Synthesis and Structural Characterisation of Dinuclear Aluminium Complexes Supported by NNO-Tridentate Schiff-Base Ligands and Their Catalysis in the Ring-Opening Polymerisation of epsilon-Caprolactone

摘要

In this study, we prepared a series of dinuclear aluminium complexes {Bis{2-OAlMe2-3-CH=N[CH2CH2N(CH3)(2)]-5-CH3C6H2}CH2, Bis[2-OAlMe2-3-CH=N(2-PyCH2)-5-CH3C6H2]CH2, and Bis{2-OAlMe2-3-CH=N[2-N(CH3)(2)C6H4]-5-CH3C6H2}CH2} as well as their corresponding mononuclear aluminium compounds derived from NNO-tridentate Schiff-base ligands. The compounds were characterised by H-1 and C-13 spectroscopy and elemental analyses. Complexes 4 and 7 were additionally characterised by single-crystal X-ray diffraction. Their activities toward the ring-opening polymerisation (ROP) of epsilon-caprolactone (epsilon-CL) were investigated. In the presence of benzyl alcohol (BnOH), these complexes are catalytically active for the ROP of epsilon-CL. The kinetic studies for the polymerisation catalysed by these complexes indicated that the polymerisation was well controlled and produced polymers within a narrow molecular weight distribution. At low monomer concentrations, the catalytic activity of binuclear complexes is considerably greater than that of mononuclear complexes.