A Novel Dual Channel Fluorescent Probe for Ca2+ and Zn2+ Based on a Coumarin Schiff Base

A novel coumarin Schiff base fluorescent probe ethyl 7-hydroxycoumarin-3-carboxylate-8-formaldehyde benzoyl hydrazone (EBH) has been designed and synthesized which shows solvent dependent dual sensing, viz., recognition of Ca2+ in DMF-H2O (9∶1, V/V) solution based on C = N isomerization, photoinduced electron transfer (PET) inhibition and chelation-enhanced fluorescence (CHEF) mechanism as well as detection of Zn2+ in H2O-CH3OH (9∶1, V/V) solution by excited-state intramolecular proton transfer (ESIPT) and CHEF processes. The structure of the probe EBH has been confirmed by single-crystal X-ray diffraction analysis. Meanwhile, the probe was also used to image intracellular Zn2+ ions in MCF-7 cells with a good performance.