Synthesis, characterisation and ROP catalytic evaluation of Cu(II) complexes bearing 2,2ʹ-diphenylglycine-derived moieties

Abstract

The treatment of CuX2 (X = Cl, Br) with an equimolar amount of 2-2ʹ-diphenylglycine (DpgH) in EtOH at reflux afforded, after work up, the complexes [CuCl(Dpg)(EtOH)]2 (1) and [(CuBr2)2(Dpg)2Cu(EtOH)4] (2), respectively. The compounds were obtained microanalytically pure in low to moderate yield (13 and 27%, respectively) and were fully characterised. Synthetic attempts towards Cu-alkoxide species led to the isolation of the heterobimetallic species [(CuCl2)(Dpg)Li(THF)]·THF (3·THF). Finally, complex 4, bearing an imine ligand derived from the decarboxylation of DpgH, was serendipitously obtained from the synthesis of 3. These complexes were found to be inactive in the homo- and co-ring opening polymerization (ROP) of cyclic esters (ε-caprolactone and rac-lactide) and epoxides (propylene oxide and cyclohexene oxide). Compounds 1 and 2 were shown to be non-toxic against cancerous cell lines HCT116 and HT-29.