A colorimetric and turn-on fluorescent chemosensor for Al(III) based on a chromone Schiff-base

A simple Schiff-base receptor 7-methoxychromone-3-carbaldehyde-(pyridylformyl) hydrazone (MCNH) was prepared. It exhibits an off-on-type mode with high sensitivity in the presence of Al3+. This compound could be used as Al3+ probe in ethanol and it features visible light excitation (433 nm) and emission (503 nm) profiles. Upon binding of Al3+, a significant fluorescence enhancement with a turn-on ratio over 800-fold was triggered. However, other metal ions had no such significant effect on the fluorescence. MCNH can also be used as a colorimetric chemosensor for Al3+, which is easily observed from colorless to yellow-green by the naked-eye. The detection limit of MCNH for Al3+ was as low as 1.9 x 10(-7) M. (C) 2013 Elsevier B.V. All rights reserved.