Synthesis, Characterization And Photocatalytic Oxidation Property Of Visible-light-photoactive MOFs

With the development and progress of science and technology,mitigating and solving energy problems has become a hotspot for many scientists.Photocatalysis is considered as one of the most promising solutions.To date,a variety of materials have been used in photocatalytic reactions.Metal-organic frameworks?MOFs?are a class of microporous/mesoporous materials that have rapidly developed new inorganic-organic crystalline hybrids for nearly two decades.Due to the porosity,structural adjustability,the large specific surface and functionalization of metal-organic framework,which make it show great advantages in the field of photocatalysis.Designing and synthesizing novel MOFs photocatalysts and exploring related catalytic reaction have attracted more and more interests of researchers.In this paper,the photocatalytic properties of MOFs were realized by introducing functional ligand.Novel MOFs with different structural and physicochemical properties were coordinatedand synthesized via different types of metal ions and photoactive4,4?-?indol-9,10-bis?2,1-ethynylphenyl??dicarboxylic acid?ADBEB?as an organic ligand by solvothermal synthesis mehhod.The physical and chemical properties of MOFs were studied by powder X-ray diffraction,solid ultraviolet,electron paramagnetic resonance and other characterization methods.The properties and reaction mechanism of the synthesized MOFs in photocatalytic organic synthesis were further explored.1.In the first part of the work,we synthesized a novel double interpenetrating three-dimensional metal organic framework compound by solvothermal method using thiol dicarboxylic acid ligand and metal indium ion?1,[In?OH??ADBEB?]·DMF?.The results of physicochemical tests show that compound 1 has high chemical stability and thermal stability,exhibiting a broad band absorption in the visible range,thus it is an ideal photocatalytic material.We have studied the photocatalytic performance of the oxidative coupling reaction of benzylamine and the oxidation of thioanisole to sulfoxide with compound 1 as a photocatalyst.Photocatalytic experiments show that compound 1exhibits good photocatalytic activity and selectivity in the above oxidation reaction.We studied the catalytic reaction mechanism of this system by in-situ electron spin resonance technology.The results indicate that compound 1 activates the oxygen radical active species in the system by the charge transfer process during the reaction to achieve an oxidation reaction.2.In the second part of the work,we still used a anthracene dicarboxylic acid ligand ADBEB and Ln ions(Pr³⁺,Nd³⁺,Sm³⁺)to coordinate a series of Ln-MOFs 2 under solvothermal conditions.The molecular formula is([Ln?L?_1.5?H₂O?₃]·2DMA).The single crystal structure indicated that the series of compounds were three-dimensional structures.UV-vis spectrum indicated that the compound 2 had broad band visble light absorption based on photoactivity of the ligand.We used compound 2 as photocatalyst for the oxidative coupling reaction of amines.The experimental results show that compound 2?Nd?has efficiency photocatalytic properties,and the conversion of the benzylamine reaction can reach 99%in the 120 minutes under visible light irradiation at room temperature.The possible mechanism of the reaction was further verified by a series of quenching experiments.