Unusual 1D Tape of Pentameric and Tetrameric Water Clusters Trapped in a 2D Cobalt(II) Coordination Polymer: Synthesis, Characterization, and Catalytic Properties

Abstract

1D tape of pentameric and tetrameric water clusters have been observed in a complex of [Co(oba)(H2O)3]·(H2O)2·(dmbpy)]n (1), (H2oba = 4,4′-oxybis(benzoic acid), dmbpy = 2,2′-dimethyl-4,4′-bipyridine), which has been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), powder X-ray diffraction and single-crystal X-ray diffraction. In 1, a cyclic pentamer formed by four water molecules and one carboxylate oxygen, as well as a chain-like tetrameric water-(carboxyl oxygen) cluster are observed. The uncoordinated carboxylate oxygen atoms of oba anions, water molecules and free dmbpy ligands interact via hydrogen bonds forms a tape in which the dmbpy ligands point alternately up and down, and extend 2D 1 into a 3D supramolecular structure. Moreover, 1 has a remarkable activity for degradation of methyl orange in a photo-assisted Fenton-like process.