A selective fluorescent probe based on bis-Schiff base for "turn-on" detection of Al3+ and cysteine by different mechanisms. Issue 30 (8th March 2016) - Li, Yang
Abstract : A novel fluorescent sensorL based on phenolphthalein derivative bis-Schiff base for "turn-on" detection of Al 3+ and cysteine on different mechanisms. Abstract : In the paper, a novel fluorescent sensorL based on phenolphthalein derivative bis-Schiff base was synthesized and characterized. ChemosensorL was found to be an excellent specific receptor for Al 3+ via significant fluorescent enhancement resulting from the inhibition of an internal charge transfer (ICT) process and an efficient chelation-enhanced fluorescence (CHEF) effect. A good linear relationship was obtained in the Al 3+ concentration from 0 to 50 μM with the detection limit reaching below 15 nM. Moreover, the addition of 2 equiv. of Cu 2+ can almost completely quench the emission intensity ofL due to a ligand–metal charge transfer (LMCT) process. The resultingL –Cu(ii ) complex showed a satisfactory sensing ability toward cysteine (Cys) through naked-eye and recovered fluorescence intensity with the detection limit of 0.36 nM. The fluorescence recovering process was caused by the stronger coordination ability of Cys with Cu 2+ than withL and therefore freeL was released from theL –Cu(ii ) complex. Furthermore, the sensor was used to detect Cys in practical samples with a high accuracy.