Terphenyl based fluorescent chemosensor for Cu2+ and F− ions employing excited state intramolecular proton transfer

A new terphenyl based bifunctional fluorescent chemosensor 3a has been synthesized, which demonstrates selective optical recognition of Cu2+ and F− ions in two contrasting modes. The compound shows highly selective ‘On–Off’ switchable behavior toward Cu2+ ions and ‘On–Off–On’ behavior toward F− ions among various cations and anions tested. The detection limits of chemosensor for Cu2+ and F− ions are found to be 100 nM and 10 nM, respectively.