Diverse Cd(II) coordination polymers with a multidentate N-donor ligand 3,5-bis(4-pyridyl)-4-(3-pyridyl)-1,2,4-triazole and pseudohalide anions

Assemblies of 3,5-bis(4-pyridyl)-4-(3-pyridyl)-1,2,4-triazole (L3) with Cd(II) in the presence of different pseudohalide anions [N3−, dca (dicyanamide) or SCN−] produce three distinct coordination polymers, i.e. {[Cd5(L3)2(H2O)2(N3)10](CH3OH)2(H2O)4}n (1), [Cd(L3)2(dca)2]n (2) and [Cd(L3)2(SCN)2]n (3). In 1, the N3− anions with three different coordination modes bridge the Cd(II) ions to form 2-D inorganic layers, which are extended by the tridentate L3 ligands to result in a 3-D coordination framework. In 2 and 3, the anion (dca or SCN−) takes the terminal coordination and L3 acts as the bidentate bridge, resulting in 1-D double-strand chain for 2 and double-strand chiral helix for 3. Thermal stability and fluorescence for 1–3 are also presented.