparing an iron-based supramolecular photocatalyst. Background Art

[0002] The continuous release of carbon dioxide (CO2) into the atmosphere due to human activities has led to rising global temperatures and severe environmental problems. Therefore, developing photocatalytic systems that utilize sunlight to efficiently and selectively reduce CO2 to small fuel molecules is an effective way to reduce reliance on fossil energy and alleviate environmental pollution. In traditional catalytic systems, photosensitizers and catalysts exist in free form in solution, and electron transfer between components is limited by diffusion and collision processes, resulting in low electron transfer efficiency. Furthermore, traditional catalytic systems generally rely on precious metal photosensitizers or catalysts, which is not conducive to large-scale application.

[0003] Based on the above situation, the present invention provides a new iron-based supramolecular catalyst, which covalently couples the fluoroboropyrrole (Bodipy=BDP) organic photosensitizer with strong visible light absorption and long excited state lifetime with the inexpensive iron-based tetrapyridine catalyst through the Click reaction, shortens the distance between the photosensitizer and the catalyst, and constructs a non-precious metal supramolecular photocatalytic system with strong visible light absorption ability. The system has strong visible light absorption ability and long excited state lifetime, which is conducive to the intramolecular / intermolecular electron transfer process and efficient solar energy utilization, thereby significantly improving the photosynthesis efficiency. It is used in the visible light-driven carbon dioxide reduction reaction, and carbon dioxide is successfully reduced to carbon monoxide. This work provides an important scientific reference for the development of efficient and inexpensive non-precious metal molecular devices. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a novel iron-based supramolecular photocatalyst and a preparation method thereof, and the catalyst can realize photocatalytic carbon dioxide reduction.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for preparing an iron-based supramolecular catalyst comprises the following steps:

[0007] Step a: adding 9-bromo-10-formylanthracene, 2,4-dimethylpyrrole, trifluoroacetic acid, 2,3-dichloro-5,6-dicyanobenzoquinone, triethylamine and boron trifluoride etherate to an organic solvent to react to generate compound 1;

[0008] wherein the molar ratio of 9-bromo-10-formylanthracene, 2,4-dimethylpyrrole, 2,3-dichloro-5,6-dicyanobenzoquinone, triethylamine and boron trifluoride etherate is 1.5-1.0:4-4.5:1.5-2.0:0.01-0.03:0.02-0.03;

[0009] Step b: adding 4-hydroxyphenylboronic acid pinacol ester, 1,3-dibromoethane and anhydrous potassium carbonate to an organic solvent to obtain compound 2 through reaction;

[0010] wherein the molar ratio of 4-hydroxyphenylboronic acid pinacol ester, 1,3-dibromoethane and anhydrous potassium carbonate is 0.5-1.2:4.5-5.5:4.5-5.5;

[0011] Step c: dissolving compound 2 in an organic solvent, adding sodium azide, and reacting to generate compound 3;

[0012] The molar ratio of compound 2 to sodium azide is 0.5-1.2:1.0-1.5;

[0013] Step d: dissolving compound 1, compound 3, anhydrous potassium carbonate and Pd(PPh3)4 in an organic solvent to react to generate compound 4;

[0014] The molar ratio of compound 1, compound 3, anhydrous potassium carbonate and Pd(PPh3)4 is 0.05-0.15:0.05-0.15:0.5-1.0:0.002-0.01;

[0015] Step e: dissolving 2-phenoxyethyl bromide in an organic solvent, adding sodium azide, and reacting to generate compound 5;

[0016] The molar ratio of 2-phenoxyethyl bromide to sodium azide is 0.05-0.15:1.0-1.5;

[0017] Step f: dissolving anhydrous potassium carbonate and 4-hydroxybenzaldehyde in an organic solvent, adding propynyl bromide, and reacting to generate compound 6;

[0018] wherein the molar ratio of anhydrous potassium carbonate, 4-hydroxybenzaldehyde and propynyl bromide is 10-15:8-12:9-13;

[0019] Step j: dissolving compound 6 and piperidine in an organic solvent, adding 1,2-butanedione, and reacting to generate compound 7;

[0020] wherein the molar ratio of compound 6, piperidine and 1,2-butanedione is 18-22:1-3:8-12;

[0021] Step h: dissolving 1-(2-oxo-2-(pyridin-2-yl)ethyl)pyridin-1-ium iodide, compound 6, and anhydrous ammonium acetate in an organic solvent to react to generate compound 8;

[0022] wherein the molar ratio of 1-(2-oxo-2-(pyridin-2-yl)ethyl)pyridin-1-ium iodide, compound 6, and anhydrous ammonium acetate is 3.0-3.5:0.5-1.2:100-105;

[0023] Step i: Compound 4 and Compound 8 are dissolved in an organic solvent, and sodium ascorbate and copper sulfate hydrate are added to react to generate Compound 9 and Compound 10;

[0024] wherein the molar ratio of compound 4, compound 8, sodium ascorbate and copper sulfate hydrate is 0.05-0.12:0.03-0.04:0.05-0.12:0.03-0.06;

[0025] Step g: Compound 9 and ferrous perchlorate hydrate are dissolved in water to react to form a novel iron-based supramolecular catalyst Fe-2BDP, the chemical structure of which is:

[0026]

[0027] The molar ratio of the compound 9 to ferrous perchlorate hydrate is 0.03-0.06:0.03-0.06;

[0028] Step k: dissolving compound 5 and compound 10 in an organic solution, adding sodium ascorbate and copper sulfate hydrate to react to generate compound 11;

[0029] wherein the molar ratio of compound 5, compound 10, sodium ascorbate and copper sulfate hydrate is 0.05-0.12:0.03-0.04:0.05-0.12:0.03-0.06;

[0030] Step 1: Compound 11 and ferrous perchlorate hydrate are dissolved in water to react to form a novel iron-based supramolecular catalyst Fe-BDP, whose chemical structure is:

[0031]

[0032] The molar ratio of the compound 11 to ferrous perchlorate hydrate is 0.03-0.06:0.03-0.06;

[0033] As a preferred technical solution of the present invention, step a is specifically performed as follows: Under an argon atmosphere, dissolve 9-bromo-10-formylanthracene in 100-200 mL of dehydrated dichloromethane and stir under argon for 10-20 minutes. Add 2,4-dimethylpyrrole while shielding from light and stir for 10-20 minutes. Add trifluoroacetic acid while cooling in an ice bath until the solution turns deep red. Reaction is carried out at 20-30°C for 6-8 hours. Add 2,3-dichloro-5,6-dicyanobenzoquinone and continue stirring for 10-20 minutes. Add 3-5 mL of triethylamine and 3-5 mL of boron trifluoride etherate while cooling in an ice bath. Stir the reaction solution at 20-30°C for 6-8 hours. Stop the reaction, add saturated brine to the solution, extract with dichloromethane, separate the organic phase, and dry it over anhydrous sodium sulfate. Remove the solvent under reduced pressure, redissolve the solution in dichloromethane, and separate by column chromatography to obtain Compound 1.

[0034] As a preferred technical solution of the present invention, the specific operation of step b is: dissolving 4-hydroxyphenyl borate, 1,2-dibromoethane and anhydrous potassium carbonate in 15-30 mL of acetonitrile, passing argon at room temperature for 10-30 minutes, and placing in an oil bath at 60-80°C for reaction for 20-26 hours; after the reaction is stopped, the reaction solution is cooled to room temperature and filtered to remove insoluble matter; after the solvent is removed under reduced pressure, it is redissolved with dichloromethane organic solvent and washed twice with saturated sodium chloride solution; after the solvent is removed under reduced pressure, it is redissolved with dichloromethane and ethyl acetate organic solvents, and separated by column chromatography to obtain compound 2.

[0035] As a preferred technical solution of the present invention, the specific operation of step c is: dissolving compound 2 in 8-12 mL of N,N-dimethylformamide, stirring under argon conditions for 10-20 minutes, adding sodium azide to the solution; placing it in an oil bath at 80-120°C for 1-2 hours; cooling the reaction mixture to 30-50°C, adding saturated brine, extracting with toluene, separating the organic phase, drying the organic phase with anhydrous sodium sulfate, and then taking the organic layer and concentrating under reduced pressure to obtain compound 3.

[0036] As a preferred technical solution of the present invention, the specific operation of step d is: dissolving compound 1 in 3-5 mL of toluene and dissolving compound 3 in 1-3 mL of ethanol; then adding the above solution to 3-5 mL of water dissolved in anhydrous potassium carbonate, and after 20-30 minutes under argon conditions, adding Pd(PPh3)4, and placing it in an oil bath pot at 80-110°C to react for 6-8 hours; after cooling the reaction mixture to room temperature, adding saturated brine, extracting with dichloromethane, separating the organic phase, and drying the organic phase with anhydrous sodium sulfate. The organic layer is evaporated to obtain a crude product, which is separated by column chromatography to obtain compound 4.

[0037] As a preferred technical solution of the present invention, the specific operation of step e is: dissolving 2-phenoxyethyl bromide in 8-12 mL of N,N-dimethylformamide and stirring under argon for 15-20 minutes; adding sodium azide to the solution and placing it in an oil bath at 80-120°C for 1-2 hours; cooling the reaction mixture to 30-50°C and adding saturated brine, extracting with toluene, separating the organic phase, drying the organic phase with anhydrous sodium sulfate, and then taking the organic layer and concentrating under reduced pressure to obtain compound 5.

[0038] As a preferred technical solution of the present invention, step f is specifically performed as follows: dissolving anhydrous potassium carbonate and 4-hydroxybenzaldehyde in 8-12 mL of N,N-dimethylformamide and stirring under argon for 15-20 minutes; adding bromopropynyl and reacting at room temperature for 10-14 hours; diluting the mixture with cold water after the reaction, extracting the mixture with ethyl acetate, separating the organic phase, drying the organic phase with anhydrous sodium sulfate, and removing the solvent by rotary evaporation under reduced pressure to obtain a crude product. Recrystallization from chloroform and n-hexane yields compound 6.

[0039] As a preferred technical solution of the present invention, the specific operation of step j is: adding compound 6 and piperidine to 4-6 mL of anhydrous methanol; adding the anhydrous methanol solution of 1,2-butanedione dropwise to the above mixed solution through a constant pressure dropping funnel, and the dropping process lasts for 30-20 minutes; reacting in an oil bath at 50-70°C for 6-8 hours; after the reaction is completed, cooling to room temperature, filtering the precipitated solid, and then washing with anhydrous methanol and diethyl ether to obtain compound 7.

[0040] As a preferred technical solution of the present invention, the specific operation of step h is: dissolving 1-(2-oxo-2-(pyridin-2-yl)ethyl)pyridin-1-ium iodide, compound 7 and anhydrous ammonium acetate in 35-45 mL of anhydrous ethanol; under argon conditions, placing in an oil bath at 50-70°C for 20-28 hours; after the reaction, the solution is cooled to room temperature, filtered under reduced pressure, washed with water, anhydrous ethanol and ether in sequence, and vacuum dried to obtain compound 8.

[0041] As a preferred technical solution of the present invention, the specific operation of step i is: dissolving compound 4 and compound 8 in 30-50 mL of a mixed organic solvent of chloroform, ethanol and water, passing argon into the reaction solution for 10-20 minutes, adding sodium ascorbate and copper sulfate hydrate, and reacting at room temperature for 20-26 hours; adding saturated brine to the mixed solution, then extracting with dichloromethane, separating the organic phase, and drying the organic phase with anhydrous sodium sulfate. The organic layer was rotary evaporated to remove the solvent, and separated by column chromatography to obtain compound 9 and compound 10.

[0042] As a preferred technical solution of the present invention, the specific operation of step g is as follows: dissolving compound 9 and ferrous perchlorate hydrate in 30-50 mL of water, stirring under argon for 10-30 minutes, and reacting in an oil bath at 100-120°C for 20-28 hours; after the reaction is stopped, the mixture is allowed to cool to room temperature, spin-dried under reduced pressure, and recrystallized from acetonitrile and diethyl ether. Filter under reduced pressure, wash with pure water, dichloromethane, and diethyl ether, and vacuum dry to obtain the target product, Fe-2BDP.

[0043] As a preferred technical solution of the present invention, the specific operation of step k is: dissolving compound 10 and compound 5 in a mixed organic solvent solution of chloroform, ethanol and water, stirring for 10 to 30 minutes under an argon atmosphere, adding sodium ascorbate and copper sulfate hydrate, and reacting at room temperature for 20 to 26 hours; adding saturated salt water to the reaction solution, and then extracting with dichloromethane, separating the organic phase, and drying the organic phase with anhydrous sodium sulfate. The organic layer solvent is removed by rotary evaporator, and then column chromatography is separated to obtain compound 11.

[0044] As a preferred technical solution of the present invention, the specific operation of step 1 is as follows: Compound 11 and ferrous perchlorate hydrate are dissolved in 30-50 mL of water, stirred under an argon atmosphere for 10-30 minutes, and reacted in an oil bath at 100-120°C for 20-28 hours. After the reaction is terminated, the mixture is allowed to cool to room temperature, and the mixed liquid is spin-dried under reduced pressure and recrystallized from acetonitrile and diethyl ether. The mixture is filtered under reduced pressure, washed with pure water, dichloromethane, and diethyl ether, and vacuum dried to obtain the target product, Fe-BDP.

[0045] The present invention also proposes the use of a novel iron-based supramolecular catalyst for photocatalytic carbon dioxide reduction. In specific applications, the photocatalytic system includes a light source, a catalyst, a sacrificial agent, and a solvent. The catalyst is the aforementioned iron-based supramolecular catalyst, Fe-BDP or Fe-2BDP, the sacrificial agent is preferably 1,3-dimethylbenzimidazole, and the solvent is preferably a mixed solution of water, acetonitrile, and N,N-dimethylformamide. In the photocatalytic system, the catalyst concentration is preferably 10 μM, and the sacrificial agent concentration is preferably 0.02 M.

[0046] In summary, compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] 1. The iron-based supramolecular catalyst prepared by the present invention abandons precious metals such as ruthenium, rhodium, and platinum, and uses non-precious metal iron, thereby reducing production costs.

[0048] 2. The iron-based supramolecular catalyst prepared by the present invention covalently couples the Bodipy organic photosensitizer with strong visible light absorption and long excited state lifetime with the inexpensive iron-based tetrapyridine catalyst through a Click reaction, which shortens the distance between the photosensitizer and the catalyst, facilitates the intramolecular / intermolecular electron transfer process, and significantly improves the photocatalytic CO2 reduction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a synthesis process roadmap of the iron-based supramolecular catalyst Fe-BDP and the iron-based supramolecular catalyst Fe-2BDP in Example 1 of the present invention.

[0050] Figure 2-1 The iron-based supramolecular catalyst Fe-BDP prepared in Example 1 of the present invention is 1 H NMR spectrum.

[0051] Figure 2-2 The iron-based supramolecular catalyst Fe-2BDP prepared in Example 1 of the present invention 1 H NMR spectrum.

[0052] Figure 3-1 It is the mass spectrum of the iron-based supramolecular catalyst Fe-BDP prepared in Example 1 of the present invention.

[0053] Figure 3-2 It is a mass spectrum of the iron-based supramolecular catalyst Fe-2BDP prepared in Example 1 of the present invention.

[0054] Figure 4 It is a UV-visible absorption spectrum of the iron-based supramolecular catalysts Fe-BDP and Fe-2BDP prepared in Example 1 of the present invention in N,N-dimethylformamide.

[0055] Figure 5 It is a fluorescence emission spectrum of the iron-based supramolecular catalysts Fe-BDP and Fe-2BDP prepared in Example 1 of the present invention in N,N-dimethylformamide. DETAILED DESCRIPTION

[0056] The present invention is further described in detail below through specific examples. Unless otherwise specified, the raw materials used in the examples can be obtained from conventional commercial sources.

[0057] Example 1

[0058] The present invention provides an iron-based supramolecular catalyst, and its preparation method is described as follows:

[0059] 1. Synthesis of compound 1, the reaction formula is:

[0060]

[0061] Under an argon atmosphere, 150 mL of anhydrous dichloromethane was added to a dry 500 mL three-necked flask. 1.8 mmol of 9-bromo-10-formylanthracene was added to the flask and purged with argon for 20 minutes. While shielding from light, 4.4 mmol of 2,4-dimethylpyrrole was added to the solution and stirred for 15 minutes. Trifluoroacetic acid was added dropwise to the solution using a syringe in an ice bath until the solution turned deep red. The reaction mixture was stirred continuously at room temperature for 6 hours, and the reaction progress was monitored by TLC. 1.8 mmol of 2,3-dichloro-5,6-dicyanobenzoquinone was then added to the solution and stirred for 15 minutes. 3.2 mL of triethylamine and 3.2 mL of boron trifluoride etherate were added using a syringe in an ice bath and stirred at room temperature for 6 hours. The solvent was removed by rotary evaporation, and the residue was purified by chromatography with dichloromethane / n-hexane = 1 / 1, v / v as eluent to obtain compound 1 (250.0 mg, 28.3%) as an orange-red solid.

[0062] Proton spectrum of compound 1 1 H NMR (400MHz, CDCl3) δ7.96 (d, J=8.5Hz, 2H), 7.72 (d, J=8.5Hz, 2H), 7.50–7.31 (m, 6H), 7.17 (d, J= 8.3Hz,2H),5.92(s,2H),4.32(t,J=4.7Hz,2H),3.72(t,J=4.7Hz,2H),2.64(s,6H),0.74(s,6H).

[0063] 2. Synthesis of compound 2, the reaction formula is:

[0064]

[0065] 1.0 mmol of 4-hydroxyphenylboronic acid ester, 1.0 mmol of 1,2-dibromoethane and 5.0 mmol of anhydrous potassium carbonate were mixed in 20 mL of acetonitrile. Under an argon atmosphere, the mixture was reacted at 70 ° C for 24 hours. After cooling to room temperature, the reaction mixture was filtered, and the residue was washed with dichloromethane, and then the filtrate was concentrated under reduced pressure. The residue was dissolved with 50 mL of dichloromethane and washed twice with saturated sodium chloride solution. The organic phase was concentrated under reduced pressure. The crude product was purified by silica gel column chromatography with petroleum ether / ethyl acetate = 20 / 1, v / v as eluent to give compound 2 (261.6 mg, 80.0%) as a white powder.

[0066] Proton spectrum of compound 2 1H NMR (400MHz, CDCl3) δ7.75 (d, J = 8.4Hz, 2H), 6.90 (d, J = 8.5Hz, 2H), 4.31 (t, J = 6.4Hz, 2H), 3.64 (t, J = 6.4Hz, 2H), 1.33 (s, 12H).

[0067] 3. Synthesis of compound 3, the reaction formula is:

[0068]

[0069] Under an argon atmosphere, 1.0 mmol of compound 2 was dissolved in 10 mL of N,N-dimethylformamide. 1.2 mmol of sodium azide was added to the solution, and the mixture was stirred at 100°C for 1 hour. After the reaction was complete, saturated brine was added, and the mixture was extracted with toluene. The organic phase was separated, dried over anhydrous sodium sulfate, and then concentrated under reduced pressure to obtain compound 3 (299.0 mg, 97.0%) as a white solid.

[0070] Proton spectrum of compound 3 1 H NMR (400MHz, CDCl3) δ7.76 (d, J = 8.3 Hz, 2H), 6.91 (d, J = 8.3 Hz, 2H), 4.18 (t, J = 5.0 Hz, 2H), 3.60 (t, J = 5.0 Hz, 2H), 1.33 (s, 12H).

[0071] 4. Synthesis of compound 4, the reaction formula is:

[0072]

[0073] 0.1 mmol of compound 1 was dissolved in 4 mL of toluene, and 0.1 mmol of compound 3 was dissolved in 2 mL of ethanol. The above solution was then mixed with 4 mL of an aqueous solution containing 0.6 mmol of anhydrous potassium carbonate. After argon bubbling for 30 min, 0.005 mmol of Pd(PPh3)4 was added and stirred at 96 ° C for 6 hours. After cooling to room temperature, saturated brine was added, extracted with dichloromethane, and the organic phase was separated. The organic phase was dried over anhydrous sodium sulfate and then rotary evaporated to remove the solvent to obtain a crude product, which was purified by chromatography on a silica gel column with an eluent of n-hexane / dichloromethane = 1 / 1, v / v to obtain a red solid compound 4 (0.16 g, 95.9%).

[0074] Proton spectrum of compound 4 1H NMR (400MHz, CDCl3) δ7.96 (d, J=8.5Hz, 2H), 7.72 (d, J=8.5Hz, 2H), 7.50–7.31 (m, 6H), 7.17 (d, J= 8.3Hz,2H),5.92(s,2H),4.32(t,J=4.7Hz,2H),3.72(t,J=4.7Hz,2H),2.64(s,6H),0.74(s,6H).

[0075] 5. Synthesis of compound 5, the reaction formula is:

[0076]

[0077] Under an argon atmosphere, 1.0 mmol of 2-phenoxyethyl bromide was dissolved in 10 mL of N,N-dimethylformamide. 1.2 mmol of sodium azide was added to the solution, followed by stirring at 100°C for 1 hour. After completion of the reaction, saturated brine was added, and the mixture was extracted with toluene. The organic phase was separated, dried over anhydrous sodium sulfate, and then concentrated under reduced pressure to yield Compound 5 (196.4 mg, 97.0%) as a white solid.

[0078] Proton spectrum of compound 5 1 HNMR (400MHz, CDCl3) δ7.31(t,J=7.9Hz,2H),7.09–6.85(m,3H),4.30–4.03(m,2H),3.59(t,J=4.9Hz,2H).

[0079] 6. Synthesis of compound 6, the reaction formula is:

[0080]

[0081] 12 mmol of anhydrous potassium carbonate and 10 mmol of 4-hydroxybenzaldehyde were dissolved in 10 mL of N,N-dimethylformamide. After passing argon for 15 minutes, 11 mmol of propynyl bromide was added dropwise to the above mixture at room temperature. After stirring at room temperature for 12 hours, it was diluted with cold water. The organic phase was extracted with ethyl acetate and collected. The organic phase was dried over anhydrous sodium sulfate and then rotary evaporated to remove the solvent to obtain a crude product. Recrystallization from chloroform and n-hexane gave a pale white solid compound 6 (1377.4 mg, 86.0%).

[0082] Proton spectrum of compound 6 1 HNMR (400MHz, CDCl3) δ9.91 (s, 1H), 7.86 (d, J = 8.7Hz, 2H), 7.10 (d, J = 8.7Hz, 2H), 4.79 (d, J = 2.3Hz, 2H), 2.57 (t, J = 2.3Hz, 1H).

[0083] 7. Synthesis of compound 7, the reaction formula is:

[0084]

[0085] Under an argon atmosphere, 20 mmol of compound 6 and 2 mmol of piperidine were dissolved in 5 mL of anhydrous methanol to obtain solution A. 10 mmol of 1,2-butanedione was dissolved in 3 mL of anhydrous methanol and added dropwise to solution A using a constant pressure dropping funnel over 30 minutes. After heating under reflux for 8 hours, the mixture was cooled to room temperature to precipitate solids. The mixture was filtered under reduced pressure and washed with anhydrous methanol and diethyl ether to obtain compound 7 (256.4 mg, 6.9%) as a yellow solid.

[0086] Proton spectrum of compound 7 1 H NMR (400MHz, CDCl3) δ7.82(d,J=16.1Hz,2H),7.63(d,J=8.7Hz,4H),7.36(d,J=1 6.1Hz, 2H), 7.02 (d, J = 8.7Hz, 4H), 4.75 (d, J = 2.2Hz, 4H), 2.56 (t, J = 2.2Hz, 2H).

[0087] 8. The synthesis of compound 8, the reaction formula is:

[0088]

[0089] 3.3 mmol of 1-(2-oxo-2-(pyridin-2-yl)ethyl)pyridin-1-ium iodide, 1.0 mmol of compound 7, and 8 g of anhydrous ammonium acetate were dissolved in 40 mL of anhydrous ethanol. The mixture was deaerated and deoxygenated, then heated under reflux with stirring for 24 hours. After the reaction, the solution was cooled to room temperature, filtered under reduced pressure, and washed sequentially with water, anhydrous ethanol, and diethyl ether to obtain compound 8 (164.2 mg, 28.7%) as an off-white solid.

[0090] Proton spectrum of compound 8 1 H NMR (400MHz, CDCl3) δ8.90(d,J=1.6Hz,2H),8.73(m,6H),7.91(m,6H),7.46–7.30(m,2H),7.20–7.10(m,4H),4.80(d,J=2.4Hz,4H),2.59(m,2H).

[0091] 9. The synthesis of compound 9 and compound 10, the reaction formula is:

[0092]

[0093] 0.09mmol of compound 4 and 0.04mmol of compound 8 were dissolved in 40mL of a mixed solvent of chloroform, ethanol, and water (6 / 1 / 1, v / v / v) to obtain solution A. After passing argon for 15 minutes, 0.09mmol of sodium ascorbate and 0.05mmol of copper sulfate hydrate were added to solution A and stirred at room temperature for 24 hours. Saturated brine was added to the reaction solution, which was then extracted with dichloromethane. The organic phase was separated and dried over anhydrous sodium sulfate, and then the solvent was removed by rotary evaporation to obtain a crude product. The crude product was purified by silica gel column chromatography using an eluent of ethyl acetate / methanol / triethylamine = 20 / 1 / 5, v / v / v, to obtain red solid compounds 9 (20.7mg, 38.4%) and 10 (21.8mg, 40.5%).

[0094] Proton spectrum of compound 9 1 HNMR(400MHz, CDCl3)δ8.88(s,2H),8.77–8.63(m,6H),8.00(s,2H),7.97–7.86(m,10H),7.67(d,J=8.6Hz,4H),7.43–7.29(m,14H),7.2 2(d,J=8.3Hz,4H),7.12(d,J=8.1Hz,4H),5.91(s,4H),5.39(s,4H),4.98–4.86(m,4H),4.60–4.52(m,4H),2.63(s,12H),0.71(s,12H).

[0095] Proton spectrum of compound 10 1 H NMR (400MHz, CDCl3) δ8.90(d,J=7.7Hz,2H),8.79–8.63(m,6H),8.00(s,1H),7.97–7.86(m,8H),7.67(d,J=8.5Hz,2H),7.45–7.29(m,8H),7.23(d ,J=8.4Hz,2H),7.20–7.09(m,4H),5.91(s,2H),5.39(s,2H),4.96–4.89( m,2H),4.81(s,2H),4.56(s,2H),2.64(s,6H),2.59(s,1H),0.71(s,6H).

[0096] 10. Synthesis of Fe-2BDP:

[0097]

[0098] 0.05 mmol of compound 9 and 0.5 mmol of ferrous perchlorate hydrate were dissolved in 40 mL of water and stirred at 120°C for 24 hours. After the reaction was stopped, the mixture was allowed to cool to room temperature and the solvent was removed by rotary evaporation under reduced pressure. Excess organic ligand impurities were then removed by recrystallization from acetonitrile and diethyl ether. After filtration, the excess ferrous perchlorate was removed by washing with pure water, dichloromethane, and diethyl ether. After vacuum drying, a deep red solid Fe-2BDP (32.6 mg, 44.0%) was obtained.

[0099] 10. Synthesis of compound 11, the reaction formula is:

[0100]

[0101] 0.09mmol of compound 10 and 0.04mmol of compound 5 were dissolved in 40mL of a mixed solvent of chloroform, ethanol and water (6 / 1 / 1, v / v / v) to obtain solution A. After passing argon for 15 minutes, 0.09mmol of sodium ascorbate and 0.05mmol of copper sulfate hydrate were added to solution A and stirred at room temperature for 24 hours. Saturated brine was added to the reaction solution, which was then extracted with dichloromethane. The organic phase was separated and dried over anhydrous sodium sulfate, and then the solvent was removed by rotary evaporation to obtain a crude product. The crude product was purified by silica gel column chromatography using an eluent of ethyl acetate / methanol / triethylamine = 20 / 1 / 5, v / v / v, to obtain compound 11 (20.5mg, 34.4%) as a red solid.

[0102] Proton spectrum of compound 11 1 HNMR(400MHz, CDCl3)δ8.90(d,J=9.0Hz,2H),8.80–8.63(m,6H),8.08–7.83(m,10H ),7.73–7.60(m,22H),7.47–7.29(m,8H),7.25–7.20(m,2H),7.20–7.09(m,4H),7.0 3–6.94(m,1H),6.87(d,J=8.0Hz,2H),5.91(s,2H),5.39(s,2H),4.98–4.89(m,2H), 4.85–4.77(m,2H),4.62–4.52(m,2H),4.46–4.34(m,2H),2.64(s,6H),0.72(s,6H).

[0103] 12. The synthesis of Fe-BDP is as follows:

[0104]

[0105] 0.05 mmol of compound 11 and 0.5 mmol of ferrous perchlorate hydrate were dissolved in 40 mL of water and stirred at 120°C for 24 hours. After the reaction was stopped, the mixture was allowed to cool to room temperature. The solvent was removed by rotary evaporation under reduced pressure, and then recrystallized from acetonitrile and diethyl ether to remove excess organic ligand impurities. After filtration, the excess ferrous perchlorate was removed by washing with pure water, dichloromethane, and diethyl ether. After vacuum drying, Fe-BDP (25.6 mg, 42.5%) was obtained as a dark red solid.

[0106] Example 2

[0107] The present invention applies the iron-based supramolecular catalyst Fe-BDP prepared above to the photocatalytic reduction of carbon dioxide to produce carbon monoxide. The specific method is as follows:

[0108] 50 μL of a 1 mM solution of the supramolecular catalyst Fe-BDP in N,N-dimethylformamide and 30 mg of 1,3-dimethylbenzimidazole were added to a 16 mL quartz reaction tube. Subsequently, 2.5 mL of N,N-dimethylformamide, 1.5 mL of acetonitrile, and 1 mL of ultrapure water were added, followed by sealing with a rubber tube and bubbling with carbon dioxide for 15 minutes. The catalytic reaction was then carried out under irradiation with a 300 W xenon lamp (λ ≥ 420 nm). During the reaction, gaseous products were quantitatively analyzed using a gas chromatograph (GC-2014). After 10 hours of reaction, the carbon monoxide yield was 19.8 μmol, with a TON of 396.

[0109] Example 3

[0110] The present invention applies the iron-based supramolecular catalyst Fe-2BDP prepared above to the photocatalytic reduction of carbon dioxide to produce carbon monoxide. The specific method is as follows:

[0111] 50 μL of the supramolecular catalyst Fe-2BDPN, a 1 mM N-dimethylformamide solution, and 30 mg of 1,3-dimethylbenzimidazole were added to a 16 mL quartz reaction tube. Subsequently, 2.5 mL of N,N-dimethylformamide, 1.5 mL of acetonitrile, and 1 mL of ultrapure water were added. After sealing with a rubber tube, carbon dioxide was bubbled through the tube for 15 minutes. The catalytic reaction was then carried out under irradiation with a 300 W xenon lamp (λ ≥ 420 nm). During the reaction, gaseous products were quantitatively analyzed using a gas chromatograph (GC-2014). After 10 hours of reaction, the carbon monoxide yield was 23.3 μmol, and the TON of carbon monoxide produced reached 467.

[0112] In summary, the novel iron-based supramolecular catalyst prepared in the present invention has good catalytic activity for the photocatalytic carbon dioxide reduction reaction.

[0113] The above embodiments are preferred implementation methods of the present invention, but the implementation methods of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing an iron-based supramolecular catalyst, characterized in that: The steps are: Step a: 9-bromo-10-formylanthracene and 2,4-dimethylpyrrole are reacted in dichloromethane in the dark. After the reaction, the mixture is placed in an ice bath, trifluoroacetic acid is added, and then 2,3-dichloro-5,6-dicyanobenzoquinone is added to the solution. After the reaction, triethylamine and boron trifluoride etherate are added in an ice-water bath. After purification, compound 1 is obtained. The chemical reaction formula is: Step b: 4-hydroxyphenylboronic acid pinacol ester, 1,2-dibromoethane and anhydrous potassium carbonate were added to acetonitrile and reacted at 70° C. for 24 hours. After purification, compound 2 was obtained. The chemical reaction formula is: Step c: Dissolve compound 2 in N,N-dimethylformamide, add sodium azide, react at 100°C for 1 hour, and purify to obtain compound 3. The chemical reaction formula is: Step d: Compound 1, compound 3 and anhydrous potassium carbonate are reacted at 96°C for 6 hours under the catalysis of Pd(PPh3)4 to obtain compound 4 after purification. The solvent during the reaction is composed of toluene, ethanol and water in a volume ratio of 2:1:

2. The chemical reaction formula is: Step e: Dissolve 2-phenoxyethyl bromide in N,N-dimethylformamide, add sodium azide, stir at 100°C for 1 hour, and purify to obtain compound 5. The chemical reaction formula is: Step f: Dissolve anhydrous potassium carbonate and 4-hydroxybenzaldehyde in N,N-dimethylformamide, add propyne bromide dropwise, react for 12 hours, and purify to obtain compound 6. The chemical reaction formula is: Step g: Compound 6 and piperidine were added to anhydrous methanol, 1,2-butanedione was added dropwise, and the mixture was refluxed for 8 hours. After purification, compound 7 was obtained. The chemical reaction formula is: Step h: 1-(2-oxo-2-(pyridin-2-yl)ethyl)pyridin-1-ium iodide, compound 7 from step g, and anhydrous ammonium acetate were dissolved in anhydrous ethanol, reacted for 24 hours, and purified to obtain compound 8. The chemical reaction formula is: Step i: Compound 4 and Compound 8 are dissolved in a mixed solution of chloroform, ethanol and water, and reacted for 24 hours under the catalysis of sodium ascorbate and copper sulfate pentahydrate. After purification, Compound 9 and Compound 10 are obtained. The chemical reaction formula is: Step j: Compound 9 and ferrous perchlorate hydrate were dissolved in water and reacted at 120° C. for 24 hours. After purification, the iron-based supramolecular catalyst Fe-2BDP was obtained. The chemical reaction formula is: Step k: Compound 5 and compound 10 are dissolved in a mixed solution of chloroform, ethanol and water, and reacted for 24 hours under the catalysis of sodium ascorbate and copper sulfate pentahydrate. After purification, compound 11 is obtained. The chemical reaction formula is: Step 1: Compound 11 and ferrous perchlorate hydrate were dissolved in water and reacted at 120° C. for 24 hours. After purification, the iron-based supramolecular catalyst Fe-BDP was obtained. The chemical reaction formula is:

2. The method for preparing the iron-based supramolecular catalyst according to claim 1, wherein: The purification methods in steps a, b, and d and the purification methods in steps c, e, and f are all: first washing with a saturated sodium chloride solution, then drying over anhydrous sodium sulfate, then concentrating by rotary evaporation under reduced pressure, and finally performing chromatography on a silica gel column.

3. The method for preparing the iron-based supramolecular catalyst according to claim 1, wherein: In step a, the reaction time of 9-bromo-10-formylanthracene and 2,4-dimethylpyrrole is 15 minutes, the reaction time after adding trifluoroacetic acid is 6 hours, the reaction time after adding 2,3-dichloro-5,6-dicyanobenzoquinone is 15 minutes, and the reaction time after adding triethylamine and boron trifluoride etherate is 6 hours.

4. The method for preparing the iron-based supramolecular catalyst according to claim 1, wherein: The purification method in step h is: filtration under reduced pressure, and washing with anhydrous ethanol and ether.

5. The method for preparing the iron-based supramolecular catalyst according to claim 1, wherein: The purification method in step i and step k is: extraction with chloroform, washing with saturated sodium chloride solution, adding a small amount of ammonia water to the aqueous layer, separating the organic phase, drying with anhydrous sodium sulfate, then rotary evaporation and concentration, and finally chromatographic separation using a silica gel column.

6. The method for preparing the iron-based supramolecular catalyst according to claim 1, wherein: The purification method in step j and step l is: recrystallize the crude product with acetonitrile and diethyl ether, filter under reduced pressure, wash with pure water, dichloromethane and diethyl ether, and finally dry in vacuum.

7. Use of the iron-based supramolecular catalyst according to claim 1 in catalyzing the reduction of carbon dioxide to produce carbon monoxide, characterized in that: The steps are: adding iron-based supramolecular catalyst Fe-BDP or Fe-2BDP to N,N-dimethylformamide, using carbon dioxide as raw material and 1,3-dimethylbenzimidazole as sacrificial agent, and reducing carbon dioxide to carbon monoxide under light.

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