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), {[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, and 4,4′-bpy = 4,4′-bipyridyl), were synthesized under solvothermal/hydrothermal conditions and structurally characterized via elemental analysis, IR spectroscopy, and single-crystal and powder X-ray diffraction. Compound 1 displays infinite 2D sheets, which stack 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 was assigned to a novel topological type, pkb9. Compound 2 shows a 3D assembly with the 3,4,6-connected topology sqc130. Compound 3 and 4 form interdigitated 3D supramolecular networks with a 4-connected sql/Shubnikov topology. Compound 5 shows an unusual 2D → 3D framework with a 3,8-connected tfz-d; UO3 topology. In compound 6, 2D → 3D packing was observed due to weak C–H⋯O interactions that aided in the formation of a 3D network with a 4-connected sql/Shubnikov topology. The luminescence properties of all the compounds in their solid state and as emulsions in various solvents were investigated using nitroaromatic compounds.