Multinuclear alkylaluminium macrocyclic Schiff base complexes: influence of procatalyst structure on the ring opening polymerisation of ε-caprolactone

摘要

Two remote dialkylaluminium centres supported by a macro-cyclic Schiff base ligand exhibited beneficial cooperative effects, whilst aluminoxane-type bonding proved to be detrimental to activity for the ring opening polymerisation of ε-caprolactone.rnPoly(lactide) and poly(s-caprolactone) are amongst the most studied and desirable biodegradable polymers due to their biomedical applications and their potential as alternatives to well-established, non-degradable poly(olefin)s.rnDinuclear catalysts have attracted recent attention in the field of the ring opening polymerisation (ROP) of cyclic esters and epoxides due to the possible cooperative effect that can occur between metal centres linked through M-O-M' type bonds. In particular, reports have shown dinuclear organoaluminium species to be highly active for the ROP of e-caprolactone and lactide; however, structural and catalytic studies on multinuclear aluminium complexes and, consequently, observations of cooperative effects and motifs which promote them are scant.