title: Synthesis of Sodium Complexes Supported with NNO-Tridentate Schiff Base Ligands and Their Applications in the Ring-Opening Polymerization of L-Lactide.
abstract: 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). (1)H NMR pulsed-gradient spin-echo diffusion experiments and single-crystal X-ray analyses showed that sodium complexes [L(H)Na(THF)]2 and [L(4-Cl)Na(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-Cl)Na]2], [l-LA], and [BnOH].
authors.affiliation: Department of Chemistry, National Chung Hsing University , Taichung 402, Taiwan, Republic of China.
authors.forename: Hsiu-Wei
authors.initials: HW
authors.lastname: Ou
authors.affiliation: Department of Chemistry, National Chung Hsing University , Taichung 402, Taiwan, Republic of China.
authors.forename: Kai-Hsuan
authors.initials: KH
authors.lastname: Lo
authors.affiliation: Department of Chemistry, National Chung Hsing University , Taichung 402, Taiwan, Republic of China.
authors.forename: Wei-Ting
authors.initials: WT
authors.lastname: Du
authors.affiliation: Department of Chemistry, National Chung Hsing University , Taichung 402, Taiwan, Republic of China.
authors.forename: Wei-Yi
authors.initials: WY
authors.lastname: Lu
authors.affiliation: Department of Medicinal and Applied Chemistry, Kaohsiung Medical University , Kaohsiung 80708, Taiwan, Republic of China.
authors.forename: Wan-Jung
authors.initials: WJ
authors.lastname: Chuang
authors.affiliation: Department of Chemistry, National Chung Hsing University , Taichung 402, Taiwan, Republic of China.
authors.forename: Bor-Hunn
authors.initials: BH
authors.lastname: Huang
authors.affiliation: Department of Medicinal and Applied Chemistry, Kaohsiung Medical University , Kaohsiung 80708, Taiwan, Republic of China.
authors.forename: Hsuan-Ying
authors.initials: HY
authors.lastname: Chen
authors.affiliation: Department of Chemistry, National Chung Hsing University , Taichung 402, Taiwan, Republic of China.
authors.forename: Chu-Chieh
authors.initials: CC
authors.lastname: Lin