Preparation and characterization of four polymeric metal complexes based on the flexible ligand 1 H-1,2,4-triazole-1-propionic acid in different conformations

Three 2-D layered coordination polymers with (4,4) topology, {[Cu(trzp)(2)(H2O)]1.18H(2)O} (n) (1), {[Co(trzp)(2)(H2O)(2)]2H2O} (n) (2), and {[Cd(trzp)(2)(H2O)]2H2O} (n) (3), have been synthesized with the flexible, bifunctional ligand 1H-1,2,4-triazole-1-propionate (trzp(-)) as a two-connected bridge. In addition, a complicated 3-D MOF [Ag-3(trzp)(2)(NO3)] (n) (4) has been obtained with the help of AgAg interactions and trzp(-) as a four-connected linker. Htrzp and 1-4 have been characterized by single-crystal X-ray diffraction, elemental analysis, and infrared spectroscopy. The structural analysis showed that Htrzp has a gauche conformation in the solid state. However, both gauche and trans conformers of trzp(-) are observed in the crystals of 1; only one conformer of trzp(-) exists in the other three compounds (trans conformation in 2 and 3, and gauche conformation in 4). The thermal behaviors of 1-4 have been examined by thermal gravimetric analysis under nitrogen, which revealed that metal cyanide salts M(CN) (n) (M=Cu(II), Co(II), Cd(II), and Ag(I), n=1 or 2) may be an intermediate pyrolytic decomposition product of the corresponding compounds.