A novel ratiometric sensor for the fast detection of palladium species with large red-shift and high resolution both in aqueous solution and solid state

A highly selective fluorescent probe (OHBT) was designed and synthesized by linking the ESIPT fluorophore N-(3-(benzo[d]thiazol-2-yl)-4-(hydroxyphenyl) benzamide) (HBTBC) to the palladium specificity response group, allyl group, for the detection of palladium species in aqueous solution. The allyl group can be hydrolyzed by Pd⁰ species through the Pd⁰-catalyzed Tsuji-Trost reaction and thus release the fluorophore HBTBC, which shows two emission bands. The maximum emission spectra originated from the enol and keto forms at 415 and 555nm respectively and with no overlap, which implies the high resolution of the palladium detection. The palladium species can also be detected by paper strip because of the solid-state fluorescence of probe HOBT catalyzed by palladium. This method was successfully applied in the palladium related Suzuki-Miyaura coupling reaction and the detection limit is lower than 1μM.