Synthesis and Characterization of Two- and Three-Dimensional Calcium Coordination Polymers Built with Benzene-1,3,5-tricarboxylate and/or Pyrazine-2-carboxylate

Two new calcium coordination polymers, [Ca₃(btc)₂(H₂O)₁₂] (<b>1</b>) and [Ca₂(btc)­(pzc)­(H₂O)₃] (<b>2</b>) (btc = benzene-1,3,5-tricarboxylate, pzc = pyrazine-2-carboxylate), have been synthesized using the hydro/solvothermal method and have been characterized using X-ray diffraction, IR, UV–vis, thermogravimetric analysis, and fluorescence analysis. The structure of compound <b>1</b> is a three-dimensional framework consisting of helical chains of calcium coordination polymers, while that of compound <b>2</b> is a double layered network in which the inorganic zigzag chains of calcium coordination polyhedra are linked by organic ligands. Both compounds show blue fluorescence when excited with UV light. Density functional theory calculations on electronic absorption spectra of organic ligands and calcium coordination polymers are discussed