Study On Synthesis And Catalysis For CO₂ Conversion Of Hydrazone Rare Earth Complexes

CO₂ is considered as one of the main greenhouse gases that lead to global warming.On the other hand,it is also regarded as an abundant,non-toxic,renewable carbon source.The conversion of carbon dioxide into high value-added chemicals not only helps to alleviate the greenhouse effect,but also effectively realizes“turning waste into treasure”,causing widespread concern among researchers.Among them,the chemical fixation of CO₂ into cyclic carbonates is one of the most promising methods,due to its line with atomic economics and sustainable development requirements.However,the high thermal stability of CO₂ limits its application,and the development of catalyst systems with excellent performance is the focus of our research.In this paper,we designed and synthesized a series of novel hydrazide-based rare earth complexes,and systematically studied its catalytic performance in the preparation of cyclic carbonates by catalytic reaction of carbon dioxide with epoxy compounds,and further explored the structure-activity relationship of a series of hydrazide complexes.The specific work is as follows:?1?Introduce the structure of hydrazide compounds and the application of its rare earth metal complexes in medicine,light,magnetism and catalysis.And summarizes the research progress of metal complexes catalyzing the reaction of carbon dioxide with epoxide to synthesize cyclic carbonates in recent years.?2?Three novel heteropolynuclear complexes?Zn₄Ln₂L₄?have been synthesized by solvothermal method using a pyridylhydrazide ligand?HL¹?.And used to catalyze the reaction of carbon dioxide and epoxide to synthesize cyclic carbonates.It was found that these 3d-4f polynuclear complexes exhibited excellent catalytic properties,high selectivity and wide substrate scope under mild conditions.Subsequently,we studied its catalytic mechanism.?3?Two series of supramolecular rare earth complexes have been synthesized by using ligand?HL¹?and rare earth salts with cations.And regulated the ligand HL¹terminal group to synthesis the salicylaldehyde pyridine hydrazide ligand?HL²?.In the process of culturing the crystal,we synthesized a systematical structure evolution of the supramolecular rare earth complexes from quad-nuclear quadrilateral to nine-nuclear“sandwich”for the first time.Subsequently,we studied the catalytic performance of this series of supramolecular rare earth complexes for the cycloaddition reaction of carbon dioxide and epoxide,and studied its catalytic mechanism.