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−, NO3-, 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.

Graphical abstractSix novel Cd(II)-containing coordination polymers have been synthesized under appropriate reaction conditions. The structural diversities of the final products show that the reaction conditions and anions have important effects on the formation of coordination polymers. The fluorescence properties of the polymers are also investigated.Figure optionsDownload full-size imageDownload as PowerPoint slide