A turn-on luminescent europium probe for cyanide detection in water

Abstract

A luminescent europium probe that responds to cyanide directly in water with a large nine-fold turn-on of the Eu^III centered time-gated luminescence is presented. Unlike other CN⁻ probes reported, the mechanism of action of Eu^III-Lys-HOPO does not rely on reaction of CN⁻ with the probe, but on direct coordination of CN⁻ to the Eu^III ion concomitant with displacement of three inner-sphere water molecules. This unusual coordination of CN⁻ with a lanthanide ion in aqueous solution was confirmed by luminescence lifetime measurements.