Chain, layer, and self-penetrated copper dipyridylamine coordination polymers with conformationally flexible ring-based dicarboxylate ligands

Abstract

Hydrothermal reaction of copper salts, 4,4′-dipyridylamine (dpa), and a conformationally flexible ring-based dicarboxylic acid has afforded a series of four new crystalline coordination polymer solids with different topologies and dimensionalities. {[Cu(c-14cdc)(dpa)]·H2O}n (1, c-14cdc=cis-1,4-cyclohexanedicarboxylate) shows interdigitated paddlewheel-dimer based [Cu(c-14cdc)]n chains with pendant dpa ligands. [Cu2(t-14cdc)2(dpa)]n (2, t-14cdc=trans-1,4-cyclohexanedicarboxylate) possesses {Cu4(OCO)6} linear tetrameric clusters linked into a very rare 8-connected ilc self-penetrated 3D net with 4245.63 topology. The chain coordination polymer {[Cu(t-14cdc)(dpa)(Hdpa)](NO3)·3.5H2O}n (3) was obtained as a minor product in the synthesis of 2. Use of a related dicarboxylate ligand with a rigid central ring and flexible carboxylate arms resulted in [Cu(1,4-phda)(dpa)]n (4, 1,4-phda=1,4-phenylenediacetate), which manifests a rippled (4,4) grid 2D net. Thermal properties of all new materials are presented. A variable temperature magnetic susceptibility study on 2 showed strong antiferromagnetic superexchange between the inner and outer copper atoms within the tetrameric clusters (g=2.19(2), J1=−154(2)cm−1, J2∼0cm−1).