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 (L-3) with Cd(II) in the presence of different pseudohalide anions [N-3(-), dca (dicyanamide) or SCN-] produce three distinct coordination polymers, i.e. {[Cd-5(L-3)(2)(H2O)(2)(N-3)(10)](CH3OH)(2)(H2O)(4)}(n) (1), [Cd(L-3)(2)(dca)(2)](n) (2) and [Cd(L-3)(2)(SCN)(2)](n) (3). In 1, the N-3(-) anions with three different coordination modes bridge the Cd(II) ions to form 2-D inorganic layers, which are extended by the tridentate L-3 ligands to result in a 3-D coordination framework. In 2 and 3, the anion (dca or SCN-) takes the terminal coordination and L-3 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. (C) 2011 Elsevier B.V. All rights reserved.