Synthesis of Sodium Complexes Supported with NNO-Tridentate Schiff Base Ligands and Their Applications in the Ring-Opening Polymerization of l-Lactide

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• 作者：Hsiu-Wei Ou ; Kai-Hsuan Lo ; Wei-Ting Du ; Wei-Yi Lu ; Wan-Jung Chuang ; Bor-Hunn Huang ; Hsuan-Ying Chen ; Chu-Chieh Lin
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：February 15, 2016
• 年：2016
• 卷：55
• 期：4
• 页码：1423-1432
• 全文大小：600K
• ISSN：1520-510X

文摘

A series of sodium complexes bearing NNO-tridentate Schiff base ligands with an N-pendant arm were synthesized and used as catalysts for the ring-opening polymerization of l-lactide (l-LA). Electronic effects of ancillary ligands coordinated by sodium complexes substantially influence the catalysis, and ligands with electron-donating groups increase the catalytic activity of the sodium complexes for catalyzing l-LA polymerization. In particular, a sodium complex bearing a 4-methoxy group has the highest activity with conversion up to 95% within 30 s at 0 °C and a low polydispersity index of 1.13, whereas the 4-bromo group showed the poorest performance with regard to the catalytic rate of l-LA polymerization in the presence of benzyl alcohol (BnOH). ¹H NMR pulsed-gradient spin–echo diffusion experiments and single-crystal X-ray analyses showed that sodium complexes [L^HNa(THF)]₂ and [L^4-ClNa(THF)]₂ were dinuclear species in both solution and the solid state. The kinetic results indicated a first-order dependence on each of [[L^4-ClNa]₂], [l-LA], and [BnOH].