New-generation pincer-type ruthenium complex, photosensitive function integrated crystalline framework catalytic material and preparation method and application thereof

Abstract

The invention discloses a new-generation pincer-type ruthenium complex, a photosensitive function integrated crystalline framework catalytic material and a preparation method and application thereof.The pincer-type ruthenium complex with the structure shown in the formula I and the longer fluorescence lifetime is introduced into an MOF framework, and the photosensitive function integrated crystalline framework catalytic material LCNC-Zr is assembled; the method has an obvious effect on photocatalytic reduction of CO2 into CO, and the optimal reaction rate for preparing CO can reach 1570 [mu] mol g <-1 > h <-1 >; the preparation method of the ligand and photosensitive function integrated crystalline framework catalytic material is mature, does not need harsh reaction conditions and complex processes, and can be used for large-scale preparation.

Description

Technical Field

[0001] This invention belongs to the field of metal-organic complex functional materials technology, specifically relating to a new generation of pincer-type ruthenium complex, a photosensitive functional integrated crystalline framework catalytic material, its preparation method and application. Background Technology

[0002] Since the Industrial Revolution, the continuously expanding population and increasingly intensive industrial production have jointly driven a rapid increase in greenhouse gas emissions. The World Meteorological Organization (WMO) released its 2025 Greenhouse Gas Bulletin, which stated that in 2024, the global average concentration of carbon dioxide (CO2) in the atmosphere reached a record high of 423.9 ± 0.2 ppm. Currently, the environmental hazards caused by greenhouse gases such as CO2 are becoming increasingly prominent, with problems such as global warming, accelerated glacial melting, and biodiversity loss emerging one after another. Therefore, there is an urgent need to develop effective strategies to control excessive CO2 emissions. Inspired by nature, artificial photosynthesis can not only convert carbon dioxide into valuable chemicals but also fully utilize solar energy, a renewable energy source. Therefore, researchers are dedicated to developing artificial photosynthesis systems.

[0003] Metal-organic frameworks (MOFs), with their extremely high specific surface area, tunable pore size distribution, and uniform and ordered structure, have demonstrated outstanding performance in gas adsorption and separation and heterogeneous catalysis. In recent years, various MOFs and their complexes have been developed and applied to photocatalytic carbon dioxide reduction (CO2RR) systems as highly efficient heterogeneous catalysts for artificial photosynthesis. Against this backdrop, numerous chemists and materials scientists have dedicated themselves to developing highly efficient photocatalytic CO2RR systems. The catalytic sites, namely the catalyst (Cat) and photosensitizer (PS), are two key components affecting photocatalytic performance. Scientists are committed to organically combining photosensitizers or co-catalysts with MOFs to develop heterogeneous catalysis based on molecular catalyst design. The matrix structure of MOFs not only facilitates the orderly assembly of photosensitive and catalytic centers but also allows control over parameters such as molecular orientation and spacing, enabling rapid electron and mass transport between multiple components and driving the highly efficient catalytic conversion of CO2.

[0004] According to reports, Mahmoud et al. prepared AUBM-4, a photosensitive functional compound, by introducing a photosensitizing 4-carboxyphenyl-terpyridine ruthenium complex into a MOF framework. Experimental results showed that the ruthenium complex and Zr formed a one-dimensional MOF with a chemically stable structure, which converted carbon dioxide into formate under visible light irradiation with a conversion rate of 366 μmol•g. -1 •h -1 Therefore, in photocatalytic systems, the strategy of using photosensitive complexes as linkers to construct MOF catalysts seems very promising. Summary of the Invention

[0005] For the reasons stated above, the first objective of this invention is to provide a new generation of clamp-type ruthenium complexes that introduce a nitrogen-heterocyclic carbene unit as a strong σ donor into the terpyridine ligand, thereby enabling triple metal-ligand charge transfer ( 3 MLCT (ruthenium chromatin) exhibits a longer excited-state lifetime and a fluorescence lifetime of up to 16.91 μs, making it a novel photosensitizer. In particular, the carboxyl groups at both ends of the ligand possess the ability to coordinate with transtransition metals, providing a possibility for ruthenium complexes to be assembled into metal-organic frameworks as ligands.

[0006] The second objective of this invention is to provide a new generation of pincer-type ruthenium complex preparation method, which uses ruthenium precursor compounds as raw materials and directly coordinates with nitrogen-containing heterocyclic carbene unit ligands to form pincer-type ruthenium complexes; without the need for harsh reaction conditions and complex processes.

[0007] The third objective of this invention is to provide a photosensitive integrated crystalline framework catalytic material, which uses a pincer-type ruthenium complex as a ligand and Zr atoms to assemble into a metal-organic framework. The photosensitizing properties of the pincer-type ruthenium complex itself are combined with the properties of the metal-organic framework to provide a heterogeneous photosensitizer and catalyst with good light-harvesting ability, thereby improving photocatalytic performance and making the catalyst recyclable.

[0008] The fourth objective of this invention is to provide a method for preparing a photosensitive functional integrated crystalline framework catalytic material, which can be prepared by a solvothermal reaction of a pincer-type ruthenium complex as a ligand and a Zr precursor; the reaction is mature and can be prepared on a large scale.

[0009] The fifth objective of this invention is to provide a photosensitive functional integrated crystalline framework catalytic material as a catalyst for the photocatalytic reduction of CO2, which can reduce CO2 to CO with high reaction rate and selectivity.

[0010] The first objective of this invention can be achieved by adopting the following technical solution:

[0011] A new generation of clamp-type ruthenium complexes, with the structural formula shown in Formula I:

[0012]

[0013] In Formula I, R1 and R2 are C1-C4 alkanes.

[0014] The second objective of this invention can be achieved by adopting the following technical solution:

[0015] A method for preparing a new generation of pincer-type ruthenium complex includes the following steps: the ligand with the structure shown in Formula II reacts with the ruthenium precursor in an ethylene glycol solution, and after the reaction is completed, the reaction solution is added to potassium hexafluorophosphate to obtain the new generation of pincer-type ruthenium complex with the structure shown in Formula I;

[0016]

[0017] In Formula II, R1 and R2 are C1-C4 alkanes.

[0018] Furthermore, the ruthenium precursor is one or more of ruthenium hydrochloride, acetate, nitrate, or their hydrates.

[0019] Furthermore, the molar ratio of the ligand to the ruthenium precursor in the structure shown in Formula II is (2-2.2):1.

[0020] Furthermore, the molar volume ratio of the ligand in the structure shown in Formula II to ethylene glycol is 1 mmol: (2-5) mL.

[0021] Furthermore, the reaction is carried out in an inert gas atmosphere; preferably, the inert gas is nitrogen.

[0022] Furthermore, the reaction temperature is 180-210℃, and the reaction time is 12-48h.

[0023] Further, after the reaction was completed, the mixture was cooled to room temperature, and the reaction solution was added dropwise to saturated potassium hexafluorophosphate to obtain the new generation of pincer-shaped ruthenium complex.

[0024] Furthermore, after the reaction solution is added to potassium hexafluorophosphate, solid-liquid separation is performed. The solid phase obtained is washed with water and ether and then dried to obtain the new generation of pincer-shaped ruthenium complex.

[0025] Furthermore, the process includes a purification step: dissolving the ruthenium complex in tetrahydrofuran, adding an aqueous LiOH solution, adjusting the pH to 1-3 to precipitate the precipitate; washing the precipitate with water and ether; and purifying it using silica gel column chromatography to obtain a new generation of clamp-type ruthenium complexes.

[0026] The third objective of this invention can be achieved by adopting the following technical solution:

[0027] A photosensitive functional integrated crystalline framework catalytic material comprises the aforementioned next-generation pincer ruthenium complex and Zr atoms. The carboxyl groups of the next-generation pincer ruthenium complex are coordinated and connected with Zr atoms to form an ordered stacked one-dimensional chain MOF, thereby obtaining the photosensitive functional integrated crystalline framework catalytic material.

[0028] The fourth objective of this invention can be achieved by adopting the following technical solution:

[0029] A method for preparing a photosensitive functional integrated crystalline framework catalytic material includes the following steps:

[0030] The aforementioned new-generation pincer-type ruthenium complex, as a ligand, was reacted with a Zr precursor via a solvothermal reaction to prepare a photosensitive functional integrated crystalline framework catalytic material.

[0031] Furthermore, the solvent for the solvothermal reaction is DMF.

[0032] Furthermore, the molar volume ratio of the new generation of clamp-type ruthenium complex to solvent is 1 μmol: (0.2-0.3) mL.

[0033] Furthermore, the molar ratio of the new generation of clamp-type ruthenium complex to Zr precursor is 1:(5-10).

[0034] Furthermore, the temperature of the solvothermal reaction is 100-140℃, and the reaction time is 24-120h.

[0035] Furthermore, the reaction is carried out in the presence of formic acid, with the amount of formic acid added being 20-30% of the solvent volume.

[0036] Furthermore, the reaction includes a post-processing step: solid-liquid separation is performed after the reaction, and the solid phase is washed with DMF, acetonitrile and acetone; after Soxhlet extraction and activation with acetone as solvent for 24-72 h, it is dried to obtain the photosensitive functional integrated crystalline framework catalytic material.

[0037] The fifth objective of this invention can be achieved by adopting the following technical solutions:

[0038] The above-mentioned photosensitive functional integrated crystalline framework catalytic material is used as a catalyst in photocatalytic CO2 reduction.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] 1. The new generation of pincer-type ruthenium complex of the present invention is not only a novel photosensitizer with a longer excited-state lifetime; in particular, the carboxyl groups at both ends of the pincer-type ruthenium complex of this application are reactive and can coordinate with transtransition metals to provide reaction sites, thereby integrating the photosensitizer into metal-organic framework materials to achieve a combination of photosensitivity and MOF performance.

[0041] 2. The preparation method of the new generation of pincer-type ruthenium complex of the present invention uses ruthenium precursor compound as raw material and directly coordinates with nitrogen-containing heterocyclic carbene unit ligand to form a pincer-type ruthenium complex; no harsh reaction conditions and complex process are required.

[0042] 3. The photosensitive functional integrated crystalline framework catalytic material of the present invention integrates the photosensitizer into the metal-organic framework material, realizing the combination of photosensitivity and MOF performance, providing a heterogeneous photosensitizer and catalyst with good light-harvesting ability, improving photocatalytic performance and making the catalyst recyclable.

[0043] 4. The preparation method of the photosensitive functional integrated crystalline framework catalytic material of the present invention can be prepared by solvothermal reaction of the pincer-type ruthenium complex as ligand and Zr precursor; the reaction is mature and can be prepared on a large scale.

[0044] 5. The application of the photosensitive functional integrated crystalline framework catalytic material of the present invention as a catalyst in photocatalytic CO2 reduction achieves a CO generation rate of 1570.4 μmol g. -1 h -1 The CO / H2 yield ratio is 224.3; it can reduce CO2 to CO with high reaction rate and selectivity. Attached Figure Description

[0045] Figure 1 The 1H NMR spectrum of [Ru(LCNC)2](PF6)2 prepared in Example 1;

[0046] Figure 2 Optical micrograph of LCNC-Zr prepared in Example 4;

[0047] Figure 3 Optical micrograph of [Ru(LCNC)2](PF6)2 prepared in Example 1;

[0048] Figure 4 This is a schematic diagram of the structure of [Ru(LCNC)2](PF6)2, where A is the crystal structure of [Ru(LCNC)2](PF6)2; B and C are three-dimensional axial views of the crystal of [Ru(LCNC)2](PF6)2.

[0049] Figure 5 This is a schematic diagram of the crystal structure of LCNC-Zr, where A represents the Zr-Ru-Zr chain of LCNC-Zr (color scheme: Ru, gold; Zr, green; C, gray; O, red; N, blue); B shows the distribution of channels between LCNC-Zr chains along the c-axis; C shows the stacking pattern between chains from the extension direction of the chains; and D shows the dislocation growth pattern between chains distinguished by different colors.

[0050] Figure 6 X-ray powder diffraction pattern of LCNC-Zr;

[0051] Figure 7 Thermogravimetric analysis diagram of LCNC-Zr;

[0052] Figure 8Infrared spectra of [Ru(LCNC)2](PF6)2 and LCNC-Zr;

[0053] Figure 9 X-ray powder diffraction patterns of LCNC-Zr after immersion in aqueous solutions of different solvents and pH values;

[0054] Figure 10 The image shows the XPS spectra of LCNC-Zr; where A is the full spectrum; B is the N 1s region; C is the Ru 3p region; and D is the Zr 3d region.

[0055] Figure 11 The results of the UV-Vis diffuse reflectance spectroscopy quantification of [Ru(LCNC)2](PF6)2 and LCNC-Zr are shown, where A is the UV-Vis absorption spectrum of [Ru(LCNC)2](PF6)2 and LCNC-Zr; and B is the Tauc plot of LCNC-Zr.

[0056] Figure 12 The photoluminescence results of [Ru(LCNC)2](PF6)2 and LCNC-Zr are shown; where A is the photoluminescence spectrum of [Ru(LCNC)2](PF6)2 and LCNC-Zr; B is the time-resolved emission trajectory of [Ru(LCNC)2](PF6)2; and C is the time-resolved emission trajectory of LCNC-Zr.

[0057] Figure 13 The results show the screening of photocatalytic CO2 reduction reaction conditions; where A represents the screening of sacrificial agents; B represents the screening of solvent systems; C represents the screening of solvent ratios; D represents the screening of MOF dosage; and E represents the screening of BIH sacrificial agent dosage.

[0058] Figure 14 The reaction rate diagram for 5 cycles of LCNC-Zr catalysis is shown.

[0059] Figure 15 X-ray powder diffraction pattern of LCNC-Zr catalysis;

[0060] Figure 16 The image shows the infrared spectrum of the LCNC-Zr catalyzed product. Detailed Implementation

[0061] The technical solution of the present invention will now be clearly and completely described with reference to specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0062] Currently available is ruthenium bipyridine [Ru(bpy)3] 2+And ruthenium tripyridine [Ru(tpy)2] 2+ It is a common photosensitizer in photocatalytic systems, but [Ru(bpy)3] 2+ It suffers from drawbacks such as optical and geometric heterogeneity, [Ru(tpy)2] 2+ Overcame [Ru(bpy)3] 2+ However, its short fluorescence lifetime limits its applications; nitrogen-heterocyclic carbene (NHC)ruthenium [Ru(CNC)2] has the disadvantage of short fluorescence lifetime. 2+ Introducing a strong ligand field of carbene effectively solves the fluorescence lifetime problem, and this is known as [Ru(tpy)2]. 2+ It is the best alternative, but it cannot be integrated into the MOF structure and therefore cannot play an efficient heterogeneous catalytic role.

[0063] Therefore, this application provides a new generation of clamp-type ruthenium complex, a photosensitive functional integrated crystalline framework catalytic material, its preparation method and application.

[0064] A new generation of clamp-type ruthenium complexes, with the structural formula shown in Formula I:

[0065]

[0066] In Formula I, R1 and R2 are C1-C4 alkanes.

[0067] Compared to nitrogen-containing heterocyclic carbene (NHC)ruthenium [Ru(CNC)2] 2+ The pincer-shaped ruthenium complex with the structure shown in Formula I of this application is itself a novel photosensitizer with a long fluorescence lifetime; secondly, benzoic acid structures are added to both ends of the ruthenium complex, with phenyl groups as linking groups, and carboxyl groups modified on [Ru(CNC)2]. 2+ Above; thus, the carboxylic acids at both ends can be assembled with transition metals to form a photosensitive integrated crystalline framework catalyst.

[0068] This application also provides a method for preparing the above-mentioned new generation of pincer-type ruthenium complex, including the following steps: the ligand with the structure shown in Formula II reacts with the ruthenium precursor in an ethylene glycol solution, and after the reaction is completed, the reaction solution is added to potassium hexafluorophosphate to obtain the new generation of pincer-type ruthenium complex with the structure shown in Formula I;

[0069]

[0070] In Formula II, R1 and R2 are C1-C4 alkanes.

[0071] In one embodiment, the reaction is carried out in an inert gas atmosphere; preferably, the inert gas is nitrogen. More preferably, the solvent ethylene glycol is subjected to deoxygenation treatment.

[0072] In one embodiment, the reaction temperature is 180-210°C, and the reaction time is 12-48 hours. Preferably, the reaction is carried out under reflux.

[0073] In one embodiment, after the reaction is complete, the mixture is cooled to room temperature, and the reaction solution is added dropwise to saturated potassium hexafluorophosphate to obtain the new generation of pincer-shaped ruthenium complex. When the cooled reaction solution is added dropwise to a saturated potassium hexafluorophosphate solution, the pincer-shaped ruthenium complex precipitates as hexafluorophosphate.

[0074] Therefore, solid-liquid separation is further performed. The separated solid phase is washed with water and ether, and then dried to obtain the new generation of pincer-shaped ruthenium complex. Solid-liquid separation is preferably performed by filtration. The separated solid phase is washed with water and ether, and then washed multiple times. The washed solid phase is dried to obtain the crude product of the new generation of pincer-shaped ruthenium complex. Preferably, vacuum drying is used.

[0075] One embodiment also includes a purification step. In this embodiment, the purification method can be varied. Optionally, the crude product is dissolved in tetrahydrofuran, and an aqueous LiOH solution is added to adjust the pH to 1-3 to precipitate. The precipitate is washed with water and ether, and then purified by silica gel column chromatography to obtain a new generation of pincer-type ruthenium complex. The LiOH content in the aqueous LiOH solution is 1.5-3 times the equivalent of the crude product. The pH is adjusted using concentrated hydrochloric acid, which is added dropwise to adjust the pH.

[0076] Optionally, further purification can be achieved by silica gel column chromatography using a mixture of acetonitrile / methanol / saturated KPF6 solution at a volume ratio of (45-50):(45-50):2 as the eluent. The eluent is collected, and the solvent is removed to obtain the new generation of pincer-shaped ruthenium complex. This can be used in subsequent experimental steps.

[0077] As one embodiment, the ruthenium precursor is one or more of ruthenium hydrochloride, acetate, nitrate or their hydrate.

[0078] As one implementation, the molar ratio of the ligand to the ruthenium precursor shown in Formula II is (2-2.2):1.

[0079] As one embodiment, the molar volume ratio of the ligand in Formula II to ethylene glycol is 1 mmol: (2-5) mL.

[0080] This application provides a photosensitive functional integrated crystalline framework catalytic material, comprising the aforementioned new generation of pincer-type ruthenium complex and Zr atoms. The carboxyl groups of the new generation of pincer-type ruthenium complex are coordinated and connected with Zr atoms to form an ordered stacked one-dimensional chain MOF, thereby obtaining the photosensitive functional integrated crystalline framework catalytic material.

[0081] A single Zr atom acts as a metal node, coordinating with the carboxyl groups at the ends of two different pincer-shaped ruthenium complexes. As the terminal carboxylic acids extend, an ordered, stacked one-dimensional chain-like metal-organic framework material is ultimately formed. This successfully integrates photosensitizers into the metal-organic framework material, achieving a synergistic integration of photosensitivity and a crystalline framework.

[0082] As one implementation method, the photosensitive functional integrated crystalline framework catalytic material is monoclinic with space group P21 / n , a=13.3633Å, b=22.4580Å, c=17.1250Å, α=γ= 90 o β=109.575 o The unit cell volume is 4842.4 Å. 3 .

[0083] This application also provides a method for preparing a photosensitive functional integrated crystalline framework catalytic material, comprising the following steps:

[0084] The aforementioned new-generation pincer-type ruthenium complex, as a ligand, was reacted with a Zr precursor via a solvothermal reaction to prepare a photosensitive functional integrated crystalline framework catalytic material.

[0085] In this application, a pincer-shaped ruthenium complex is used as a ligand to assemble with Zr atoms via a solvothermal reaction to form a metal-organic framework material. Solvothermal reaction is a conventional method for preparing MOFs, and the pincer-shaped ruthenium complex used as a ligand in this application can also be assembled with Zr atoms via a solvothermal reaction.

[0086] In one implementation method, the solvent for the solvothermal reaction is DMF. The molar volume ratio of the new generation of clamp-type ruthenium complex to the solvent is 1 μmol: (0.2-0.3) mL.

[0087] As one implementation method, the molar ratio of the new generation of clamp-type ruthenium complex to Zr precursor is 1:(5-10).

[0088] In one embodiment, the temperature of the solvothermal reaction is 100-140°C, and the reaction time is 24-120 h.

[0089] As one implementation method, the reaction is carried out in the presence of formic acid, with the amount of formic acid added being 20-30% of the solvent volume.

[0090] As one embodiment, the reaction also includes a post-processing step: solid-liquid separation is performed after the reaction, and the solid phase is washed with DMF, acetonitrile and acetone; after Soxhlet extraction and activation with acetone as solvent for 24-72 h, it is dried to obtain the photosensitive functional integrated crystalline framework catalytic material.

[0091] This application also provides the application of the above-mentioned photosensitive functional integrated crystalline framework catalytic material as a catalyst in photocatalytic CO2 reduction.

[0092] The following is a further explanation using specific embodiments.

[0093] Example 1: Synthesis of a new generation of clamp-type ruthenium complexes with the structure shown in Formula I

[0094] 6.94 mmol of the compound with the structure shown in Formula I (R1=R2 being methyl) and 3.47 mmol of ruthenium chloride trihydrate were added to a 100 mL Erlenmeyer flask with a ground glass stopper. 25 mL of deoxygenated ethylene glycol solution was added, and the mixture was stirred at 200 °C for 24 h under a N2 atmosphere. After the reaction was completed, the mixture was cooled to room temperature, and the reaction solution was added dropwise to 500 mL of a stirred saturated KPF6 solution. Precipitation occurred, and the residue was filtered. The residue was washed with water (3 × 10 mL) and diethyl ether (3 × 10 mL), respectively, and dried under vacuum to obtain the crude product.

[0095] The crude product was dissolved in tetrahydrofuran, and 250 mL of 2 eq LiOH aqueous solution was added. After stirring at room temperature for 12 h, concentrated hydrochloric acid was slowly added dropwise to the LiOH aqueous solution under ice bath conditions to adjust the pH to 2. A precipitate appeared, and the product was filtered. The filter residue was washed with water (3 × 10 mL) and ether (3 × 10 mL) respectively, and then dried under vacuum to obtain the solid.

[0096] Further purification was performed by silica gel column chromatography. Elution was carried out using a mixture of acetonitrile / methanol / saturated KPF6 solution at a volume ratio of 49:49:2. The eluent was collected, and the solvent was removed by rotary evaporation to obtain 1.93 g of a new generation of pincer-shaped ruthenium complex, with a yield of 50.0%. It was named [Ru(LCNC)2](PF6)2. The 1H NMR spectrum is shown below. Figure 1 As shown.

[0097] 1 H NMR (400MHz, CD3OD)δ=8.57(s,2H),8.52(s,2H), 8.33-8.27(s,4H), 7.26(s,2H), 2.80(s,6H).

[0098] Example 2: Synthesis of a new generation of clamp-type ruthenium complexes with the structure shown in Formula I

[0099] 7.29 mmol of the compound with the structure shown in Formula I (R1=R2 being methyl) and 3.47 mmol of ruthenium chloride trihydrate were added to a 100 mL Erlenmeyer flask with a ground glass stopper. 15 mL of deoxygenated ethylene glycol solution was added, and the mixture was stirred at 180 °C for 48 h under a N2 atmosphere. After the reaction was completed, the mixture was cooled to room temperature, and the reaction solution was added dropwise to 500 mL of a saturated KPF6 solution under stirring. The precipitate was formed, filtered, and the residue was washed with water (3 × 10 mL) and diethyl ether (3 × 10 mL), respectively. The residue was then dried under vacuum to obtain the crude product.

[0100] The crude product was dissolved in tetrahydrofuran, and 250 mL of 2 eq LiOH aqueous solution was added. After stirring at room temperature for 12 h, concentrated hydrochloric acid was slowly added dropwise to the LiOH aqueous solution under ice bath conditions to adjust the pH to 3. A precipitate appeared, and the product was filtered. The filter residue was washed with water (3 × 10 mL) and ether (3 × 10 mL) respectively, and then dried under vacuum to obtain the solid.

[0101] Further purification was achieved by silica gel column chromatography. Elution was performed using a mixture of acetonitrile / methanol / saturated KPF6 solution at a volume ratio of 49:49:2. The eluent was collected, and the solvent was removed by rotary evaporation to obtain a new generation of pincer-shaped ruthenium complexes.

[0102] Example 3: Synthesis of a new generation of clamp-type ruthenium complexes with the structure shown in Formula I

[0103] 7.63 mmol of the compound with the structure shown in Formula I (R1=R2 are methyl) and 3.47 mmol of ruthenium chloride trihydrate were added to a 100 mL Erlenmeyer flask with a ground glass stopper. 38 mL of deoxygenated ethylene glycol solution was added, and the mixture was stirred at 210 °C for 12 h under a N2 atmosphere. After the reaction was completed, the mixture was cooled to room temperature, and the reaction solution was added dropwise to 500 mL of saturated KPF6 solution under stirring. Precipitation occurred, and the residue was filtered. The residue was washed with water (3 × 10 mL) and diethyl ether (3 × 10 mL), respectively, and dried under vacuum to obtain the crude product.

[0104] The crude product was dissolved in tetrahydrofuran, and 250 mL of 2 eq LiOH aqueous solution was added. After stirring at room temperature for 12 h, concentrated hydrochloric acid was slowly added dropwise to the LiOH aqueous solution under ice bath conditions to adjust the pH to 1. A precipitate appeared, and the product was filtered. The filter residue was washed with water (3 × 10 mL) and ether (3 × 10 mL) respectively, and then dried under vacuum to obtain the solid.

[0105] Further purification was achieved by silica gel column chromatography. Elution was performed using a mixture of acetonitrile / methanol / saturated KPF6 solution at a volume ratio of 49:49:2. The eluent was collected, and the solvent was removed by rotary evaporation to obtain a new generation of pincer-shaped ruthenium complexes.

[0106] Example 4: Preparation of a photosensitive functional integrated crystalline framework catalytic material

[0107] 9 μmol of the [Ru(LCNC)2](PF6)2 ligand prepared in Example 1 and 60 μmol of zirconium tetrachloride were weighed into a 10 mL vial. 2.5 mL of DMF and 700 μL of formic acid were added, and the mixture was dissolved by sonication. The solution was then heated in a 120 °C oven for 72 h. After cooling, blocky crystals were obtained. These crystals were washed with DMF, acetonitrile, and acetone, respectively, and then activated in a Soxhlet extractor with acetone solution for 48 h. After drying, 6.7 mg of a photosensitive integrated crystalline framework catalytic material crystal product was obtained and named LCNC-Zr. The crystal micrograph is shown below. Figure 2 As shown.

[0108] Example 5: Preparation of a photosensitive functional integrated crystalline framework catalytic material

[0109] 9 μmol of the [Ru(LCNC)2](PF6)2 ligand prepared in Example 1 and 45 μmol of zirconium tetrachloride were weighed into a 10 mL vial. 2.7 mL of DMF and 540 μL of formic acid were added, and the mixture was dissolved by sonication. The solution was then heated in an oven at 100 °C for 120 h. After cooling, block crystals were obtained. The crystals were washed with DMF, acetonitrile, and acetone, respectively, and then activated with acetone solution in a Soxhlet extractor for 48 h. After drying, 6.7 mg of the photosensitive functional integrated crystalline framework catalytic material crystal product was obtained and named LCNC-Zr.

[0110] Example 6: Preparation of a photosensitive functional integrated crystalline framework catalytic material

[0111] 9 μmol of the [Ru(LCNC)2](PF6)2 ligand prepared in Example 1 and 90 μmol of zirconium tetrachloride were weighed into a 10 mL vial. 1.8 mL of DMF and 540 μL of formic acid were added, and the mixture was dissolved by sonication. The solution was then heated in an oven at 140 °C for 24 h. After cooling, block crystals were obtained. The crystals were washed with DMF, acetonitrile, and acetone, respectively, and then activated with acetone solution in a Soxhlet extractor for 48 h. After drying, 6.7 mg of the photosensitive functional integrated crystalline framework catalytic material crystal product was obtained and named LCNC-Zr.

[0112] Characterization and performance testing

[0113] 1. Crystal structure and X-ray powder diffraction test of the product

[0114] 4.8 mg of [Ru(LCNC)2](PF6)2 prepared in Example 1 was weighed and dissolved in 600 μL of DMF. Crystallization was carried out at 120 °C to obtain bulk single crystals. Figure 3As shown in Table 1, single-crystal diffraction tests were performed using a Rigaku XtaLAB Synergy diffractometer. Data were collected at 300 K using Cu-Ka (=1.54178 Å). Reflectance was reduced using SAINTV8.38A, and absorption correction was performed on the files using SADABS-2016 / 2. Space groups were assigned, and the structure was solved directly using ShelXS1. All reflections were refined using ShelXL in the Olex-2 software package via full-matrix least squares for F2. The crystallographic parameters are shown in Table 1.

[0115] Table 1. Crystallographic parameters of ligand [Ru(LCNC)2](PF6)2

[0116]

[0117] The single-crystal data clearly show that [Ru(LCNC)2] 2+ The structure of the monomer is as follows Figure 4 As shown, and as can be seen from the three-dimensional axis, [Ru(LCNC)2] 2+ The monomers grew along the b-axis, and the growth direction of the monomers remained consistent. Combined with 1H NMR spectroscopy and single-crystal structure data, the successful preparation of the [Ru(LCNC)2](PF6)2 ligand was effectively demonstrated.

[0118] Single-crystal diffraction tests were performed on the LCNC-Zr prepared in Example 4 using a Rigaku XtaLAB Synergy diffractometer. Data were collected for the single crystal at 300 K using Cu-Ka (=1.54178 Å). Reflectance was reduced using SAINT V8.38A, and absorption correction was performed on the files using SADABS-2016 / 2. Space groups were assigned, and the structure was solved using a direct method with ShelXS1. All reflections were refined using ShelXL in the Olex-2 software package via full-matrix least squares for F2. Crystallographic parameters are shown in Table 2; X-ray powder diffraction patterns are shown below. Figure 6 As shown.

[0119] Table 2 Crystallographic parameters of LCNC-Zr

[0120]

[0121] Single-crystal data collection data show that LCNC-Zr is a monoclinic crystal system with space group P21 / n , a=13.3633Å, b=22.4580Å, c=17.1250Å, α=γ= 90 o β=109.575 o The unit cell volume is 4842.4 Å. 3 .

[0122] Its asymmetric unit contains a complete [Ru(LCNC)2] 2+ The single Zr atom acts as a metal node, possessing octetability. It coordinates with two different terminal carboxyl groups of the monomer. The remaining coordination sites can coordinate with oxygen atoms, DMF molecules, and formic acid molecules, thereby neutralizing the charge of the +4 valence metal Zr. The deprotonated carboxylate groups at both ends of the monomer cancel out the charge of the central divalent ruthenium, resulting in an overall neutral charge structure. As the terminal carboxylate groups extend, they eventually form an ordered stacked 1D chain-like MOF (such as...). Figure 5 As shown in the diagram. Looking along the c-axis, it can be seen that the stacking of chains creates channels, which facilitates the rapid transport of molecules, matter, and electrons.

[0123] The X-ray powder diffraction (XRD) results show that the XRD pattern of the fresh LCN-Zr sample is in good agreement with the XRD pattern based on single-crystal structure simulation. The positions of the diffraction peaks in the patterns correspond well. Although there are differences in the relative intensities of some peaks, this is mainly due to the crystal orientation effect commonly seen in actual tests. This difference is within a reasonable range, indicating that the prepared sample is a pure phase.

[0124] 2. Thermogravimetric analysis test

[0125] The LCNC-Zr prepared in Example 4 was subjected to thermogravimetric analysis (TGA) under a nitrogen atmosphere. The TGA results are shown in the figure below. Figure 7 As shown.

[0126] Thermogravimetric analysis (TGA) revealed a 4% weight loss in LCNC-Zr at 142℃, attributed to the release of free guest molecules within the pores. A further 3% weight loss occurred between 142℃ and 336℃, likely due to further separation of guest molecules and the shedding of DMF, formic acid, and other molecules coordinated to the Zr. A significant weight loss of nearly 29% occurred between 336℃ and 704℃, primarily due to the slow decomposition of ligands. After 704℃, the weight loss slowed, mainly due to the further decomposition of residual small amounts of organic matter or carbonaceous material. Finally, at 900℃, 60.4% of the sample remained, consisting of metal oxides such as zirconium oxide and ruthenium oxide. The metallic framework material exhibited good thermal stability.

[0127] 3. Infrared spectroscopy test

[0128] Infrared spectroscopy was performed on [Ru(LCNC)2](PF6)2 prepared in Example 1 and LCNC-Zr prepared in Example 4; the infrared spectra are shown below. Figure 8 As shown.

[0129] As clearly observed from the infrared spectrum, the ligand prepared in Example 1 contains 1682 cm⁻¹ -1The characteristic peak of carboxylic acid disappeared in the LCNC-Zr prepared in Example 4, indicating that the carboxylic acid functional group in the ligand coordinated with the metal Zr.

[0130] 4. Solvent and pH stability test

[0131] The LCNC-Zr prepared in Example 4 was soaked in different solvents and at different pH values ​​for 3 days, then dried and subjected to X-ray powder diffraction analysis. The results are as follows: Figure 9 As shown.

[0132] Experimental results show that the PXRD of LCNC-Zr can be maintained after immersion in DMF for 3 days, and under conditions of dichloromethane, exposure to air, acetone, acetonitrile, methanol, and ethanol, the PXRD value is 7.3. o The 2θ PXRD characteristic peak shifts to higher angles, which is attributed to the contraction of the aperture, but the overall diffraction is maintained.

[0133] After immersion in water and aqueous solutions of different pH values ​​for 3 days, LCNC-Zr PXRD underwent a phase transition at 8.7. o 11.1 o 14.1 o 17.1 o Four characteristic peaks were observed at 2θ, indicating that the MOF after the phase transition tended to be stable, maintaining the same stable phase at pH 3-11. The phase-transformed MOF could be obtained by treating LCNC-Zr with water for one day. Single-crystal data could be collected using a Rigaku XtaLAB Synergy diffractometer. The phase-transformed sample was basically consistent with the simulated XRD of the single crystal. However, due to crystal orientation issues during actual testing, there was a slight deviation in the peak intensity between the water-treated sample and the simulated XRD, which is considered an acceptable and normal experimental deviation.

[0134] 5. XPS characterization

[0135] The LCNC-Zr prepared in Example 4 was subjected to X-ray photoelectron spectroscopy (XPS) testing. The XPS plot is shown below. Figure 10 As shown in the figure. Where A is the full spectrum; B is the N 1s region; C is the Ru 3p region; and D is the Zr 3d region.

[0136] X-ray photoelectron spectroscopy analysis revealed that the Ru 3p group of metallic Ru... 1 / 2 and Ru 3p 3 / 2 Signals (484.53 eV and 462.30 eV), Zr 3d metal 3 / 2 and Zr 3d 5 / 2The signals (185.17 eV and 182.73 eV) indicate that Ru and Zr are in divalent and tetravalent states, respectively. Analysis reveals characteristic 2p region absorptions of imidazole N and pyridine N in the N 1s region. The results clarify the chemical environment of the metal center, determine the metal valence state, and identify the characteristic absorptions of N.

[0137] 6. Ultraviolet characterization

[0138] The [Ru(LCNC)2](PF6)2 prepared in Example 1 and the LCNC-Zr prepared in Example 4 were subjected to UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The UV absorption spectra and Tauc plots of LCNC-Zr are shown below. Figure 11 As shown.

[0139] LCNC-Zr retains the absorption characteristics of [Ru(LCNC)2](PF6)2 in the UV-Vis region, exhibiting a strong absorption peak in the ~600nm range. This absorption range is attributed to... Transition excitation composition. Based on absorption spectroscopy, it can be inferred that in LCNC-Zr, [Ru(LCNC)2]... 2+ The charge transfer to Zr (LCCT) absorption is not significant, therefore this absorption band is attributed to the singlet metal-ligand charge transfer of the Ru complex in the MOF structure. 1 MLCT). The Kubelka-Munk function is used to convert the UV absorption spectrum into a Tauc plot (e.g., ...). Figure 11 B), its optical bandgap can be calculated to be 2.07 eV.

[0140] 7. Photoluminescence

[0141] The photoluminescence spectra of [Ru(LCNC)2](PF6)2 prepared in Example 1 and LCNC-Zrd prepared in Example 4 are shown below. Figure 12 As shown, A is the photoluminescence spectrum; B is the time-resolved emission trajectory of [Ru(LCNC)2](PF6)2; and C is the time-resolved emission trajectory of LCNC-Zr.

[0142] [Ru(LCNC)2](PF6)2 and LCNC-Zr maintain similar emission peaks in the 500-800 nm range after being excited by 420 nm light. Figure 11 A) indicates that LCNC-Zr inherits the luminescence properties of [Ru(LCNC)2](PF6)2, further indicating that it is based on Ru IIThe complex exhibits MLCT state luminescence. Luminescence decay analysis shows that [Ru(LCNC)2](PF6)2 has a lifetime of 16.91 μs, while LCNC-Zr, although slightly reduced, still reaches the 10 μs level (11.46 μs). Its fluorescence lifetime is longer than that of any known bipyridine Ru-based MOF.

[0143] 8. Photocatalytic CO2 reduction performance

[0144] Without adding an external photosensitizer, using LCNC-Zr as a catalyst, in pure acetonitrile solvent, under visible light irradiation (λ)... ex Screening for CO2RR sacrificial agents was conducted at ≥420 nm. When 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzis[d]imidazole (BIH) was used as the sacrificial agent, the results were obtained by gas chromatography and... 1 ¹H NMR was used to detect the catalytic products. Photocatalysis only yielded gaseous products. The detection results showed that the main product was CO and the byproduct was H₂. Furthermore, LCNC-Zr showed good selectivity for CO.

[0145] Secondly, according to literature reports, solvents such as proton sources like H2O are often added during catalysis because many reduction mechanisms involve H2O. + The participation of [the relevant parties] was investigated. Following the literature method, a small amount of protic solvents (H2O, MeOH, EtOH, TEOA) were added to acetonitrile solvent. It was found that only H2O and MeOH could effectively reduce CO2, while the others only produced hydrogen. MeOH's performance was inferior to H2O. Therefore, the final reaction system was determined to be acetonitrile / H2O, with BIH as the sacrificial agent.

[0146] The amounts of H2O and sacrificial agent were also screened. The results of the screening of reaction conditions are as follows: Figure 13 As shown. The optimal CO2RR conditions were finally optimized as follows: acetonitrile / H2O = 9:1 v / v, sacrificial agent BIH (8 mg) and 3 mg LCNC-Zr, catalysis for 3 h.

[0147] The experimental and control catalytic experiments were set up under the above conditions, as shown in Table 3:

[0148] Table 3. Comparison of catalytic experiments

[0149]

[0150] Under the optimal CO2RR conditions, the best CO performance achieved using the LCNC-Zr from this application reached 1570 μmol g. −1 h −1The CO / H2 ratio reaches 224, indicating that the LCNC-Zr of this application exhibits excellent catalytic CO2 reduction reaction rate and significant selectivity for CO under the above reaction conditions.

[0151] 9. Cyclic performance of LCNC-Zr catalyst

[0152] After the LCNC-Zr catalyst reaction was completed, it was washed and dried, and the catalytic reaction was repeated 5 times, with the reaction rate as follows each time: Figure 14 As shown in the figure. In five cycles of the experiment, the catalytic performance of LCNC-Zr was well maintained. After each cycle, regeneration was achieved by replenishing the sacrificial agent and re-introducing CO2 in an ice bath. The X-ray powder diffraction pattern of the catalyst after five cycles is shown in the figure. Figure 15 As shown; Infrared spectrum as shown Figure 16 As shown.

[0153] The PXRD spectrum shows that the catalyzed material retains the powder diffraction characteristics of the original material. The infrared spectrum at 1682 cm⁻¹ after catalysis... -1 The absence of characteristic peaks for carboxylic acids indicates that the coordination of carboxylic acid functional groups is still maintained, and the stretching vibration regions in other areas show no significant changes, suggesting that the catalyzed MOF material remains stable.

[0154] In summary, this application utilizes cyclic carbene (NHC)ruthenium [Ru(CNC)2] 2+ By modifying the MOF and introducing benzoic acid groups, the pincer-shaped ruthenium complex can be used as a ligand to assemble with metal atoms into a metal-organic framework. The photosensitizer is then incorporated into the MOF to obtain a heterogeneous catalyst. This heterogeneous photosensitizer not only has good light-harvesting ability but is also a highly efficient catalyst. Furthermore, it enables the recycling of photocatalysts and achieves efficient photocatalytic CO2 to CO production.

[0155] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A new generation of clamp-type ruthenium complex, characterized in that, The structural formula is shown in Formula I: ， In Formula I, R1 and R2 are C1-C4 alkanes.

2. The method for preparing the new generation of clamp-type ruthenium complex according to claim 1, characterized in that, Includes the following steps: The ligand with the structure shown in Formula II reacts with the ruthenium precursor in an ethylene glycol solution. After the reaction is completed, the reaction solution is added to potassium hexafluorophosphate to obtain a new generation of pincer-type ruthenium complex with the structure shown in Formula I. ， In Formula II, R1 and R2 are C1-C4 alkanes.

3. The method for preparing the new generation of clamp-type ruthenium complex according to claim 2, characterized in that, The ruthenium precursor is one or more of the ruthenium hydrochloride, acetate, nitrate or their hydrate; The molar ratio of the ligand to the ruthenium precursor in the structure shown in Formula II is (2-2.2):1; The molar volume ratio of the ligand in the structure shown in Formula II to ethylene glycol is 1 mmol: (2-5) mL.

4. The method for preparing the new generation of clamp-type ruthenium complex according to claim 2, characterized in that, The reaction is carried out in an inert gas atmosphere; preferably, the inert gas is nitrogen. The reaction temperature is 180-210℃, and the reaction time is 12-48h.

5. The method for preparing the new generation of clamp-type ruthenium complex according to claim 2, characterized in that, After the reaction was completed, the mixture was cooled to room temperature, and the reaction solution was added dropwise to saturated potassium hexafluorophosphate to obtain the new generation of pincer-shaped ruthenium complex. After the reaction solution was added to potassium hexafluorophosphate, solid-liquid separation was performed. The solid phase obtained was washed with water and ether and then dried to obtain the new generation of pincer-shaped ruthenium complex. Preferably, the process further includes a purification step: dissolving in tetrahydrofuran, adding LiOH aqueous solution, adjusting the pH to 1-3 to precipitate; washing the precipitate with water and ether; The new generation of clamp-type ruthenium complexes were obtained by purification using silica gel column chromatography.

6. A photosensitive functional integrated crystalline framework catalytic material, characterized in that, The new generation of pincer-type ruthenium complex and Zr atoms as described in any one of claims 1-5 are used to form an ordered stacked one-dimensional chain MOF, thereby obtaining the photosensitive functional integrated crystalline framework catalytic material.

7. The preparation method of the photosensitive functional integrated crystalline framework catalytic material according to claim 6, characterized in that, Includes the following steps: The new generation of pincer-type ruthenium complex as described in any one of claims 1-5 is used as a ligand to react with a Zr precursor via a solvothermal reaction to prepare a photosensitive functional integrated crystalline framework catalytic material.

8. The method for preparing the photosensitive functional integrated crystalline framework catalytic material according to claim 7, characterized in that, The solvent for the solvothermal reaction is DMF; The molar-volume ratio of the new generation of clamp-type ruthenium complex to solvent is 1 μmol: (0.2-0.3) mL; The molar ratio of the new generation of clamp-type ruthenium complex to Zr precursor is 1:(5-10); The temperature of the solvothermal reaction is 100-140℃, and the reaction time is 24-120h; The reaction is carried out in the presence of formic acid, with the amount of formic acid added being 20-30% of the solvent volume.

9. The method for preparing the photosensitive functional integrated crystalline framework catalytic material according to claim 6, characterized in that, The reaction also includes a post-processing step: solid-liquid separation is performed after the reaction, and the solid phase is washed with DMF, acetonitrile and acetone; after Soxhlet extraction and activation for 24-72 h with acetone as solvent, it is dried to obtain the photosensitive functional integrated crystalline framework catalytic material.

10. The application of the photosensitive functional integrated crystalline framework catalytic material according to any one of claims 6-9 as a catalyst in photocatalytic CO2 reduction.

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