| Summary: | 碩士 === 國立中興大學 === 化學系所 === 104 === Eleven novel bimetallic nickel complexes incorporated by benzotriazole-containing ligand (C83CBiIBTP or C85CBiIBTP), [(C83CBiIBTP)Ni2(O2CCF3)2] (1), [(C85CBiIBTP)Ni2(O2CCF3)2] (2), [(C83CBiIBTP)Ni2(O2CPh)2] (3), [(C85CBiIBTP)Ni2(O2CPh)2] (4), [(C83CBiIBTP)Ni2(O2CC6H4-4-CF3)2] (5), [(C85CBiIBTP)Ni2(O2CC6H4-4-CF3)2] (6), [(C83CBiIBTP)Ni2(O2CC6H4-4-OMe)2] (7), [(C83CBiIBTP)Ni2(O2CPh)(ClO4)(H2O)] (8), [(C85CBiIBTP)Ni2(O2CPh)(ClO4)(H2O)] (9), [(C83CBiIBTP)Ni2(O2CPh)(MeOH)2]ClO4 (10), [(C83CBiIBTP)Ni2(O2CPh)(EtOH)2]ClO4 (11) have been synthesized and structurally characterized. Complexes 1-11 were synthesized by Salen-type ligands precursor C83CBiIBTP-H2 and C85CBiIBTP-H2 with metal precursor Ni(OCl4)•6H2O, as well as different proportions of organic carboxylic acids. The catalytic efficiencies for copolymerization of carbon dioxide (CO2) and epoxides were systematic studied.
Complexes 1-9 was applied to copolymerize CO2 with cyclohexene oxide (CHO) to compare their activities. Complexes 1-7 are demonstrated to be active catalysts for CHO/CO2 copolymerization as well as the formation of highly alternating poly (cyclohexene carbonate) in a controllable manner. Among them, nickel complex 1 with trifluoroacetate co-ligand reveals the best activity (TOF>430 h-1) and gives the polycarbonate with high molecular weight. CF3 group-featuring di-nickel complexes 1、2、5 and 6 were found to efficiently copolymerize CO2 and CHO, giving a high molecular weight (Mn>16,000 g/mol). In addition, complex 3 is also an active catalyst for the copolymerization of CO2 with cyclohexene oxide on addition of benzoic acid as the chain transfer reagent to give the low-molecular-weight polymer product, where the oligomer fragments and end-group of such product were characterized by MALDI-TOF. On low catalyst loading (6400:1), complex 1 with trifluoroacetate group is the most active in the copolymerization of CO2 with CHO to give highly productivity (TON>5,000) and molecular weight up to 52,000 g/mol.
Ni catalyst 1 leads to not only controlled CO2/CHO copolymerziation, but it has also been applied to catalyze the copolymerization of 4-vinyl-1,2-cyclohexene oxide (VCHO) and CO2 to obtain the corresponding polycarbonate with the vinyl functionality on the side chains. Finally, di-nickel catalyst 1 was also able to catalyze the copolymerization of cyclopentene oxide (CPO) and CO2 to afford the poly (cyclopentene carbonate)s with highly carbonate linkage contents.
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