Chromium (III) ion-selective “turn-on” and ratiometric probe based on the asparagine bearing dansyl group in aqueous solutions

A new fluorescence probe, dansyl-l-asparagine (Dasn) was synthesized. The probe showed a specific selectivity for Cr3+ over other common metal ions with the fluorescence “turn-on” and the UV–vis absorption ratiometric dual-responses, and it could detect Cr3+ at trace levels (5.2 ppb) in aqueous solutions. The binding model of Dasn-Cr3+ were explored successfully by using UV–vis, NMR and ESI-MS spectra. The results indicated that the dual-responses of Dasn to Cr3+ should attribute to the protonation of the dimethylamino group and deprotonation of sulfonamide group by the coordination of Cr3+ for Dasn.