A highly sensitive, single selective, real-time and "turn-on'' fluorescent sensor for Al3+ detection in aqueous media

A "turn-on'' fluorescent sensor, sodium 4,4',4 ''-(1H-pyrrole-1,2,5-triyl)tri-benzoate (Py(PhCOO-Na)(3)), has been prepared for the detection of Al3+ in aqueous solution. The detection mechanism, as well the mechanism specific to Al3+, was studied by fluorescence spectroscopy, UV-vis spectroscopy and dynamic light scattering (DLS) measurement. Py(PhCOONa)(3) exhibited an aggregation-induced emission (AIE) characteristic and was found to show a specific affinity to Al3+, as indicated by the enhanced and bathochromically shifted emission of the AIE fluorogen. Upon binding Al3+, a significant fluorescence enhancement with a turn-on ratio of over 10-fold was triggered by the AIE process. Moreover, this sensor is highly selective for Al3+ over other metal ions with a detection limit of 5 mu M and a quantitative detection range of 5-120 mu M, and is able to be used in the determination of Al3+ in drinking water. The time-response investigation indicates that the emission intensity of (Py(PhCOO-)(3)) can be quickly boosted to reach the maximum intensity in less than 10 s upon titration of Al3+.