A ratiometric fluorescent probe for selective detection of thiophenol derivatives

Though a number of on-off or off-on fluorescent probes have been developed for the detection of thiophenol by using its unique recognition groups, such as 2, 4-dinitrophenyl ether, 2, 4-dinitrophenyl sulfonamide, and 2, 4-dinitrophenyl sulfonate, up to now, there are few probes that can detect thiophenol by the proportional fluorescence signal. We developed a ratiometric fluorescent probe with coumarin pyridine derivative as fluorophore and 2, 4-dinitrophenyl ether moiety as the sensing unit which could be used to detect thiophenol derivatives by the aromatic nucleophilic substitution reaction. This probe (CPBPN) displayed significant change in fluorescence ratio (256 fold) to result in a more reliable analysis by self-calibration and a relatively low detection limit of 24 nM toward 4-methylthiophenol (MTP) within 30 min to achieve more sensitivity. Besides, the probe was also applied to detect the presence of thiophenol derivatives in actual water samples and fluorescence imaging in living cells. The present work is of great importance for monitoring environmental pollutants and studying their biological function.