Metal-organic framework structures of Cu(II) with pyridine-2,6-dicarboxylate and different spacers: identification of a metal bound acyclic water tetramer

Abstract

The ligand pyridine-2,6-dicarboxylic acid (pdcH₂) reacts under hydrothermal conditions, with Cu(NO₃)₂·6H₂O in the presence of different N-heterocycles used as spacers to form 1D, 2D or 3D metal-organic framework structures depending on the nature of the spacer. These network structures are characterized by X-ray crystallography, variable temperature magnetic measurements, powder X-ray diffraction, infrared and thermal gravimetric analyses. With 4,4'-bipyridine spacer, a 2D network is formed where every alternate Cu(II) ion in the chain is coordinated terminally to an acyclic tetrameric water cluster.