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

Six novel Cd(II) coordination polymers based on 4,4′-bis(1,2,4-triazol-1-ylmethyl)biphenyl (btmb), namely, [Cd(btmb)2I2]n (1), [Cd(btmb)I2]n (2), {[Cd(btmb)2(NO3)2]·H2O}n (3), {[Cd(btmb)2(SCN)2]·3H2O}n (4), {[Cd(btmb)(CH3COO)2(H2O)]·CH3CN}n (5) and [Cd(btmb)Cl2(H2O)]n (6) have been synthesized by the reactions of btmb with Cd(II) salts in the presence of different anions (I−, NO 3 - , NCS−, CH3COO− or Cl−) under appropriate reaction conditions. The assemblies of btmb with CdI2 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(NO3)2·4H2O gives rise to a 2D grid network structure 3 which is similar to 1. When the I− or NO3− anions were replaced by NCS−, CH3COO− 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.