A 2,3-diphenyl-5,6,7,8-tetrahydroquinoxaline based potential optical chemosensor for detection of Ni2+ ions: anticancer activity and biosensor imaging

Abstract

A reversible fluorescent and colorimetric 2,3-diphenyl-5,6,7,8-tetrahydroquinoxaline based mono-Schiff base receptor (L) for the detection of Ni²⁺ in aqueous medium has been developed for the first time. L has been characterised by FTIR, ¹H-NMR, ESI-MS, elemental analysis, X-ray single crystal analysis and DFT studies. Receptor L exhibits an excellent selective and rapid fluorescence and colorimetric response towards Ni²⁺. The sensitivities of the fluorescence based assay (3.9 × 10⁻⁷ M) and colorimetric assay (4.95 × 10⁻⁷ M) for Ni²⁺ are sufficiently low in comparison to the previously reported literature values. From the Job plot measurement and the ESI-MS spectrum, 2 : 1 stoichiometric complexation between L and Ni²⁺ has been established. Receptor L shows remarkable detection ability in a wide pH range of 4–9 and it has been successfully utilised in the determination of Ni²⁺ in various aqueous solutions of real samples. At the specified doses and incubation times, L can be used as an anticancer drug and a selective sensor for bio-imaging of Ni²⁺ ions without having any cytotoxic effects.