Syntheses, structures and luminescence of a series of Cd(II)-containing coordination polymers constructed from a long flexible bis-triazole ligand

Abstract

Six novel Cd(II) coordination polymers based on 4,4′-bis(1,2,4-triazol-1-ylmethyl)biphenyl (btmb), namely, [Cd(btmb) 2I 2] n ( 1), [Cd(btmb)I 2] n ( 2), {[Cd(btmb) 2(NO 3) 2]·H 2O} n ( 3), {[Cd(btmb) 2(SCN) 2]·3H 2O} n ( 4), {[Cd(btmb)(CH 3COO) 2(H 2O)]·CH 3CN} n ( 5) and [Cd(btmb)Cl 2(H 2O)] n ( 6) have been synthesized by the reactions of btmb with Cd(II) salts in the presence of different anions (I −, NO 3 - , NCS −, CH 3COO − or Cl −) under appropriate reaction conditions. The assemblies of btmb with CdI 2 afford two different structures: two-dimensional (2D) rhombohedral grid layer network structure 1 and 2D layer structure 2 involved with one-dimensional (1D) linear cadmium chains. Treatment of btmb with Cd(NO 3) 2·4H 2O gives rise to a 2D grid network structure 3 which is similar to 1. When the I − or NO 3 − anions were replaced by NCS −, CH 3COO − or Cl −, different 1D coordination polymers 4– 6 were obtained, respectively. Polymer 4 displays a 1D double-chain structure, while both polymers 5 and 6 show 1D zigzag chain structures. In addition, the luminescence measurements reveal that polymers 1– 6 exhibit different fluorescent emissions in the solid-state at room temperature, which can be attributed to the various coordination environments of Cd(II), solvent molecules and different packing interactions in these polymers.