Thioacetalized coumarin-based fluorescent probe for mercury(II): ratiometric response, high selectivity and successful bioimaging application.

Taking advantage of the special Hg 2+ -promoted deprotection reaction of dithioacetals and the well-known coumarin chromophore, novel reactive fluorescent probes ( C3 and C4 ) towards mercury ions were designed and synthesized. Upon the addition of mercury ions, probe C3 displayed remarkable fluorescence quenching, which was beneficial to the production of a high signal output during sensing process. Differently, compound C4 displayed dramatic red-shift in both fluorescence (60 nm) and absorption (60 nm) spectra, with the detection limit of 90 nM. By virtue of this unique chemical reaction, compound C4 had selective response towards Hg 2+ over other metal ions and only the addition of Hg 2+ could lead to apparent emission and absorption spectra changes. Moreover, C4 was successfully applied to microscopic imaging for the detection of Hg 2+ in HeLa cells with ratiometric fluorescent methods. [ABSTRACT FROM AUTHOR]