Two 5,5′-methylenebis(salicylaldehyde)-based Schiff base fluorescent sensors for selective sensing of Al3+ in DMSO/H2O solution

Abstract Two 5,5′-methylenebis(salicylaldehyde)-based Schiff base fluorescent sensors, 1 and 2 , were synthesized. Sensors 1 and 2 both showed selective fluorescent sensing for Al 3+ with low detection limits of 1.49 × 10 −8 and 1.51 × 10 −8  M, respectively, in DMSO/H 2 O (19:1, v/v) solution at the pH value of 5.2. The 1:1 stoichiometries of the Al complexes were determined by Job plots and further verified with LC–MS data and 1 H NMR studies. The sensing mechanisms of sensors 1 and 2 to Al 3+ were proposed. The fluorescence color changes could be easily detected by the naked eye under a UV lamp.