Self-Assembly And Application Of Chiral Multinuclear Rare-Earth Metal Complexes

Multinuclear complex,such as cage,ring,short chain or cluster,is a kind of specific supramolecular material with nanometer scale constructed by the self-assembly of two or more metal ions and organic ligands,which has enormous application potential in luminescence,electricity,magnetism,catalysis,molecular recognition,biological imaging and medicine.The research of multinuclear complexes based on transition metals has received increasing attention,but it still need further exploration and research for the self-assemby of multinuclear rare-earth metal complexes.In order to understand the relationship between the structure and properties of multinuclear rare-earth metal complexes,we designed and synthesized a series of chiral acylhydrazone organic ligands and obtained a series of chiral multinuclear rare-earth metal complexes by self-assembly.Further,the application of some multinuclear rare-earth metal complexes as catalyst has been studied in detail.This thesis is divided into four chapters.Chapter 1.The construction methods and research progress of multinuclear complexes were summarized.The coordination characteristics and the application of multinuclear rare-earth metal complexes were briefly illustrated.The usual chiral/achiral catalyst systems in the cycloaddition reaction of CO₂ with epoxide were described.Chapter 2.A class of chiral acylhydrazone ligands based on L-alanine have been designed and synthesized,and a series of dinuclear rare earth complexes have been obtained by self-assembly.Taking the advantage of more active sites in multinuclear rare-earth metal complex and chirality of ligand,the complexes were applied to the synthesis of chiral cyclic carbonates.In addition,the application of these complexes in near-infrared luminescence has also been explored and evaluated.Chapter 3.Two series of new acylhydrazone ligands（H₂L² and H₂L³）have been synthesized based on the previous work.Then two kinds of tetranuclear rare earth complexes,[Ln₄L₄²（H₂O）₂]·4Cl·7H₂O（Ln=Eu（III）,Er（III）,Dy（III））and[La₄{（R/S）-L³}₄（NO₃）]·3NO₃·6H₂O,have been obtained,which successfully transfer the chiral signal from the ligand to the complex.Chapter 4.A chiral acylhydrazone ligand,H₂L⁴,was synthesized based on chiral1,2-cyclohexanedicarboxylic acid.And then a new kind of tetranuclear Eu（III）helicate has been self-assembled by H₂L⁴ and four lanthanide ions.The cavity consist of four Eu（III）ions in the complex could effectively fix CO₂ in the atmosphere,and releases CO₂ under the condition of dilute sulphuric acid.In addition,the tetranuclear rare-earth metal helicate exhibited higher catalytic activity for the cycloaddition reaction of CO₂ to epoxide.