Synthesis, characterization of aluminum complexes supported by multidentate aminophenol ligands and application in the ring-opening polymerization of ε-caprolactone

The reactions of H4L1 (L-1 = N-1,N-1,N-2,N-2-tetra((2-hydroxy-3,5-dibutyl)benzyl)-1, 2-ethanediamine) and H4L2 (L-2 = N-1,N-1,N-2,N-2-tetra((2-hydroxy-3,5-dimethyl)benzyl)-1,2-ethanediamine) with AlMe3 in toluene give [Al-2(CH3)(2)L-1(THF)(2)] (1) and[Al-2(CH3)(2)L-2] (3) respectively. Treatment of complex 1 with 2-methoxyethanol affords [Al-2(OCH2CH2OCH3)(2) L-1] (2). The experimental results indicate that complexes 1 and 2 can efficiently initiate the ring-opening polymerization of epsilon-caprolactone under a controlled manner, yielding polymers with relatively narrow molecular weight distribution and desirable molecular weights, while the performance of dinuclear complex 3 is not good due to the side reactions between the two neighboring active groups in the propagation progress. (C) 2013 Elsevier B.V. All rights reserved.