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A series of bis-ligated zinc complexes supported by Schiff base ligands were successfully synthesized and characterized by ~1H,~(13)C NMR,elemental analysis,and X-ray crystallography.These zinc complexes can be used as catalysts for the polymerization of rac-lactide in solution as well as in molten lactide.The results show that all catalysts exhibited high catalytic activity and obtained moderate heterotactic PLAs with the expected molecular weight.Complex 1 can catalyze the polymerization of rac-lactide under controllable conditions with living and immortal character in toluene solution.In addition,the steric hindrance and electronic effects has a great influence on the catalytic activity and selectivity of catalysts.
A series of bis-ligated zinc complexes supported by Schiff base ligands were successfully synthesized and characterized by ~ 1H, ~ (13) C NMR, elemental analysis, and X-ray crystallography. The zinc complexes can be used as catalysts for the polymerization of rac-lactide in solution as well as in molten lactide. The results show that all catalysts exhibited high catalytic activity and gave moderate heterotactic PLAs with the expected molecular weight. Complex 1 can catalyze the polymerization of rac-lactide under controllable conditions with living and immortal character in toluene solution. addition, the steric hindrance and electronic effects has a great influence on the catalytic activity and selectivity of catalysts.