One New Azo-azomethine Derivative for Detection of Ca۲+ and Cd۲+ Metal Ions: Synthesis, Characterization and DFT Studies

One new azo Schiff-base derivative: ۴-bromo-۱,۲-bis[۲-hydroxy-۵-(phenylazo)benzylideneamino]benzene (H۲L) was synthesized and characterized by common spectroscopic techniques and elemental analysis. The ability of the new chemosensor for detection of some main and transition metal ions was studied by UV-Vis spectroscopy in the mixture of DMSO: water (۹:۱). Upon addition of Ca۲+ and Cd۲+ ions, dramatic changes were observed in the UV-Vis spectrum of ligand (one new absorbance band appeared in the range of ۴۳۰- ۴۵۰ nm, while the absorbance band at ۳۵۱ nm disappeared). The stoichiometry of the complexes was determined using the Job method. The binding constants of Ca۲+ and Cd۲+ with receptor by Benesi-Hildebrand plots were found to be ۲.۸۷۴×۱۰۴ M-۱ and ۶.۴۴۵×۱۰۴ M-۱, respectively. The results indicated the receptor can recognize Ca۲+ and Cd۲+ ions from other cations in aqueous solution. Finally, the structure and electronic properties of the ligand and its complexes with Ca۲+ and Cd۲+ ions were analyzed by DFT and TD-DFT calculations.

Keywords:

Azo-azomethine ligand , UV-Vis spectroscopy , Chemosensor , DFT calculations