Luminescence Lifetime-Based Sensor for Cyanide and Related Anions

A new Ru(II) complex is described which serves as a luminescence lifetime-based sensor for fluoride and cyanide anions (K F = 640 000 mol-1, K CN = 430 000 mol-1). This chromophore displays observable changes in its UV−vis and steady-state luminescence spectra upon cyanide binding. Prior to cyanide addition, this complex exhibits a single-exponential lifetime (τ = 377 ± 20 ns). With increasing cyanide concentrations, the intensity decays are composed of two exponentials: long τ (320−370 ns) and short τ (13−17 ns). The average lifetimes shorten as a function of cyanide concentration since the fractional intensity shifts from an initial dominant long lifetime component to the short lifetime component. This work represents the first example of a direct method for the luminescence lifetime-based sensing of anions.