Synthesis, structure, and physical properties of a new anions-controlled Cd(II)-guanazole (3,5-diamino-1,2,4-triazole) hybrid family

Nine members of a new anions-controlled Cd(II)-guanazole (3,5-diamino-1,2,4-triazole=Hdatrz) hybrid family, that is, Cd3(datrz)6(H2O)2] (1), Cd3(datrz)4F2] (2), Cd5(datrz)4Cl4(OH)2] (3), Cd5(datrz)4Br4(OH)2] (4), Cd3(datrz)2(SO3)2].(H2O) (5), Cd3(datrz)2(O2CMe)4] (6), Cd(datrz)(O2CEt)] (7), Cd(Hdatrz)(O2CtBu)2] (8), and Cd(Hdatrz)2(H2Edta)] (9) have been synthesized by exploiting hydrothermal reactions of guanazole with suitable cadmium salts under appropriate reaction conditions. With effective control of inorganic or organic anions, the coordination diversity of the guanazole ligand in 1-9 manifests an unprecedented enrichment with five bridging modes varying from bidentate to quadridentate, two of which are first reported. Compound 1 is the first reported three-dimensional chiral complex constructed from the guanazole ligand which adopts a novel N1, N2, amino N-bridging mode. Halogen anions F-, Cl-, and Br- controlled compounds 2-4 are all three-dimensional, with their guanazole ligands possessing another novel quadridentate bridging mode. Sulfite anions controlled compound 5 displays a three-dimensional network with peculiar cage-like hexnuclear cadmium clusters. As for organic anions, low dimensional structures have been found for alkylcarboxylate anions MeCO2-, EtCO2-, and tBuCO2- controlled compounds 6, 7, and 8 (two-dimensional) and for H2Edta2- controlled compound 9 (zero-dimensional), and their guanazole ligands manifest low coordination numbers as well. These hybrid materials also present interesting structure-induced physical properties. The chiral compound 1 exhibits the second-order nonlinear optical properties at room temperature. Compounds 2-9 except 6 all exhibit photoluminescence of blue fluorescent emissions in the solid state at ambient temperature, which may be assigned to the intraligand pi-pi* transitions. Some structure related red or blue emission shifts have been investigated. Thermal studies show that most compounds of this study possess a high thermal stability.