Center for Catalysis, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand.
Dalton Trans. 2019 Mar 5;48(10):3223-3230. doi: 10.1039/c8dt04699a.
Ligated metal(iii) complexes, Al(iii), In(iii), Cr(iii), and Co(iii), containing tetraphenylporphyrin (TPP) and cyclohexylsalen (Cy-salen) ligands were investigated for the polymerization of rac-lactide (rac-LA). A combination of metal complexes, co-catalyst, and co-initiator was shown to be highly efficient for the ring-opening polymerization of rac-LA at room temperature. Influences of metal centers, ligands, and co-catalysts were investigated. Higher Lewis acidity of metal centers and ligands enhanced catalytic activity. Ionic co-catalysts showed increased polymerization rates. Polymerization of rac-LA catalyzed by tetraphenylporphyrin aluminum chloride ((TPP)AlCl) and bis(triphenylphosphine)iminium chloride (PPN+Cl-) in cyclohexene oxide (CHO) as a solvent produced isotactic-enriched polylactide. The order of reactivities based on the metals supported by the TPP ligand is Cr(iii) > Al(iii) > In(iii) > Co(iii) while the reactivities of the catalysts supported by Cy-salen ligands are in the order In(iii) > Cr(iii) > Al(iii) > Co(iii).
含四苯基卟啉（TPP）和环己基席夫碱（Cy-salen）配体的金属（III）配合物，如 Al(III)、In(III)、Cr(III)和 Co(III)，被用于研究 rac-丙交酯（rac-LA）的聚合反应。研究表明，金属配合物、助催化剂和共引发剂的组合在室温下对 rac-LA 的开环聚合非常有效。研究了金属中心、配体和助催化剂的影响。金属中心和配体的路易斯酸度越高，催化活性越高。离子型助催化剂提高了聚合速率。TPP 氯化铝（(TPP)AlCl）和双（三苯基膦）亚胺盐酸盐（PPN+Cl-）在环己烯氧化物（CHO）溶剂中催化 rac-LA 聚合，生成等规富集的聚乳酸。基于 TPP 配体支持的金属的反应活性顺序为 Cr(III) > Al(III) > In(III) > Co(III)，而 Cy-salen 配体支持的催化剂的反应活性顺序为 In(III) > Cr(III) > Al(III) > Co(III)。
