Benzimidazole-based receptor for Zn2+ recognition in a biological system: a chemosensor operated by retarding the excited state proton transfer

A new benzimidazole-based receptor was developed with potential functional groups for excited state proton transfer (ESPT) through keto–enol tautomerism. The enol form of the receptor selectively recognizes Zn2+, allowing it to be used as a ratiometric fluorescence sensor in DMSO/CH3CN (1:9, v/v). The binding event triggers a blue-shifted band through the modulation of charge transfer transitions. The sensor is applicable for recognizing Zn2+ in the cytoplasm of Saccharomyces cerevisiae.