Cd(ii) coordination polymers constructed with a flexible carboxylate linker and pyridyl co-linkers: variation in the network topologies and photoluminescence properties

Abstract

Six new coordination polymers (CPs) of Cd(II) ion, {[Cd3(L)2(H2O)5(µ-H2O)]∙6H2O}n (1), {[Cd3(L)2(4,4′-bpy)3(H2O)2]∙4(H2O)∙(DEF)}n (2), {[Cd(HL)(dpe)0.5(H2O)]2∙(H2O)}n (3), {[Cd(HL)(dpd)0.5(H2O)]}n (4), {[Cd(HL)(1,2-dpe)0.5]}n (5), and {[Cd3(L)2(1,3-dpp)2]∙3H2O}n (6), (where H3L = 5-(2-Carboxybenzyloxy)isophthalic acid, 1,3-dpp = 1,3-di(4-pyridyl)propane, 1,2-dpe = 1,2-di(4-pyridyl)ethane, dpd = 1,2-di(pyridin-4-yl)diazene, dpe = 1,2-di(4 pyridyl)ethylene, 4,4′-bpy = 4,4′-bipyridyl) have been synthesized under solvothermal/hydrothermal condition and structurally characterized by elemental analysis, IR spectra, single-crystal and powder X-ray diffraction. Compound 1 displays an infinite 2D sheet which stacks upon each other to form a supramolecular 3D network. Topologically, the network can be viewed as a 3,3,3,5- connected four nodal net which is assigned to a novel topological type, pkb9. Compound 2 shows a 3D assembly with 3,4,6-connected topology sqc130. Compound 3 & 4 form interdigitated 3D supramolecular networks with 4-connected sql/Shubnikov topology. Compound 5 shows an unusual 2D → 3D framework with a 3,8-connected tfz-d; UO¬3 topology. In compound 6, 2D → 3D packing observed with the help of weak C-H•••O interactions to form a 3D network with 4-connected sql/Shubnikov topology. The luminescence property of all the compounds in the solid states and their emulsions in various solvents were tested with nitroaromatic compounds.