Effect of solvents and metal ions on the structural diversity of coordination polymers based on a dipyridylamide ligand: Construction, fluorescent and photocatalytic properties

Abstract

Five new NiII/CdII/CoII coordination polymers (CPs), namely [Ni(3-pna)(mip)]·H2O (1), [Ni(3-pna)(mip)(H2O)]·4H2O (2), [Cd2(3-pna)(mip)2(H2O)]·2H2O (3), [Cd(3-pna)(mip)]2·3H2O (4) and [Co(3-pna)(mip)]·H2O (5) [3-pna=3-pyridylnicotinamide, H2mip=5-methylisophthalic acid], have been hydrothermally or solvothermally synthesized. These complexes were characterized by IR spectroscopy, thermal analysis and single-crystal X-ray diffraction. Complexes 1–5, based on the same dipyridylamide (3-pna) and dicarboxylate (mip) ligands but using different solvent systems and metal ions, exhibit various structures. Complexes 1 and 5 feature isostructural 2D networks, which are very similar to that of 4. Their structures contain [M2(COO)2-(3-pna)2]n (M=Ni, Cd or Co) ladder-like double chains. Complex 2 displays a 2D 4-connected grid structure consisting of 1D [Ni-3-pna]n and [Ni-mip]n chains. Complex 3 presents a new 3D framework constructed from Cd4(COO)4 subunits and μ2-bridging 3-pna ligands. The versatile structures reveal the remarkable impact of the solvent systems on the architectures. Furthermore, the fluorescent behaviors of 3–4 and the photocatalytic properties of 1–5 under UV irradiation have been studied.