Synthesis And Characterization Of Aluminum And Zinc Complexes And Their Catalysis In The Ring-Opening Polymerization Of Cyclic Esters

Aliphatic polyesters such as PCL, PLA, are widely used in the medical field, such as medical sutures, orthopedic materials, and drug delivery carrier, because of their biocompatible, biodegradable and permeability properties. These polyesters also are proposed as a sustainable alternative to petrochemical-based polyolefins in the fields of industry and agriculture. Recent years large number of reports show that numerous single-active-point metal catalyst systems can effectively initiate the ring-opening polymerization (ROP) of cyclic esters in a controlled fashion. And further few metallic catalytic systems exhibit good selectivity in ROP of rac-LA. In order to explore the fast and good selectivity of metal catalysts, and the interaction of the bi-metal centers in the binuclear metal catalyst for the ROP of cyclic esters, several single-and dual-core metal complexes have been designed and synthesized in my work. The main content is summarized as follows:The first chapter describes the significance of biodegradable aliphatic polyesters, the latest development of the metal catalysts for the ROP of cyclic esters, such as aluminum and zinc, the progress of metal catalysts with selectivity in ROP of rac-LA and the development of dual-core metal catalytic systems.The second chapter is on the synthesis and characterization a series of N,N,O-tridentate ligands and their supporting zinc complexes. In the presence of benzyl alcohol, all the zinc complexes rapidly catalyze the ROP of rac-LA efficiently in a controlled fashion. There also is on the synthesis and characterization of aluminum complexes supported by these ligands and their catalysis in the controlled ROP of ε-CL in the presence of benzyl alcohol.The third chapter presents the synthesis and characterization of zinc complexes supported by N,N,O-tridentate chiral ligands and their catalysis in the controlled ROP of rac-LA.The fourth chapter is on the synthesis, characterization of a series of dinuclear aluminum complexes supported by N,N,O-chelate ligands. In the presence of BnOH, the complexes are efficient catalysts for the ROP of s-CL in a controlled manner. Two aluminum centers in the dinuclear aluminum complexes have a cooperative effect in the ROP of ε-CL at [ε-CL]0=0.02M.The fifth chapter describes the synthesis, characterization of two classes of dinuclear aluminum complexes supported by N,O-chelate ligands. In the presence of BnOH, the complexes are efficient catalysts for the ROP of rac-LA. Two aluminum centers in the dinuclear aluminum complexes have a cooperative effect in the ROP of rac-LA.