Zinc Complexes Containing Pyrazolyl-phenolate Ligands: Synthesis, Characterization and Application in Ring-Opening Polymerization of L-Lactide

• Main Authors: Bo-Yu Huang, 黃勃喻
• Other Authors: Chi-Tien Chen
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/aew8y8

碩士 === 國立中興大學 === 化學系所 === 99 === A series of pyrazolyl-phenolate ligand precursors L1H-L6H, [L1H = HPzHPhOH; L2H = HPzMePhOH; L3H = HPztBuPhOH; L4H = MePzHPhOH; L5H = MePzMePhOH; L6H = MePztBuPhOH] were synthesized via copper- catalyzed N-arylation in good yields. The reactions of L1H-L4H and L6H with 1.2 equivalent of ZnEt2 yielded [(μ-HPzHPhO)ZnEt]2 (Zn1), [(μ-HPz MePhO)ZnEt]2 (Zn2), [(μ-HPztBuPhO)ZnEt]2 (Zn3), [(μ-MePzHPhO)ZnEt]2 (Zn4) and [(μ-MePztBuPhO)ZnEt]2 (Zn6), respectively. Complexes Zn1-Zn4 and Zn6 are dimeric bridging through the phenolato oxygen atoms of the ligands. The reactions of L1H-L6H with 0.5 equivalent of ZnEt2 yielded {(HPzHPhO)2Zn} (Zn7), {(HPzMePhO)2Zn} (Zn8), {(HPztBu PhO)2Zn} (Zn9), {(MePzHPhO)2Zn} (Zn10), {(MePzMePhO)2Zn} (Zn11) and {(MePztBuPhO)2Zn} (Zn12), respectively. All these compounds were characterized by NMR spectroscopy and elemental analysis. The molecular structures of complexes Zn4, Zn6, Zn11 and Zn12 were determined by sigle-crystal X-ray diffraction techniques. Complexes Zn1-Zn4 and Zn6 show catalytic activities for the ring-opening polymerization of L-lactide in the presence of BnOH, with good molecular weight control and yields polymer with a very narrow mo-lecular weight distribution. They also exhibit both “ living ” and “ immortal ” characters. Nevertheless, Complexes Zn7-Zn12 show catalytic inactivities for the ring-opening polymerization of L-lactide in the presence of BnOH. Polymer end group was analyzed by the 1H NMR spectrum and MALDI-ToF mass spectrum.