Dual sensitive and selective sensor for Pb2+ and Al3+ with distinctive fluorescence response

A Rhodamine B based dual-response sensor was developed for the independent sensitive and selective fluorescence sensing of Pb 2+ and Al 3+ . Initially, TQ1 exhibited one major fluorescence emission peak centered at 461   nm in ethanol/HEPES solution (1/5, pH 7.4), where HEPES was 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid. After the addition of Pb 2+ , an obvious red shift of 55   nm in fluorescence emission can be clearly observed, accompanied by a fluorescence color conversion, from bluish violet to greenish yellow under 365 UV light. As for Al 3+ , the fluorescence emission of TQ1 experienced a much more remarkable red shift of 124   nm, and its fluorescence color also changed to red. Furthermore, the fluorescence sensing process of Pb 2+ and Al 3+ were completely independent and free from interference of each other via changing the buffer concentration. Detection limit of the probe TQ1 towards Pb 2+ and Al 3+ were 8.3590   ×   10 −7   M (linear range 1.6–10.0   μM) and 1.0568   ×   10 −8   M (linear range 1.0–10.0   μM) respectively. The complexation properties of TQ1 toward Pb 2+ and Al 3+ were studied in detail.