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

Five new Ni-II/Cd-II/Co-II coordination polymers (CPs), namely [Ni(3-pna)(mip)].H2O (1), [Ni(3-pna)(mip) (H2O)].4H(2)O (2), [Cd-2(3-pna)(mip)(2)(H2O)].2H(2)O (3), [Cd(3-pna)(mip)](2).3H(2)O (4) and [Co(3-pna)(mip)].H2O (5) [3-pna = 3-pyridylnicotinamide, H(2)mip = 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 [M-2(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 Cd-4(COO)(4) subunits and mu(2)-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. (C) 2016 Elsevier Ltd. All rights reserved.