| Summary: | 博士 === 國立中興大學 === 化學系所 === 101 === A series of zinc benzylalkoxide complexes, magnesium benzylalkoxide complexes, and aluminum methyl complexes supported by NNO-tridentate pyrazolonate ligands with various electron withdrawing -donating subsituents have been synthesized and characterized. X-ray crystal structural studies and PGSE experimental revealed that complexes 1a, 2a, 5a, 1b, 2b, 4b and 5b are dinuclear bridging through the benzylalkoxy oxygen atoms with penta-coordinated metal centers. However, the aluminum complex 1c exhibits a monomeric feature with a tetra-coordinated Al center different from the penta-coordinated aluminum complex 4c. Based on kinetic studies, the activity of the magnesium complexes is significantly influenced by the electronic effect of the ancillary ligands with the electron-donating substituents at the phenyl rings enhancing the polymerization rate. All the zinc and magnesium complexes have acted as efficient initiators for the ring-opening polymerization of L-lactide. The ring-opening polymerization (ROP) of caprolactone, decalactone,butyrolactone and their copolymer with complexes 1a and 1b were investigated. It is interesting to note that aluminum complexes bearing O,N,N,O-tetradntate ligand are excellent efficient initiators for the ring-opening polymerization of caprolactone.
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