A novel imidazo[1,5-α]pyridine-based fluorescent probe with a large Stokes shift for imaging hydrogen sulfide

An imidazo[1,5-α]pyridine-based fluorescence probe NIPY-DNP with a large Stokes shift (193 nm) has been successfully developed for highly selective, sensitive and rapid detection of H2S. The selective deprotection of 2,4-dinitrophenyl ether group of NIPY-DNP by H2S led to a dramatic fluorescent enhancement (273-fold) at 505 nm within 5 min in PBS buffer solution. The sensing mechanism is proposed on the basis of the thiolysis reaction by H2S, which has been confirmed by HPLC and HRMS. The detection limit is 0.36 μM, which is superior to the other reported H2S probes. Additionally, cell imaging studies demonstrated that NIPY-DNP could be used to visualize H2S in living cells.