Self-assembly of three novel mixed-ligand coordination polymers: Formation of 2-D grids, 1-D chains and ladders and crystal band structure

Abstract

Hydrothermal reaction of the carboxylate-based ligands with metal salts (or oxide) and 4,4′-bipyridine as a second linker, afforded three new coordination polymers, namely, [Co(PCPA) 2(4,4′-bpy)] n ( 1) with 2-D rectangle grids, Cu(PCPA) 2(4,4′-bpy)] n ( 2) with a linear chain, [Ag(PCPA)(PCPAH)(4,4′-bpy) · H 2O] n ( 3) with 1-D molecular ladder (4,4′-bpy = 4,4′-bipyridine; PCPA = p-chlorophenoxyacetate; PCPAH = p-chlorophenoxyacetic acid). It is noticeable that compound 3 is also a supramolecular framework built by coordination bonds, weak interactions between Ag ions, π–π stacking interactions and hydrogen-bonded interactions. The three compounds with different structure motifs have been characterized by elemental analyses, IR spectra, ultraviolet–visible diffuse reflection integral spectra, fluorescent spectra and single crystal X-ray diffraction analysis. Furthermore, the bonding properties of compound 3 were investigated in terms of the absorption spectrum, as well as the calculated band structures and density of states.