Reactivity Modulation of Benzopyran-Coumarin Platform by Introducing Electron-Withdrawing Groups: Specific Detection of Biothiols and Peroxynitrite.

A variety of fluorophores have been designed and created to fabricate organic fluorescent probes. Among these fluorophores, benzopyran-coumarin (BC) based fluorescent platform has attracted increasing attention as it shows multiple appropriate fluorescent and imaging capacities. Nevertheless, the analytical potential of BC is still urgently needed to be further excavated as its detection performance is hindered by the inherent drawbacks of current BC skeleton, that is, limited number of reactive sites. As such, in this work, by simply introducing electron-withdrawing (EW) substituent groups, we reconstructed BC skeleton to afford two fluorescent probes, BCB (-Br substitued) and BCN (-NO2 substitued), both of which featured two highly reactive sites. These two probes were capable of detecting peroxynitrite (ONOO-) and biothiols (hydrogen sulfide, glutathione, cysteine, and homocysteine) through naked eye and UV-vis absorption analysis in buffer solution. In addition, BCB was able to specifically sense biothiols with fluorescent analysis while BCN, with - NO2 instead of -Br, displayed more prominent fluorescent specificity toward ONOO-. This work provided a new strategy for the reactivity regulation of fluorophore through EW group introduction, as well as an alternative approach and method for the construction of fluorescent probes for other important biological species.