A Sensitive and Selective Fluorescent Thiol Probe in Water Based on the Conjugate 1,4-Addition of Thiols to alpha,beta-Unsaturated Ketones

Compound 1 was designed and synthesized as a new fluorescent thiol probe. Probe 1 was constructed on the basis of the conjugate 1,4-addition of thiols to alpha,beta-unsaturated ketones. Notably, probe 1 has suitable water solubility, which allows the sensing assay to be performed in water. Probe I is highly sensitive for thiols with a 211-fold fluorescence dynamic range and a low detection limit of 9.25 x 10(-7) M. The major features of probe 1 also include a high selectivity for thiols over other relevant biological species, excitation and emission in the visible region, rapid functioning at pH 7.4, and a good linear relationship between the fluorescence signal and the thiol concentration. Accordingly, these desirable characteristics may render probe 1 as potentially useful for biological applications.