Dansyl-8-aminoquinoline as a sensitive pH fluorescent probe with dual-responsive ranges in aqueous solutions

• A new fluorescence probe (DAQ) for pH was synthesized.
• The probe exhibits a specific selectivity for pH in aqueous solution.
• The probe could sensitively respond to pH with dual-responsive ranges.

A sensitive pH fluorescent probe based on dansyl group, dansyl-8-aminoquinoline (DAQ), has been synthesized. The probe showed dual-responsive ranges to pH changes, one range from 2.00 to 7.95 and another one from 7.95 to 10.87 in aqueous solution, as it showed pKa values of 5.73 and 8.56 under acid and basic conditions, respectively. Furthermore, the pH response mechanism of the probe was explored successfully by using NMR spectra. The results indicated that the responses of DAQ to pH changes should attribute to the protonation of the nitrogen atom in the dimethylamino group and deprotonation of sulfonamide group.

A sensitive pH fluorescent probe (dansyl-8-aminoquinoline, DAQ) has been synthesized. The probe could selectively and sensitively respond to pH with dual-responsive ranges from 2.00 to 7.95 and from 7.95 to 10.87 in aqueous solution, as it showed pKa values of 5.73 and 8.56 under acid and basic conditions, respectively.Figure optionsDownload as PowerPoint slide