Syntheses and characterizations of two-dimensional supramolecular architectures based on hydrogen-bonded rectangular cavities

Two metal-organic coordination polymers, [Co(bpe)(H2O)2(Hdpa)2]n (1) and [Ni(bpe)(H2O)2(Hdpa)2]n (2), have been synthesized by the reactions of 1,2-bis(4-pyridyl)ethane (bpe), diphenic acid (H2dpa) with Co(NO3)2·6H2O and Ni(NO3)2·6H2O, respectively, in the presence of base. Single crystal X-ray diffraction analysis reveals that 1 and 2 are isostructural. Each of metal centers in 1 and 2 is coordinated in a slightly distorted octahedral geometry by two trans m-bpe nitrogen ligands, two trans carboxylate oxygen atoms from different Hdpa and two trans water molecules. Hdpa acts as a monodentate ligand through one carboxylate oxygen atom coordinating to a metal center, and its uncoordinated carboxylate oxygen atom and carboxylic group form a strong hydrogen bond, resulting in a one-dimensional chain containing rectangular hydrogen bonding rings. The bpe bridges adjacent chains generating two-dimensional layer architectures of 1 and 2, respectively. q 2004 Elsevier B.V. All rights reserved.