A new fluorescence probe based on fluorescein-diarylethene fluorescence resonance energy transfer system for rapid detection of Cd2+

A novel diarylethene derivative 1O with fluorescein-quinoline unit was designed and synthesized successfully. Under the stimulation of light and chemical, the diarylethene molecule exhibited multi-responsive photoswitchable properties. Moreover, the compound was a potential ‘naked eye’ chemosensor with significant color and fluorescence changes in the recognition of Cd2+ in tetrahydrofuran (THF). When the fluorescein spirolactam ring-opened form was triggered with Cd2+, an obvious red shift from 459 nm to 560 nm (101 nm) was observed in complex 1O′, and the emission intensity was enhanced by 8 fold with a concomitant fluorescence color change from dark to bright yellow. Significantly fluorescent quenching was observed in ring-closed isomer 1C′ due to the FRET (fluorescence resonance energy transfer) processes between fluorescein moiety and the ring-closed diarylethene moiety. The interference from other effective metal ions, particularly Zn2+, had not been observed. Finally, a molecular logic circuit was constructed with both light and chemical stimuli as inputs and fluorescence intensity at 560 nm as output.