A novel “turn-off” fluorescent sensor for Al3+ detection based on quinolinecarboxamide-coumarin

Quinolinecarboxamides based on coumarin derivatives were efficiently synthesized and the optical properties were investigated. Compound ZXQ substituted by the diethylamino group on 7-position of coumarin exhibited blue fluorescence (λem ≈ 470 nm) with a high fluorescence quantum yield of 0.92 in Toluene and showed “turn-off” fluorescence property for Al3+. Probe ZXQ formed the 2:1 complex with Al3+ and performed fluorescence quenching in MeCN/H2O (95:5), which exhibited good selectivity and sensitivity. In addition, the mechanism of binding and fluorescence quenching was illustrated by titration experiment, Job’ plot and DFT calculations.