Molecular engineering of d-A-d-based non-linearity fluorescent probe for quick detection of thiophenol in living cells and tissues

Thiophenols are widely utilized for producing pesticides, polymers and pharmaceuticals. Studies have shown that prolonged exposure of human to thiolphenol can result in serious health problems such as significant damage of the central nervous system. Herein, we have developed a novel turn-on two-photon fluorescent probe TP-ASH for selective and sensitive detection of thiophenols. We first constructed a new two-photon dye by connecting a coumarin fluorophore and a naphthalene fluorophore through 2,5- disubstituted-1,3,4-oxadiazole ring to afford d -π-A-π- d -structure. Fluorescent studies showed that this new dye possess large two-photon active absorption across-section (250 GM) and high fluorescence quantum yield (0.85). Encouraged by the results, we proceeded to conjugate this novel dye to a thiophenol recognition moiety, 4-dinitrobenzene-ether (DNB). The resulting probe displayed high selectivity towards thiophenols over their similar analogues, aliphatic thiols. The probe also exhibited high sensitivity, with a detection limit of 6.7 nM and a fluorescence enhancement of 163-fold. In addition, we have successfully applied the probe for two-photon imaging studies of thiphenols in living cells and mice tissues. We envision that the probe will add useful tools in detecting thiophenols in environmental samples and biological systems.