3D supramolecular networks based on hydroxyl-rich Schiff-base copper(II) complexes

Abstract

Reactions of the Schiff base ligand OH-C6H4-CHNC(CH2OH)3 (H4L) with copper(II) salts in various reaction media afforded complexes [Cu4(H2L)4]·MeOH (1·MeOH), [Cu2(O2CMe)2(H3L)2] (2), [Cu4(H2L)4(H2O)2]·1.5dmf (3·1.5dmf), [Cu4(H2L)4(H2O)]·MeOH (4·MeOH) and [Cu4(H2L)4]2·2H2O·7MeOH (5·2H2O·7MeOH). Compounds 1, 3 and 4 consist of neutral tetranuclear entities in which the CuII ions are coordinated by the tridentate Schiff base ligands, forming a tetranuclear Cu4O4 cubane-like configuration. Compound 5 contains similar cubane-like tetranuclear entities which are further linked through the hydroxyl groups of the ligands thus forming dimers of cubanes. Compound 2 contains a neutral dinuclear entity in which the CuII ions are bridged through the Schiff base and the acetate ligands, comprising distorted Cu2O2 core. The Schiff base ligand adopts five different coordination modes and two deprotonation states in the structures of 1–5 acting simultaneously as chelating and bridging agent between the metal ions. The lattice structures of 1–5 exhibit interesting 3D networks based on hydrogen bonded metal clusters and they are studied with Hirshfeld Surface analysis methods.