Syntheses, structures, and photoluminescence of three cadmium(II) coordination complexes based on pyridine-2,6-dicarboxylic acid and a derivative

Three Cd(II) coordination complexes based on two different pyridine dicarboxylic acids (pyridine-2,6-dicarboxylic acid (H2PDA) and its derivative 4-hydroxypyridine-2,6-dicarboxylic acid (chelidamic acid, H3CAM)), [Cd2(PDA)2(H2O)3]n (1), {[Cd2(HCAM)2(H2O)4]·3H2O}n (2), and [Cd4(HCAM)4(H2O)8] (3) have been isolated under hydrothermal conditions. Compound 1, with H2PDA and Cd(NO3)2·4H2O, exhibits a 1-D chain structure. Compound 2, obtained by using H3CAM instead of H2PDA, contains a different 1-D chain from that of 1. When using CdCl2·2.5H2O and H3CAM, a discrete tetranuclear Cd4 compound (3) was obtained, and the isolated molecules are expanded to a eight-connected CsCl-like topology with point symbol (424·64) through hydrogen bonding interactions. Furthermore, the photoluminescent properties of 1–3 were investigated.