A facile fluorescent probe based on coumarin-derived Schiff base for Al3+ in aqueous media

A facile coumarin-based Schiff base sensor, 7-hydroxy-8-((2-hydroxy-phenylimino)methyl)-coumarin (H2L), has been designed and synthesized for selective detection of Al3+ in methanol-water (1:1, v/v). A fluorescence enhancement of 12-fold at 528 nm can be realized upon addition of 5.0 equiv. Al3+ with excitation at 421 nm. The mechanism of C=N isomerization, coupled with photoinduced energy transfer, is proposed to explain the observed spectral response. Most importantly, this Al3+ sensor has good water-solubility and can be excited with light in the visible range. (C) 2013 Elsevier B.V. All rights reserved.