Transition metal coordination polymers based on imidazole/triazole carboxylic acid ligands for efficient detection of Fe3+ions and adsorption of dyes

Five new coordination polymers (CPs), namely [Zn(L1)2 & sdot;(H2O)2]n (1), [Cd(L1 )2(H2O)2]n (2), [Cd(L1)Cl]n (3), [Cu (L1 )2(H2O)2]n (4) and [Cd(L2 )2(H2O)2]n (5) [HL1 =4-(((1H-1,2,4-triazol-3-yl)amino)methyl)benzoic acid, HL2 =4-((4-(1H-imidazol-1-yl)benzyl)amino)benzoic acid] based on imidazole/triazole carboxylic acid ligands were synthesized by adjusting the structure of the ligands, synthesis temperatures and solvents. CPs 1, 2, 4 and 5 display 1D chain structures with different shapes, and 3 is a 4-connected crb network structure. The fluorescence sensing properties and dye adsorption of those CPs were studied, the results showed that 1-3 can sensitively detect Fe3+ by turn-off effect and the limits of detection were 0.269, 0.024 and 0.06 mu M, respectively. The study of the mechanism showed that energy transfer, competitive absorption and weak interaction are the reasons of fluorescent quenching. CP 5 exhibited adsorption performance for malachite green (MG) with adsorption capacity of 1428.6 mg g- 1 and has good reusability, and the hydrogen bond and pi-pi interactions have been proved to be the main factors for the adsorption of MG by 5.