Syntheses, structures, photoluminescence, and magnetism of a series of 3,5-di(3,4-dicarboxylphenyloxy)benzoate-based complexes tuned by N-donor co-ligands and transition metal ions

Abstract

Six transition metal–organic complexes based on 3,5-di(3,4-dicarboxylphenyloxy)benzoic acid (H5L) and different N-donor co-ligands, namely, Cu(H3L)(2,2′-bpy)·H2O (1), Zn2(HL)(2,2′-bpy)2 (2), Cd2(HL)(2,2′-bpy)2(H2O) (3), Cd2(HL)(phen)4·5H2O (4), Cu(H3L)(phen) (5), and Cu(H3L)(4,4′-bpy)·H2O (6) (2,2′-bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, 4,4′-bpy = 4,4′-bipyridine), were successfully synthesized under hydrothermal conditions. Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR, powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). Complexes 1 and 5 possess discrete zero-dimensional (0D) structures which are further assembled into three-dimensional (3D) supramolecular frameworks by hydrogen-bonding interactions and π–π stacking interactions. Complexes 2 and 3 display similar 3D frameworks with different topologies. Complex 4 shows a one-dimensional (1D) chain which is further connected into a two-dimensional (2D) supramolecular layer via π–π stacking interactions. Complex 6 exhibits a 1D chain which is further extended into a 3D supramolecular network through hydrogen-bonding interactions. The H5L ligand is partially deprotonated in 1–6. The N-donor co-ligands and transition metal ions have important effects on the architectures of 1–6. The photoluminescent properties of 2–4 and the magnetic properties of 1 and 6 were also studied.