Designing ancillary ligands for heteroleptic/homoleptic zinc complex formation: synthesis, structures and application in ROP of lactides

Abstract

Synthesis and characterization of a series of new amino-phenol/naphthol ligands (L^1,2-H) have been developed and their respective zinc complexes (1 and 2-Zn) have been synthesized. The molecular structures of L¹-H and 1, 2-Zn were explored in detail by NMR, single-crystal X-ray studies and DFT calculations, which confirmed the existence of complexes as stabile dimers both in a solution and in the solid state. All complexes mediate the ring-opening polymerization (ROP) of lactide highly efficiently, at room temperature, in a controlled fashion. The influence of the architecture of the ligand on the desired homo/heteroleptic complex formation, as well as the relationship between the initiator design and the catalytic activity have been investigated.