Benzimidazole based ratiometric and colourimetric chemosensor for Ni(II).

A highly sensitive and selective benzimidazole based colourimetric chemosensor (HL) for the efficient detection of Ni(2+) has been reported. The synthesized chemosensor HL is highly efficient in detecting Ni(2+) over other metal ions that commonly coexist with Ni(2+) in physiological and environmental samples. HL also shows distinct color change from orange yellow to blue visible under the naked eye due to specific binding with Ni(2+). This color change corresponds to a large red shift of the UV-Vis spectrum from 403 nm to 600 nm with a distinct isosbestic point at around 500 nm. The cation sensing property of the receptor HL has been examined by UV-Vis spectroscopy. Electronic structure of the HL-Ni(2+) complex and sensing mechanism has been interpreted by DFT and TDDFT calculations.