A novel fluorescence turn-on coumarin-pyrazolone based monomethine probe for biothiol detection

A coumarin-pyrazolone monomethine based turn-on fluorescence ratiometric probe C-3 for selective detection of cysteine (Cys) and glutathione (GSH) is reported. It exhibits OFF-ON states and is more sensitive to GSH in aqueous solution neutral and basic pH. The ON state is due to the inhibition of intramolecular charge transfer (ICT) process between pyrrole and pyrazolone moieties.