A highly selective and sensitive photoswitchable fluorescent probe for Hg2+ based on bisthienylethene–rhodamine 6G dyad and for live cells imaging

• A new photoswitchable bisthienylethene–rhodamine 6G dyad is successfully designed.
• It exhibits an excellent selectivity and a high sensitivity toward Hg2+.
• It is successfully applied to detect the Hg2+ in live A549 lung cancer cells imaging.

A new photochromic diarylethene derivative bearing rhodamine 6G dimmer as a fluorescent molecular probe is designed and synthesized successfully. All the compounds are characterized by nuclear magnetic resonance and mass spectrometry. The bisthienylethene–rhodamine 6G dyad exhibit excellent phtochromism with reversibly color and fluorescence changes alternating irradiation with ultraviolet and visible light. Upon addition of Hg2+, its color changes from colorless to red and its fluorescence is remarkably enhanced. Whereas other ions including K+, Na+, Ca2+, Mg2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Mn2+, Pb2+, Ni2+, Fe3+, Al3+, Cr3+ and so on induce basically no spectral changes, which constitute a highly selective and sensitive photoswitchable fluorescent probe toward Hg2+. Furthermore, by means of laser confocal scanning microscopy experiments, it is demonstrated that this probe can be applied for live cell imaging and monitoring Hg2+ in living lung cancer cells with satisfying results, which shows its value of potential application in environmental and biological systems.

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