First, 7-hydroxy-4-methylcoumarin (5.00 g, 0.0284 mol) and hexamine (10.0 g, 0.071 mol) in acetic acid (37 mL) were stirred for 5.5 h at 95 C. Then, hydrochloric acid (75 mL, HCl: H2O = 84:100, v/v) was added and further
College of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 211189, P. R. ChinaA novel chemosensor L based on coumarin Schiff-base was synthesized and investigated. Sensor L showed remarkable selectivity for Al 3+ in Tris-HCl aqueous buffer solution (pH 7.2), and the selectivity was not affected by the presence of a large excess of other competitive ions. The sensor responded rapidly to Al 3+ in aqueous solutions with a 2:1 stoichiometry. Meanwhile, it indicated significant improvement of quantum efficiency and ideal fluorescent lifetime.