Investigation of thiolysis of NBD amines for the development of H2S probes and evaluating the stability of NBD dyes

In order to evaluate the thiolysis of NBD (7-nitro-1,2,3-benzoxadiazole) amines for development of H2S probes, herein we investigated the reactivity and selectivity of a series of NBD amines for the first time. The piperazinyl- and piperidyl-based NBD probes could react efficiently with micromolar H2S in buffer (pH 7.4), while such NBD(S) (nitrobenzothiadiazole) derivatives showed much slow thiolysis even in the presence of millimolar H2S. Low reactivity was also observed for thiolysis of these ethylamino-, ethanolamino- and anilino-based NBD probes. Therefore, almost all NBD amines used in bioimaging should be stable, in consideration of the presence of only micromolar endogenous H2S in vivo. Moreover, the piperazinyl-NBD derivatives could be efficient in the development of fluorescent H2S probes and for directly visualizing H2S by paper-based detection.