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] (1)
and [Ca2(btc)­(pzc)­(H2O)3] (2) (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 1 is a three-dimensional framework consisting of helical chains
of calcium coordination polymers, while that of compound 2 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.