作者：Lei Li； Bo Liu；Dongtao Liu；Chunji Wu； Shihui Li； Bo Liu and Dongmei Cui
关键字：aluminum complexes， binuclear structures，elemental analyses， immortal
论文来源：期刊
具体来源：http://pubs.acs.org/doi/pdf/10.1021/om5008264
发表时间：2014年

A series of aluminum complexes L^aAl₂Me₄ (1), L^b₂Al₄Me₄ (2), and L^cAl₂Me₄ (3) have been prepared from the reaction of AlMe₃ with Salan- and Salen-type ligands (L^aH₂ = [2-OH-3,5-^tBu₂-C₆H₂CH₂N(CH₃)]₂-(m-phenylene); L^bH₄ = [2-OH-3,5-^tBu₂-C₆H₂CH₂NH]₂-(m-phenylene); L^cH₂ = [2-OH-3,5-^tBu₂-C₆H₂CH═N]₂-(m-phenylene)), respectively. All these complexes were characterized by NMR spectroscopy, X-ray diffraction, and elemental analyses, with complexes 1and 3 adopting binuclear structures, while complex 2 being tetranuclear. In the presence of alcohol, the binuclear complexes 1 and 3 catalyzed controlled ring-opening homopolymerizations of both ε-CL and l-LA. In the copolymerization experiments, complexes 1 and 2 produced tapered copolymers of ε-CL and l-LA, while complex 3 was able to provide ε-CL-co-l-LA with tendentially random structure indicated by the average lengths of the caproyl and lactidyl sequences (L_CL = 1.4; L_LA = 2.6). Particularly, addition of excess alcohol into the catalytic system of complex 3 established the first “immortal” copolymerization of ε-CL/l-LA, which accelerated the polymerization rates of both monomers and, thus, afforded random copolymers with predictable molecular weights and narrow molecular weight distributions.