Syntheses and structures of four transition metal coordination polymers constructed from 2,2′-bipyridyl-4,4′-dicarboxylate

Abstract

Four transition metal(II) coordination polymers, [Mn(bpdc)(H2O)2] n (1), {Ni[(bpdc)(H2O)2]2H2O}n (2), [Ni(bpdc)(H2O)2] n (3), and [Cu(bpdc)H2O)] n (4) (bpdc2− = 2,2′-bipyridyl-4,4′-dicarboxylate), have been assembled from 2,2′-bipyridyl-4,4′-dicarboxylic acid and corresponding transition metal(II) salts under hydrothermal conditions. Single-crystal X-ray diffraction studies show that each metal ion in 1–3 is coordinated by two nitrogens of bpdc2−, two carboxylate oxygens from bpdc2−, and two waters to give a distorted octahedral geometry. Copper in 4 is coordinated by two nitrogens of bpdc2−, two carboxylate oxygens from bpdc2−, and one water to form a pyramid geometry. Compounds 1 and 3 are 3-D coordination polymers bridged by bpdc2−, while 2 and 4 exhibit 2-D layer structures bridged by bpdc2−; the layers are further assembled through hydrogen bonds to form 3-D supramolecular frameworks. Thermogravimetric analyzes of 1–4 show high thermal stability.