Benzimidazole-based imine-linked chemosensor: chromogenic sensor for Mg2+ and fluorescent sensor for Cr3+

We synthesized an imine-linked, benzimidazole-based chemosensor that can be used for chromogenic recognition of Mg2+ and fluorescent recognition of Cr3+. The chemosensor shows sensitive, selective, and ratiometric recognition of Cr3+ through concurrent quenching at one wavelength and enhancement of fluorescence intensity at another wavelength. It can also be used to detect Mg2+ via UV–vis absorption spectroscopy. DFT calculations support these phenomena. The sensor can be used to strain microbe cells without breakage.