A highly selective ratiometric fluorescent probe for H2S based on new heterocyclic ring formation and detection in live cells

A 3-indolylacrylate derivative, 3-IA, prepared by connecting an ethyl acrylate in 3-position of indole has been synthesised and characterised. Ethyl acrylate moiety acts as the Michael acceptor towards H2S, and the resultant addition product then participates in intramolecular cyclisation with the ester group at 2-position to form another new heterocyclic ring. Blue fluorescence of 3-IA turned into green in presence of H2S, leading to ratiometric behaviour of the fluorescent sensor with large stokes shift of 55 nm. Probe 3-IA has excellent selectivity towards H2S over other biothiols and other competing anions. Density function theory/time-dependent density function theory calculations were carried out to validate the reaction mechanism and the electronic properties of 3-IA. Importantly, the ratiometric probe 3-IA shows great promise in H2S detection by simple visual fluorescent inspection in filter paper-based protocol. The probe shows its excellent ability to detect H2S in different natural water samples. Furthermore, we have employed our probe to detect H2S for ratiometric imaging in live Vero cell. [GRAPHICS] .