Supramolecular architectures of cadmium(II) built of 2,2′-biimmidazole and bifunctional carboxylates: Syntheses, crystal structure and properties

Hydrothermal method instead of conventional solution synthesis was employed in this contribution, which led to the desired insoluble carboxylate-coordinated complexes {[CdBr(H2biim)(PyCO2)(H2O)](H2O)}∞ (1) (H2biim = 2,2′-biimidazole, PyCO2 = isonicotinate), and [Cd(H2biim)2(HBDC)2] (2) (H2BDC = terephthaic acid), as major products. Interestingly, the soluble carboxylate-uncoordinated compounds [Cd(H2biim)2(H2O)2](BDC) (3) and [Cd(H2biim)2(H2O)2](PyCO2)2 · 4H2O (4) were also formed as minor products from the reaction solutions, clearly indicative of thermodynamic nature of the reactions. These compounds have been characterized by X-ray crystallography, IR, fluorescence spectra and thermogravimetric analysis.