Benzil-Dihydrazone Based Bis-Schiff Base Dual-Sensor for Expeditious Colorimetric Detection of Ni2+ and Fluorometric Detection of Ag+: Environmental and Biological Applications.

In this research, a novel dual chemosensor L has been reported. It has been characterised by FTIR, 1H-NMR, ESI-MS, elemental analyses, X-ray single crystal analysis and DFT studies. In a 1:1 methanol-water medium (v/v), the receptor L detected Ni2+ with color change from colorless to yellow and Ag+ with turn-on fluorescence enhancement. UV-vis spectroscopy, fluorescence titration, FTIR and ESI-MS have been used to analyse the response mechanisms of fluorescent colorimetric sensing. The colorimetric sensitivity for Ni2+ is 3.0 × 10-7 M and fluorometric sensitivity for Ag+ is 7.2 × 10-7 M; both the values are sufficient below the WHO permissible limits in aqueous solution. From the Job's plot measurements and the ESI-MS spectrum, 2: 1 stoichiometric complexation between L and Ni2+/Ag+ has been established. Receptor L shows remarkable detection ability in a wide pH range of 4-9 and can be successfully applied for the detection and quantification of Ni2+ ions in environmental samples, and Ag+ ions in BSA protein. At the specified doses and incubation times, L can be used as an anticancer drug and a selective sensor for bio-imaging of Ag+ ion without having any cytotoxic effects.