A large stokes shift fluorescent probe for sensing of thiophenols based on imidazo[1,5-α]pyridine in both aqueous medium and living cells.

An imidazo [1,5-α]pyridine-based fluorescent probe MIPY-DNP with a large Stokes shift (173 nm) for the sensing of thiophenols in aqueous medium has been developed. This probe with 2,4-dinitrophenyl ether as a highly thiophenol-selective group was constructed based on the combination of PET and ESIPT mechanisms. Upon the treatment with thiophenols, MIPY-DNP produced a remarkable fluorescence enhancement (209-fold) at 478 nm. The detect limit for thiophenols was calculated to be as low as 5.6 nM. Importantly, the practical utility of MIPY-DNP for the selective detection of thiophenols has been successfully demonstrated in both real water samples and living cells.