Synthesis and characterization of a novel, ditopic, reversible and highly selective, “Turn-On” fluorescent chemosensor for Al3+ ion

Abstract

We herein report a structurally characterized Schiff base ligand, L, formed by the condensation of 1,1-bis-[2-hydroxy-3-acetyl-5-methylphenyl]methane with 2-picolyl amine. It utilizes the three signalling mechanisms, ESIPT, chelation enhanced fluorescence (CHEF) and CN isomerization, to serve as a “Turn-On” fluorescence chemosensor for Al³⁺. L has high selectivity for Al³⁺ in MeOH. The reversible nature of this chemosensor makes it cost effective. It joins the rare family of ditopic fluorescent chemosensors. When this Schiff base receptor was treated with Al³⁺ salt in MeOH, the fluorescence intensity abruptly increased. Other metal ions did not show such a significant effect on the fluorescence. The detection limit for this chemosensor was found to be 0.7 μM.