Anion-directed assembly of cadmium(II)–dicyanamide coordination polymers based on a tripyridyltriazole ligand

Abstract

Assemblies of a tripyridyltriazole ligand, 3,4-bis(2-pyridyl)-5-(3-pyridyl)-1,2,4-triazole (L223) with dicyanamide (dca) anion and different Cd(II) salts in CH3OH–H2O media afford four coordination polymers, namely {[Cd2(L223)2(dca)4(H2O)](H2O)4}n (1), {[Cd(L223)(dca)(ClO4)](H2O)0.25}n (2), and [Cd(L223)(dca)X]n (X−=Cl− for 3 and Br− for 4). All complexes were structurally determined by single-crystal X-ray diffraction. In 1 and 2, the Cd(II) centers are combined by L223 spacers to form [Cd2(L223)2] bimetallic subunits, which are bridged by dca anions to result in the 1D motif and 2D layer, respectively. Complexes 3 and 4 display isostructural 3D homochiral coordination networks that are constructed by 1D [Cd(L223)]n helical subunits and dca bridges. These results indicate that the counter anions of Cd(II) salts will be responsible for the diverse structures of coordination polymers 1–4. Their solid state properties such as thermal stability and fluorescence will also be presented.