A synthesis method and application of porphyrin metal organic framework nanomaterial catalyst

Abstract

The present invention discloses a method for synthesizing a class of porphyrin-based metal-organic framework catalysts and their applications. A triazine porphyrin moiety, prepared by reacting 2,2'-dipyrrolylmethane or its derivatives with 4-cyanobenzaldehyde, is used as a monomer. The monomer is reacted with a metal salt or an organometallic reagent via solvent thermal reaction and then purified to obtain a porphyrin-based metal-organic framework nanomaterial catalyst. The catalyst is then used, with or without a co-catalyst such as bis(triphenylphosphine)ammonium chloride, to catalyze the copolymerization of carbon dioxide, alkylene oxide, and cyclic anhydride to prepare a degradable poly(ester-carbonate). The catalyst is recovered by dissolving, precipitating, filtering, and then washing, and the catalyst is recycled multiple times for catalytic polymerization. The synthesis method of the present invention is relatively simple. By adjusting the substituents of the porphyrin moiety reaction precursor and the type of the coordination center metal ion, a catalyst system with rich structure is obtained. By adjusting the ratio and type of cyclic anhydride, alkylene oxide and CO2, aliphatic degradable poly(ester-carbonate) with different structures and molecular weights can be obtained. The porphyrin metal organic framework catalyst is easy to recycle and convenient to remove metal ion residues. The final polymer product structure is easy to degrade and has the advantages of low toxicity, biodegradability and excellent biocompatibility.

Description

Technical Field

[0001] The present invention relates to the field of catalytic polymerization, and in particular to the synthesis of a class of porphyrin-based metal organic framework catalysts, and their application in catalyzing the copolymerization of carbon dioxide (CO2), alkylene oxide and cyclic anhydride to prepare degradable poly(ester-carbonate). Background Art

[0002] A large number of petroleum-based plastics, such as polyethylene and polypropylene, are ubiquitous in society. These discarded plastics cannot be degraded, piling up like mountains, posing a threat to human health and creating a serious "white pollution" problem. Therefore, the development of biodegradable polymer materials has attracted considerable attention.

[0003] In recent years, the use of catalysts to catalyze the ternary copolymerization of CO2 / epoxyalkylene / cyclic anhydride to prepare biodegradable, heat-resistant, and mechanically excellent poly(ester-carbonate)s has been widely studied (Macromolecules, 2021, 54, 763-772; Macromolecules, 2011, 44(5), 1132-1139). Currently, there are many catalytic systems that can achieve the ternary copolymerization of CO2 / epoxyalkylene / cyclic anhydride. For example, the Coates group in the United States used β-diimine zinc catalyst to catalyze the ternary copolymerization of CO2, epoxycyclohexane, and cyclic anhydride (diglycolic anhydride or succinic anhydride) to synthesize polycarbonate-block-polyester diblock copolymers by a "one-pot" method (Angew. Chem. Int. Ed. 2008, 47(32), 6041-6044). The Duchateau research group used TPPCrCl and (Salen)CrCl as catalysts and 4-dimethylaminopyridine (DMAP) as a co-catalyst to catalyze the ternary copolymerization of CO2 / cyclohexene oxide / phthalic anhydride to prepare block copolymers (Prog.Org.Coat.2013,76(12),1704-1711). Professor Li Zhibo's research group successfully used Lewis acid-base pairs to catalyze the ternary copolymerization of CO2 / CHO / PA to prepare polycarbonate-block-polyester block copolymers by a one-pot or step-by-step method (Macromolecules,2021,54,763-772).

[0004] The catalysts in these systems are either metal coordination compounds or organic compounds, and all are small molecule catalytic systems. The associated synthesis and purification processes are often complex and demanding. Due to their small molecular weight, these catalysts often have good solubility, and the catalytic polymerization process is often a homogeneous system. After polymerization, the catalyst easily mixes with the polymer, making separation, recovery, or removal of the catalyst relatively difficult.

[0005] One of the typical catalytic systems is the porphyrin-metal coordination compound, which is a classic biomimetic compound, including a porphyrin metal center acting as a Lewis acid and a base on the porphyrin skeleton itself acting as a Lewis base. It has catalytic activity and plays an important role in catalyzing the ring-opening copolymerization of CO2 and alkylene oxide (Macromolecules 2012, 45, 6840-6849), the ring-opening copolymerization of alkylene oxide and cyclic anhydride (Polymer 2013, 54, 2639-2646; Polym.Chem., 2012, 3, 1308-1313) and the ring-opening polymerization of cyclic lactones (J.Porphyrins Phthalocyanines 2019, 23, 1020-1027). This type of catalyst can catalyze the copolymerization of various types of monomers with good catalytic effect. Based on it, the synthesis and preparation of various functional degradable polymers can be achieved. However, it also has the problem of being relatively difficult to separate, recycle or remove, which easily leads to catalyst residues, making it difficult to recycle and reuse the catalyst and reduce costs.

[0006] Achieving efficient separation of the catalyst from the polymer not only allows for catalyst recovery and reuse, thus reducing costs, but also avoids the presence of highly toxic and coloring metal-organic catalyst residues, thereby improving discoloration and degradation. Therefore, developing a catalytic system with high catalytic activity, ease of recycling, and simple preparation methods is a key challenge in preparing high-performance biodegradable poly(ester-carbonate).

[0007] Metal-organic frameworks (MOFs), porous coordination polymers composed of organic ligands and metal nodes, possess properties such as tunable pore size, large specific surface area, excellent thermal stability, and superior catalytic activity. They have been widely used in catalytic synthesis (Prog. Ener. Com. Sci., 2020, 80, 100849; Inorg. Chem. Front., 2021, 8, 590–619). In recent years, MOF nanomaterials have also begun to be used as catalysts in catalytic polymerization. For example, Professor Hou Linxi of Fuzhou University constructed a UiO-type MOF nanomaterial using terephthalic acid as the organic ligand backbone and Zr as the core. This material was successfully used to catalyze the copolymerization of epoxides and cyclic anhydrides (European Polymer Journal, 2024, 203, 112695). The catalyst in this system is recyclable and can be recycled for catalytic use. Experimental results show that after three cycles, its catalytic activity and the performance of the polymer products remain unchanged. Unfortunately, there are limited reports on the catalytic polymerization of metal-organic framework nanomaterials, and there are currently few reports on the types of monomers that can achieve catalytic polymerization. Summary of the Invention

[0008] In response to the above-mentioned problems existing in the prior art, in view of the high efficiency of porphyrin-metal coordination compounds and metal-organic framework nanomaterials in catalytic polymerization, the present invention provides a method for synthesizing a class of porphyrin-based metal-organic framework catalysts and their application in catalyzing the copolymerization of carbon dioxide, alkylene oxide and cyclic anhydride to prepare degradable poly(ester-carbonate), which can not only achieve efficient catalytic polymerization, but also achieve efficient separation, recovery and reuse of the catalyst.

[0009] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: a triazine porphyrin moiety prepared by the reaction of 2,2'-dipyrrolylmethane or its derivatives with 4-cyanobenzaldehyde is used as a monomer; the monomer is subjected to a solvent thermal reaction with a metal salt or an organic metal reagent (such as cobalt acetate) and purified to obtain a porphyrin-based metal organic framework nanomaterial catalyst; the catalyst is used in combination with or without a co-catalyst such as bis(triphenylphosphine) ammonium chloride to catalyze the copolymerization of carbon dioxide, alkylene oxide and cyclic anhydride to prepare a degradable poly(ester-carbonate); the catalyst is recovered by dissolving, precipitating, filtering and then washing, and the catalyst is recycled multiple times for catalytic polymerization.

[0010] A type of porphyrin-based metal-organic framework catalyst, composed of a nitrogen-containing porphyrin moiety acting as a Lewis base and a metal center acting as a Lewis acid, covalently bonded by a triazine group, exhibits a porous structure and can efficiently achieve catalytic polymerization. The structure of the porphyrin-based metal-organic framework catalyst is as follows:

[0011]

[0012] The catalyst structure is represented by a simplified chemical structure formula as follows:

[0013]

[0014] Where: M is the central metal ion, selected from Al 3+ , Mg 2+ , Zn 2+ ,Co 3+ , Fe 3+ , Cr 2+ , Mn 3+ , Cu 2+ , Ru 3+ , Pd 2+ ; R is selected from hydrogen, methyl, phenyl, 4-methylphenyl, 4-methoxyphenyl, 4-ethoxyphenyl, 4-chlorophenyl, 4-bromophenyl, 4-nitrophenyl, 4-carboxyphenyl, 3-carboxyphenyl, 3,5-dicarboxyphenyl, 4-carboxybiphenyl, pyridin-4-yl, pyridin-4-ethynyl, 4-(N,N-bipyridin-4-yl)phenyl, pyrazol-4-yl, 4-pyrazolphenyl, pentafluorophenyl or 4-(3-tri-tert-butylamino)phenyl.

[0015] The present invention also provides a method for synthesizing the porphyrin-based metal-organic framework catalyst, which comprises: dissolving 2,2'-dipyrrolylmethane or a derivative thereof and 4-cyanobenzaldehyde in a solvent, introducing an inert gas, adding trifluoroacetic acid, reacting and purifying at room temperature in the dark to obtain a triazine porphyrin moiety; then, using the triazine porphyrin moiety as a monomer, dissolving it together with trifluoromethanesulfonic acid in an organic solvent, freezing and thawing, evacuating, and filling with nitrogen, adding a metal salt or an organic metal reagent to the solution, heating for reaction, and purifying to obtain a porphyrin-based metal-organic framework nanomaterial catalyst.

[0016] Furthermore, in the above technical solution, the organic solvent is selected from dichloromethane or tetrahydrofuran; and the inert gas is selected from argon or nitrogen.

[0017] Furthermore, in the above technical solution, the metal salt or organometallic reagent is selected from diethylaluminum chloride, magnesium bromide, zinc acetate, cobalt acetate, ferric chloride, chromium chloride, manganese acetate, copper acetate, triruthenium dodecacarbonyl or dihydrogen tetrachloropalladium acid, and the heating reaction temperature is selected from 80-120°C.

[0018] The above synthesis method is expressed as follows using the chemical reaction formula:

[0019]

[0020] The present invention also describes the use of the porphyrin-based metal organic framework catalyst in catalyzing the copolymerization of carbon dioxide, alkylene oxide and cyclic anhydride to prepare degradable poly(ester-carbonate).

[0021] The reaction equation is expressed as:

[0022]

[0023] Furthermore, in the above technical solution, the catalytic system also includes a co-catalyst, which is selected from bis(triphenylphosphine)ammonium chloride (PPNCl), triphenylphosphine (PPh3), tetraphenylphosphine chloride (PPh4Cl), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and phosphazene base (t-BuP1 or t-BuP2).

[0024] Furthermore, in the above technical solution, the cyclic anhydride is maleic anhydride, succinic anhydride or itaconic anhydride, and the anhydride needs to be purified by multiple sublimations.

[0025] Furthermore, in the above technical solution, the alkylene oxide is ethylene oxide, propylene oxide, cyclohexene oxide or allyl glycidyl ether; and the carbon dioxide is of high purity, with a purity greater than 99.999%.

[0026] Furthermore, in the above technical solution, the polymerization reaction is bulk polymerization or solution polymerization; in bulk polymerization, alkylene oxide serves as a solvent; when the polymerization reaction adopts solution polymerization, the solvent is selected from tetrahydrofuran, dioxane, anisole, toluene, chloroform, acetonitrile or dimethyl sulfoxide.

[0027] Furthermore, in the above technical solution, the molar ratio of the alkylene oxide to the metal organic framework catalyst is 500-500000:1; the molar ratio of the metal organic framework catalyst to the co-catalyst is 0.2-5:1; the molar ratio of the cyclic anhydride to the alkylene oxide is 1:5-100; the carbon dioxide pressure is 0.1-5MPa; the copolymerization reaction temperature is 25-120°C, and the reaction is carried out under autogenous pressure for 5-48h.

[0028] Furthermore, in the above technical solution, after the catalyst reaction is completed, the mixed system after polymerization is recovered by dissolving with a solvent and filtered, the filter cake is fully washed with a dissolving solvent, and the solid in the filter cake is recovered after drying; after drying, the solid continues to act as a metal porphyrin organic framework catalyst and catalytic polymerization is repeated multiple times.

[0029] Furthermore, in the above technical solution, the solvent is selected from tetrahydrofuran, dioxane, chloroform or dichloromethane.

[0030] The present invention aims to provide a method for synthesizing a porphyrin-based metal-organic framework catalyst, and apply it to catalyze the copolymerization of carbon dioxide, alkylene oxide and cyclic anhydride to prepare degradable poly(ester-carbonate). Finally, the catalyst can be recovered by dissolving, precipitating, filtering and then washing the polymerization product, thereby realizing multiple recycling of the catalyst.

[0031] The present invention provides a method for synthesizing a porphyrin-based metal organic framework catalyst. By adjusting the substituents of the porphyrin-based reaction precursor, a series of porphyrin monomers with different structures can be obtained. By further adjusting the type of the coordination center metal ion, a porphyrin-based metal organic framework catalyst with rich structures can be obtained, with different structures and adjustable catalytic activity. The catalyst can be used to catalyze the copolymerization of carbon dioxide, alkylene oxide and cyclic anhydride to prepare degradable poly(ester-carbonate). By regulating the ratio of alkylene oxide and cyclic anhydride, alkylene oxide and catalyst and CO2 pressure, the molecular weight of the poly(ester-carbonate) can be effectively regulated, and the molecular weight can be adjusted from 1.0 to 12.0 kDa. The porphyrin-based metal organic framework catalyst can not only achieve efficient catalytic copolymerization of carbon dioxide, alkylene oxide and cyclic anhydride, but the system can also achieve efficient separation, recovery and reuse of the catalyst. After recovery, the catalyst can still effectively catalyze the copolymerization, which has many advantages. All of these make the related catalysts have broad application prospects, and the related poly(ester-carbonate) has important application value in the field of biopharmaceuticals and environmentally friendly polymer materials.

[0032] Advantageous Effects of the Invention

[0033] 1. The synthesis method of the porphyrin-based metal organic framework catalyst of the present invention is relatively simple. By adjusting the substituents of the porphyrin-based reaction precursor and the type of the coordination center metal ion, a structurally rich catalyst system with different structures and adjustable catalytic activity can be obtained;

[0034] 2. The use of porphyrin-based metal-organic framework catalysts can achieve the copolymerization of carbon dioxide, alkylene oxides and cyclic anhydrides to prepare degradable poly(ester-carbonate); while existing technologies mainly use metal coordination compounds or organic compounds as catalysts, all of which are small molecule catalytic systems. The related synthesis and purification processes are often complicated and tedious, and the synthesis conditions are harsh; and the related catalysts often have good solubility, and the catalytic polymerization process is mostly a homogeneous system. After the polymerization is completed, the catalyst is easily mixed with the polymer, and it is relatively difficult to separate, recover or remove the catalyst.

[0035] 3. Epoxides and cyclic anhydrides are abundant in variety and inexpensive. At the same time, epoxides and cyclic anhydrides are easy to chemically modify, which is conducive to the functionalization of materials. Using porphyrin-based metal-organic framework catalysts to catalyze the ring-opening copolymerization of epoxides with anhydrides and CO2 can obtain poly(ester-carbonates) with controllable structure and molecular weight.

[0036] 4. The ring-opening copolymerization of some alkylene oxides with acid anhydrides and CO2 catalyzed by porphyrin-based metal-organic framework catalysts can produce aliphatic poly(ester-carbonate) main chain structures. This type of structure can gradually degrade into small molecular compounds through physiological processes such as hydrolysis and enzymatic hydrolysis in the body. It has excellent biodegradability, low toxicity and good biocompatibility. Since the catalyst is easy to recycle and remove, the residual heavy metal ions in the polymer can be greatly reduced, which is beneficial to its application in fields such as biomaterials. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 For the triazine porphyrin monomer obtained in Example 1 1 H NMR;

[0038] Figure 2 The XRD pattern of the porphyrin-based metal organic framework catalyst obtained in Example 1;

[0039] Figure 3 1 is a SEM image of the porphyrin-based metal organic framework catalyst obtained in Example 1;

[0040] Figure 4 The poly (ester-carbonate) obtained in Example 21 1 H NMR;

[0041] Figure 5 This is the GPC spectrum of the poly(ester-carbonate) obtained in Example 21. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with specific implementations. The structures of the porphyrin-based metal organic framework catalysts obtained in the following examples of the present invention are determined by nuclear magnetic resonance spectroscopy ( 1 H NMR), X-ray diffraction (XRD) and scanning electron microscopy were used for characterization. The molecular weight and structure of poly(ester-carbonate) were determined by GPC and 1 H NMR determination. The relative molecular weight and molecular weight distribution of the polymers were determined using gel permeation chromatography (Viscotek 270 high performance liquid chromatography pump, Viscotek gel permeation chromatography columns (G2000HHR, G3000HHR, and G4000HHR), and Viscotek differential refractive index detector, containing chromatography-grade tetrahydrofuran (THF) at a column temperature of 35°C and a flow rate of 1.0 mL / min. NMR was performed on a Bruker Avance DMX 400 ( 1 The measurements were performed on a 400 MHz (H: 400 MHz) instrument using deuterated chloroform (CDCl3) as the solvent and tetramethylsilane (TMS) as the internal standard. The crystal structure of the porphyrin-based metal-organic framework catalyst was characterized using a PANalytical Empyrean X-ray diffractometer in the Netherlands, and the morphology of the porphyrin-based metal-organic framework catalyst was examined using a Hitachi S4800 scanning electron microscope in Japan.

[0043] The technical solutions of the present invention are described below through specific examples, which only provide some catalyst and catalytic polymerization examples.

[0044] Structure and number of some prepared catalysts:

[0045]

[0046]

[0047]

[0048]

[0049] Example 1: Preparation of Cat.1

[0050] 2 mmol of 2,2'-dipyrrolylmethane and 2 mmol of 4-cyanobenzaldehyde were dissolved in 400 mL of dichloromethane. Nitrogen was introduced for half an hour to remove the solvent and the air in the reaction flask. Nitrogen was continued to be introduced to allow the reaction to proceed in a nitrogen atmosphere. 0.27 mmol of trifluoroacetic acid was then added via a syringe. The reaction was allowed to proceed for 24 hours at room temperature in the dark. 3 mmol of dichlorodicyanobenzoquinone was then added. The reaction was continued for 4 hours. 3.6 mmol of triethylamine was then added, and the triazine porphyrin moiety was purified by column chromatography. 200 mg of the triazine porphyrin moiety monomer was weighed, 5 mL of trifluoromethanesulfonic acid was measured, and the mixture was dissolved in 5 mL of dichloromethane. The solvent was frozen in advance. The solution was freeze-thawed and vacuum-filled with nitrogen 3 to 5 times to fully remove dissolved oxygen, and then diethylaluminum chloride was added to the solution. The system was heated to melt and placed in an oil bath for reaction at a temperature of 120° C. After reacting for 48 hours, excess ammonia water was added to the reaction system to neutralize the system to obtain a solid precipitate, which was repeatedly washed with chloroform, acetone and ethanol in sequence for multiple times and then dried in vacuum to obtain Cat.1.

[0051] Example 2: Preparation of Cat.2

[0052] 2 mmol of 2,2'-(phenylmethylene)bis(1H-pyrrole) and 2 mmol of 4-cyanobenzaldehyde were dissolved in 400 mL of dichloromethane. Nitrogen was introduced for half an hour to remove the solvent and the air in the reaction flask. Nitrogen was continued to be introduced to allow the reaction to proceed in a nitrogen atmosphere. 0.27 mmol of trifluoroacetic acid was then added via a syringe. The reaction was allowed to proceed at room temperature in the dark for 24 hours. 3 mmol of dichlorodicyanobenzoquinone was then added, and the reaction was continued for 4 hours. 3.6 mmol of triethylamine was then added, and the triazine porphyrin moiety was purified by column chromatography. 200 mg of the triazine porphyrin moiety monomer was weighed, 5 mL of trifluoromethanesulfonic acid was measured, and the mixture was dissolved in 5 mL of dichloromethane. The solvent was frozen in advance. The solution was freeze-thawed and vacuum-filled with nitrogen 3 to 5 times to fully remove dissolved oxygen, and then diethylaluminum chloride was added to the solution. The system was heated to melt and placed in an oil bath for reaction at a temperature of 120° C. After reacting for 48 hours, excess ammonia water was added to the reaction system to neutralize the system to obtain a solid precipitate, which was repeatedly washed with chloroform, acetone and ethanol in sequence for multiple times and then dried in vacuum to obtain Cat.2.

[0053] Example 3: Preparation of Cat.3

[0054] 2 mmol of 2,2'-((4-nitrophenyl)methylene)bis(1H-pyrrole) and 2 mmol of 4-cyanobenzaldehyde were dissolved in 400 mL of dichloromethane. Nitrogen was introduced for half an hour to remove the solvent and the air in the reaction flask. Nitrogen was continued to be introduced to allow the reaction to proceed in a nitrogen atmosphere. 0.27 mmol of trifluoroacetic acid was then added via a syringe. The reaction was allowed to proceed at room temperature in the dark for 24 hours. 3 mmol of dichlorodicyanobenzoquinone was then added, and the reaction was continued for 4 hours. 3.6 mmol of triethylamine was then added, and the triazine porphyrin moiety was purified by column chromatography. 200 mg of the triazine porphyrin moiety monomer was weighed, 5 mL of trifluoromethanesulfonic acid was measured, and the mixture was dissolved in 5 mL of dichloromethane. The solvent was frozen in advance. The solution was freeze-thawed and vacuum-filled with nitrogen 3 to 5 times to fully remove dissolved oxygen, and then diethylaluminum chloride was added to the solution. The system was heated to melt and placed in an oil bath for reaction at a temperature of 120° C. After reacting for 48 hours, excess ammonia water was added to the reaction system to neutralize the system to obtain a solid precipitate, which was repeatedly washed with chloroform, acetone and ethanol in sequence for multiple times and then dried in vacuum to obtain Cat.3.

[0055] Example 4: Preparation of Cat.4

[0056] 2 mmol of 4-(bis(1H-pyrrol-2-yl)methyl)benzoic acid and 2 mmol of 4-cyanobenzaldehyde were dissolved in 400 mL of dichloromethane, and nitrogen was introduced for half an hour to remove the solvent and air in the reaction flask. The nitrogen was continued to be introduced to allow the reaction to proceed in a nitrogen atmosphere. 0.27 mmol of trifluoroacetic acid was then added via a syringe, and the reaction was allowed to proceed for 24 hours at room temperature in the dark. 3 mmol of dichlorodicyanobenzoquinone was then added, and the reaction was continued for 4 hours. 3.6 mmol of triethylamine was then added, and the mixture was purified by column chromatography to prepare a triazine porphyrin moiety. 200 mg of the triazine porphyrin moiety monomer was weighed, 5 mL of trifluoromethylsulfonic acid was measured, and the mixture was dissolved in 5 mL of dichloromethane. The solvent was frozen in advance. The solution was freeze-thawed and vacuum-filled with nitrogen 3 to 5 times to fully remove dissolved oxygen, and then diethylaluminum chloride was added to the solution. The system was heated to melt and placed in an oil bath for reaction at a temperature of 120° C. After reacting for 48 hours, excess ammonia water was added to the reaction system to neutralize the system to obtain a solid precipitate, which was repeatedly washed with chloroform, acetone and ethanol in sequence for multiple times and then dried in vacuum to obtain Cat.4.

[0057] Example 5: Preparation of Cat.5

[0058] 2 mmol of 4-(bis(1H-pyrrol-2-yl)methyl)pyridine and 2 mmol of 4-cyanobenzaldehyde were dissolved in 400 mL of dichloromethane, and nitrogen was introduced for half an hour to remove the solvent and the air in the reaction flask. The nitrogen was continued to be introduced to allow the reaction to proceed in a nitrogen atmosphere. 0.27 mmol of trifluoroacetic acid was then added via a syringe, and the reaction was allowed to proceed for 24 hours at room temperature in the dark. 3 mmol of dichlorodicyanobenzoquinone was then added, and the reaction was continued for 4 hours. 3.6 mmol of triethylamine was then added, and the mixture was purified by column chromatography to prepare a triazine porphyrin moiety. 200 mg of the triazine porphyrin moiety monomer was weighed, 5 mL of trifluoromethylsulfonic acid was measured, and the mixture was dissolved in 5 mL of dichloromethane. The solvent was frozen in advance. The solution was freeze-thawed and vacuum-filled with nitrogen 3 to 5 times to fully remove dissolved oxygen, and then diethylaluminum chloride was added to the solution. The system was heated to melt and placed in an oil bath for reaction at a temperature of 120° C. After reacting for 48 hours, excess ammonia water was added to the reaction system to neutralize the system to obtain a solid precipitate, which was repeatedly washed with chloroform, acetone and ethanol in sequence for multiple times and then dried in vacuum to obtain Cat.5.

[0059] Example 6: Preparation of Cat.6

[0060] 2 mmol of 2,2'-((perfluorophenyl)methylene)bis(1H-pyrrole) and 2 mmol of 4-cyanobenzaldehyde were dissolved in 400 mL of dichloromethane. Nitrogen was introduced for half an hour to remove the solvent and the air in the reaction flask. Nitrogen was continued to be introduced to allow the reaction to proceed in a nitrogen atmosphere. 0.27 mmol of trifluoroacetic acid was then added via a syringe. The reaction was allowed to proceed for 24 hours at room temperature in the dark. 3 mmol of dichlorodicyanobenzoquinone was then added. The reaction was continued for 4 hours. 3.6 mmol of triethylamine was then added, and the mixture was purified by column chromatography to prepare a triazine porphyrin moiety. 200 mg of the triazine porphyrin moiety monomer was weighed, 5 mL of trifluoromethanesulfonic acid was measured, and the mixture was dissolved in 5 mL of dichloromethane. The solvent was frozen in advance. The solution was freeze-thawed and vacuum-filled with nitrogen 3 to 5 times to fully remove dissolved oxygen, and then diethylaluminum chloride was added to the solution. The system was heated to melt and placed in an oil bath for reaction at 120°C. After the reaction time of 48 hours, excess ammonia water was added to the reaction system to neutralize the system to obtain a solid precipitate. The solid precipitate was repeatedly washed with chloroform, acetone and ethanol in sequence for multiple times and then dried in vacuum to obtain Cat.6.

[0061] Example 7: Preparation of Cat.7

[0062] 2 mmol of N,N-dibutyl-N-(3-(4-(di(1H-pyrrol-2-yl)methyl)phenyl)propyl)butan-1-ammonium and 2 mmol of 4-cyanobenzaldehyde were dissolved in 400 mL of dichloromethane. Nitrogen was introduced for half an hour to remove the solvent and air in the reaction flask. Nitrogen was continued to be introduced to allow the reaction to proceed in a nitrogen atmosphere. 0.27 mmol of trifluoroacetic acid was then added via a syringe. The reaction was carried out at room temperature in the dark for 24 hours. 3 mmol of dichlorodicyanobenzoquinone was then added, and the reaction was continued for 4 hours. 3.6 mmol of triethylamine was then added, and the mixture was purified by column chromatography to prepare a triazine porphyrin moiety. 200 mg of the triazine porphyrin moiety monomer was weighed, 5 mL of trifluoromethanesulfonic acid was measured, and the mixture was dissolved in 5 mL of dichloromethane. The solvent was frozen in advance. The solution was freeze-thawed and vacuum-filled with nitrogen 3 to 5 times to fully remove dissolved oxygen, and then diethylaluminum chloride was added to the solution. The system was heated to melt and placed in an oil bath for reaction at 120°C. After the reaction time of 48 hours, excess ammonia water was added to the reaction system to neutralize the system to obtain a solid precipitate. The solid precipitate was repeatedly washed with chloroform, acetone and ethanol in sequence for multiple times and then dried in vacuum to obtain Cat.7.

[0063] Examples 8-15: Preparation of Cat.8-Cat.15

[0064] Similar to the synthesis of Cat.1-7, the metal salt or organometallic reagent was replaced by diethylaluminum chloride and magnesium bromide.

[0065] Examples 16-21: Preparation of Cat.16-Cat21

[0066] Similar to the synthesis of Cat.1-7, the metal salt or organometallic reagent was replaced by cobalt acetate instead of diethylaluminum chloride.

[0067] Condition optimization experiment

[0068] Application Example 1-33: Preparation of Degradable Poly(ester-carbonate) by Copolymerization of Carbon Dioxide, Alkane Oxide, and Cyclic Anhydride Using Porphyrin-Based Metal-Organic Framework Catalysts with or Without Bis(triphenylphosphine)ammonium Chloride and Other Cocatalysts

[0069]

[0070] Application Example 1: In a nitrogen-filled glove box or a completely dry double-row tube system, a predetermined amount of Cat. 1, cyclohexene oxide, maleic anhydride (sublimed three times), and toluene were added to a dry autoclave. After the addition of the ingredients, the mixture was shaken to completely dissolve the monomers and catalyst. 3MPa of CO2 was then introduced and the mixture was placed in an 80°C oil bath under magnetic stirring for 12 hours. After the reaction, a small amount of the crude product was collected for NMR analysis to calculate the monomer conversion. The crude product was then precipitated three times in a mixed solvent of diethyl ether and n-hexane to obtain a purified product, which was then dried in a vacuum oven to yield poly(ester-carbonate). The cyclohexene oxide monomer conversion was 0, indicating no polymerization. The results are shown in Table 1.

[0071] Application Example 2: In a nitrogen-filled glove box or a completely dry double-row tube system, a predetermined amount of Cat. 1, bis(triphenylphosphine)ammonium chloride, cyclohexene oxide, maleic anhydride (sublimed three times), and toluene were added to a dry autoclave. After the addition of the ingredients, the mixture was shaken to completely dissolve the monomers and catalyst. 3MPa of CO2 was then introduced and the mixture was placed in an 80°C oil bath under magnetic stirring for 12 hours. After the reaction, a small amount of the crude product was collected for nuclear magnetic resonance analysis to calculate the monomer conversion. The crude product was then precipitated three times in a mixed solvent of diethyl ether and n-hexane to obtain a purified product, which was then dried in a vacuum drying oven to yield a poly(ester-carbonate). The cyclohexene oxide monomer conversion was 38%, the resulting polyester had a molecular weight of 1.1 kDa, and a molecular weight distribution of 1.80. The results are shown in Table 1.

[0072] Application Example 3-24: The polymerization and post-processing are similar to those in Application Example 1-2, except that the main catalyst, the porphyrin metal framework catalyst, is changed. The relevant polymerization results are shown in Table 1.

[0073] Application Examples 25-30: The polymerization and post-processing were similar to those in Application Examples 1-24, except that the main catalyst, the porphyrin metal framework catalyst, and the co-catalyst were changed. The relevant polymerization results are shown in Table 1.

[0074] Application Examples 31-33: The polymerization, post-treatment, and catalysts were identical to those in Application Examples 7, 15, and 23, except that the ratio of the primary catalyst, the porphyrin metal framework catalyst, to the monomer was changed. The polymerization results are shown in Table 1.

[0075] Table 1. Catalytic copolymerization results using different catalytic systems

[0076]

[0077]

[0078]

[0079] a Reaction 1-33 was carried out in toluene;b [Maleic anhydride]:[Cyclohexene oxide]:[Porphyrin metal organic framework catalyst]:[Lewis base co-catalyst] molar ratio; c Porphyrin metal organic framework catalyst; d Lewis base (cocatalyst), bis(triphenylphosphine)ammonium chloride (PPNCl), tetraphenylphosphine chloride (PPh4Cl), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU); e CO2 pressure is 3MPa; f The conversion of cyclohexene oxide monomer was determined by H NMR spectroscopy; g M n,SEC : number average molecular weight, determined by gel permeation chromatography; D M : Molecular weight distribution, determined by gel permeation chromatography.

[0080] Application Example 34: Catalyst Recovery and Reuse

[0081] After the polymerization is completed, the reaction mixture is redissolved with a large amount of tetrahydrofuran and filtered, the filtrate is discarded, and the insoluble matter is retained. During the filtration process, the filter cake (insoluble matter) is repeatedly washed with tetrahydrofuran and then placed in a vacuum drying oven to be fully dried.

[0082] In a nitrogen-filled glove box or a completely dry double-row tube system, a certain amount of recovered porphyrin metal framework catalyst, bis(triphenylphosphine)ammonium chloride, cyclohexene oxide, maleic anhydride (sublimed three times), and toluene were added to a dry autoclave. After the addition of the ingredients, the mixture was shaken evenly to completely dissolve the monomer and catalyst under stirring. 3MPa of CO2 was then introduced and the mixture was placed in an 80°C oil bath under magnetic stirring for 12 hours. After the reaction, a small amount of the crude product was collected for nuclear magnetic resonance analysis and calculation of the monomer conversion. The crude product was then precipitated three times in a mixed solvent of diethyl ether and n-hexane to obtain a purified product, which was then dried in a vacuum drying oven to obtain poly(ester-carbonate). Relevant polymerization data are shown in Table 2.

[0083] Application Examples 35-39: Catalyst recovery and reuse. The catalyst recovery and repolymerization process in the system is consistent with that in Application Example 34. The only difference is the different porphyrin metal organic framework catalysts used.

[0084] Application Example 40: The porphyrin metal organic framework catalyst Cat.21 was recovered for the second time and reused to participate in catalytic polymerization. The catalyst recovery and catalytic polymerization methods were consistent with those in Application Example 34.

[0085] Application Example 41: The porphyrin metal organic framework catalyst Cat.21 was recovered for the third time and reused to participate in catalytic polymerization. The catalyst recovery and catalytic polymerization methods were consistent with those in Application Example 34.

[0086] Table 2. Results of catalytic copolymerization of recycled porphyrin metal organic framework catalyst

[0087]

[0088]

[0089] a Reactions 34-41 were carried out in toluene; b The molar ratio of [maleic anhydride]:[cyclohexene oxide]:[recovered porphyrin metal organic framework catalyst]:[new Lewis base cocatalyst]; c Recycled porphyrin metal-organic framework catalysts; d Lewis base (cocatalyst), bis(triphenylphosphine)ammonium chloride (PPNCl); e CO2 pressure is 3MPa; f The conversion of cyclohexene oxide monomer was determined by H NMR spectroscopy; g M n,SEC : number average molecular weight, determined by gel permeation chromatography; D M : molecular weight distribution, determined by gel permeation chromatography; h 34-39 are the catalytic polymerization effects of the catalyst after one recovery, 40 is the catalytic polymerization effect after the second recovery, and 41 is the catalytic polymerization effect after the third recovery.

[0090] The above embodiments illustrate the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the scope of the principles of the present invention, and all such changes and improvements fall within the scope of protection of the present invention.

Claims

1. A porphyrin-based metal organic framework catalyst, characterized in that The structure is formed by covalent bonding of a nitrogen-containing porphyrin moiety acting as a Lewis base and a metal center acting as a Lewis acid through a triazine group. The structure presents a porous structure, and its general structural formula is as follows: Wherein: M is selected from Al, Mg or Co.

2. The method for synthesizing a porphyrin-based metal organic framework catalyst according to claim 1, wherein: The method comprises the following steps: using N,N-dibutyl-N-(3-(4-(di(1H-pyrrol-2-yl)methyl)phenyl)propyl)butan-1-ammonium to react with 4-cyanobenzaldehyde to obtain a triazine porphyrin moiety; using the triazine porphyrin moiety as a monomer, reacting with diethylaluminum chloride, magnesium bromide or cobalt acetate through solvent thermal reaction and purifying the reaction to obtain a porphyrin-based metal organic framework nanomaterial catalyst.

3. The method for synthesizing a porphyrin-based metal organic framework catalyst according to claim 2, wherein: The specific synthesis steps are as follows: dissolving N,N-dibutyl-N-(3-(4-(di(1H-pyrrol-2-yl)methyl)phenyl)propyl)butan-1-ammonium and 4-cyanobenzaldehyde in a solvent, introducing an inert gas, adding trifluoroacetic acid, reacting and purifying at room temperature in the dark to obtain a triazine porphyrin moiety; then using the triazine porphyrin moiety as a monomer, dissolving it together with trifluoromethanesulfonic acid in an organic solvent, freezing-thawing, vacuumizing and filling with nitrogen, adding diethylaluminum chloride, magnesium bromide or cobalt acetate to the solution, heating for reaction and purification to obtain a porphyrin-based metal-organic framework nanomaterial catalyst.

4. The method for synthesizing a porphyrin-based metal organic framework catalyst according to claim 2, wherein: The organic solvent is selected from dichloromethane or tetrahydrofuran; and the inert gas is selected from argon or nitrogen.

5. The method for synthesizing a porphyrin-based metal organic framework catalyst according to claim 2, wherein: The heating reaction temperature is selected from 80-120 o C.

6. Use of the porphyrin-based metal organic framework catalyst according to claim 1 in catalyzing the copolymerization of carbon dioxide, alkylene oxide and cyclic anhydride to prepare degradable poly(ester-carbonate).

7. Use of the porphyrin-based metal organic framework catalyst according to claim 6 in catalyzing the copolymerization of carbon dioxide, alkylene oxide and cyclic anhydride to prepare degradable poly(ester-carbonate), characterized in that: The reaction equation is expressed as: The catalytic system also includes a co-catalyst, which is bis(triphenylphosphine)ammonium chloride; the cyclic acid anhydride is maleic anhydride, succinic anhydride or itaconic anhydride, and the acid anhydride needs to be purified by multiple sublimations; the alkylene oxide is ethylene oxide, propylene oxide, cyclohexane or allyl glycidyl ether; the carbon dioxide is of high purity, with a purity greater than 99.999%; the copolymerization reaction is bulk polymerization or solution polymerization; in bulk polymerization, the alkylene oxide serves as a solvent; when the copolymerization reaction is solution polymerization, the solvent is selected from tetrahydrofuran, dioxane, anisole, toluene, chloroform, acetonitrile or dimethyl sulfoxide.

8. Use of the porphyrin-based metal organic framework catalyst according to claim 7 in catalyzing the copolymerization of carbon dioxide, alkylene oxide and cyclic anhydride to prepare a degradable poly(ester-carbonate), characterized in that: The molar ratio of the alkylene oxide to the metal organic framework catalyst is 500-500000:1; the molar ratio of the metal organic framework catalyst to the co-catalyst is 0.2-5:1; the molar ratio of the cyclic anhydride to the alkylene oxide is 1:5-100; the carbon dioxide pressure is 0.1-5 MPa; the copolymerization temperature is 25-120 o C, react under autogenous pressure for 5-48 h.

9. Use of the porphyrin-based metal organic framework catalyst according to claim 7 in catalyzing the copolymerization of carbon dioxide, alkylene oxide and cyclic anhydride to prepare a degradable poly(ester-carbonate), characterized in that: After the catalyst reaction is completed, the mixed system after polymerization is recovered by dissolving with a solvent and filtered. The filter cake is fully washed with the dissolving solvent and the solid in the filter cake is recovered after drying. The dried solid continues to act as a metalloporphyrin organic framework catalyst and catalytic polymerization is repeated multiple times.

10. Use of the porphyrin-based metal organic framework catalyst according to claim 9 in catalyzing the copolymerization of carbon dioxide, alkylene oxide and cyclic anhydride to prepare a degradable poly(ester-carbonate), characterized in that: The solvent is selected from tetrahydrofuran, dioxane, chloroform or dichloromethane.

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