Molecular self-assembly of cadmium-triazolate complexes via hydrogen bonding: Synthesis, structures and photoluminescent properties

Abstract

Two new cadmium coordination polymers namely [Cd(HAmTrz–COO) 4 (NH 4 + ) 2 ] 1; and [Cd(HAmTrz) 2 I 2 ] n 2; (HAmTrz–COOH = 3-amino-1,2,4-triazole-5-carboxylic acid), have been prepared based on HAmTrz–COOH as ligand. The crystal structures of 1 and 2 have been determined by single-crystal X-ray diffraction technique. In coordination-complex 1 four triazole ligands coordinate via N1 nitrogen leading to a tetrahedral geometry around cadmium ion, while in 2 the ligand prefers to coordinate to the metal in a bidentate bridging mode. The structures of both the coordination polymers can be envisaged as 3D hydrogen bonded networks. Thermogravimetric analysis shows that 2 is more stable than 1 owing to different coordination numbers of cadmium atoms. Photoluminescence properties of both the compounds have been investigated in the solid state. The synthesis of two new cadmium coordination polymers namely [Cd(HAmTrz–COO) 4 (NH 4 + ) 2 ] 1 ; and [Cd(HAmTrz) 2 I 2 ] n 2; (HAmTrz–COOH = 3-amino-1,2,4-triazole-5-carboxylic acid) have been accomplished via variations in the reaction conditions. Both the compounds self-assemble into 3D hydrogen bonded networks assisted by supramolecular synthons. Thermal and photoluminescence properties have been examined in the solid state. ► In both the polymeric structures, hydrogen bonds working in cooperativity with covalent interactions are capable of ‘maneuvering’ complex ions into desirable motifs. ► These are one of a few d 10 transition metal coordination polymers where phenomenon of cooperativity of hydrogen bonding is very prominently manifested in the robustness of the overall framework structures.