Fluorescent sensors based on controllable conformational change for discrimination of Zn2+ over Cd2+

A new coumarin-derived imine IC1 was designed for highly selective sensing of Zn2+ over Cd2+ ions in aqueous solution based on a controllable Cdouble bond; length as m-dashN isomerization mechanism. Methyl as a fine controllable unit was incorporated into IC1 to tune the conformational change of imine and thus significantly improve its selectivity to Zn2+ compared with methyl-free imine IC2. Sensor IC1 was also utilized to image intracellular Zn2+ ions in HepG2 cells with a good performance.