Interplay of coordinative and supramolecular interactions in directing the crystal structures of copper(II)-ofloxacin complexes under co-ligand intervention

Assemblies of ofloxacin (Hoflo) with Cu(II), in the presence of the organonitrogen ligands, such as 2,2'-bipyridyl (bpy), 4,4'-dimethyl-2,2'-bipyridine (dmbpy), and 8-hydroxyquinoline (hq), under similar conditions, yield a series of three coordination complexes, [Cu(oflo)(bpy)(H2O)](ClO4)(H2O)(1.5) (1), [Cu(Hoflo)(dmbpy)(ClO4)](ClO4)(H2O)(2) (2), and [Cu(oflo)(hq)](ClO4)(H2O)(2) (3). All three complexes have been structurally determined and characterized by physico-chemical and spectroscopic methods. All of the Cu(II) atoms adopt the similar square pyramidal coordination geometries. However, when considering the longer Cu-O contacts in 2, its coordination geometry turns out to be distorted octahedral and a binuclear motif is afforded. The results reveal that, distinct extended network architectures of 1D (for 1) and 2D (for 2 and 3) are further constructed with the aid of weak secondary interactions of H-bonding and aromatic stacking, by introducing various heterocyclic co-ligands. The thermal stabilities of the complexes are described and discussed.