Synthesis and characterization of Zn(II) and Cu(II) complexes bearing (chiral substituent)(diethyl)-ethanediamine derivatives as precatalysts for rac-lactide polymerisation

摘要

A series of Zn(II) and Cu(II) complexes based on (chiral substituent)(diethyl)-ethanediamine derivatives, [LnMCl2] (where L-n = [(R)-N-1,N-1-diethyl-N-2-(1-phenylethyl)ethane-1,2-diamine] (L-A), [(R)-N-1-(1-cyclo-hexylethyl)-N-2,N-2-diethylethane-1,2-diamine] (LB) and 1N(1),NI-diethyl-N-2-(((1R)-6,6-dimethylbicyclo [3.1.1]hept-2-en-2-yl)methyl)ethane-1,2-diamine] (L-c)) were synthesised and characterised by X-ray crystallography. The isopropoxide derivatives, [L-n M((OPO)-P-1)(2)] generated in situ, effectively polymerised rac-lactide (rac-LA) and yielded heterotactic polylactide (PLA). The Cu(II) initiators exhibited better catalytic activities and mediated stereoselective ring-opening polymerisation (ROP) of rac-LA in a living manner to furnish PLA with higher heterotacticity compared with their Zn(II) analogous. The ROP activity of the current system largely relies on steric hindrance imposed by the substituents attached to the amine moiety of the (diethyl)-ethanediamine backbone. (C) 2018 Elsevier Ltd. All rights reserved.