Conformation-switched chemosensor for selective detection of Hg2+ in aqueous media

A conformation flexible chemosensor for selective detection of Hg2+ in aqueous media was achieved by incorporating two well-known rhodamine-6G dyes and a ferrocene group within one molecule. Distinguished from the monosubstituted ferrocene derivative which is previously reported a lack of interaction with Hg2+, the title compound was characteristic of two-armed bidendate binding unit. The Hg2+ sensing behavior can be switched via the conformation flexibility. The 1:1 sensor/Hg2+ binding mode was proposed and supported by the titration experiment and ESI mass spectrum. The fluorescent sensor can display a highly selective response of fluorescence enhancement toward Hg2+ and detect the parts per billion (ppb) level of Hg2+ in aqueous environment.