Supramolecular assemblies of copper(II)–pyridine-2,3-dicarboxylate complexes with N-donor ligands and clustered water molecules

Four new dinuclear and polynuclear Cu(II)–pyridine-2,3-dicarboxylate complexes with N-donor ligands, [Cu2(μ-pydc)2(dmim)4]·6H2O (1), {(4-mimH)2[Cu(μ-pydc)2]·2H2O}n (2), {[Cu(μ-pydc)(eten)]·2H2O}n (3) and {[Cu(pen)2Cu(μ3-pydc)2]·H2O}n (4) (pydcH2 = pyridine-2,3-dicarboylic acid, dmim = 1,2-dimethylimidazole, 4-mim = 4-methylimidazole, eten = N,N-diethylethylenediamine and pen = 1,3-diaminopropane) have been prepared by utilizing metalloligand approach in a two-stage synthesis and characterized by elemental analysis, FT-IR spectroscopy, thermal analysis and X-ray diffraction techniques. In 1, the dinuclear units are connected each other by cyclic discrete water tetramers to form a 2D hydrogen bonded supramolecular compound, which are extended into a three-dimensional network by C–H⋯π interactions. In 2, the adjacent 1D chains are connected by the water cluster to form a 2D layer structure. The 2D layers of 4 are further extended into 3D supramolecular network by only weak C–H⋯π interaction.