Development of fluorescent chemosensors for Al3+ is one of the important research areas as the presence of the cation is responsible for many health issues. The study presents the development and analysis of a novel Al3+ detecting compound, 4-(2-(4-hydroxy-3-((quinolin-3-ylimino)methyl)phenyl)propan-2-yl)-2-((quinolin-3-ylimino)methyl)phenol (abbreviated as H2P). The probe was obtained by a simple condensation of bisphenol A dialdehyde and 3-amino quinoline (1:2 ratio) in methanol under mild conditions. A distinct color change was observed in the bare eye under UV light in the presence of Al3+, whereas other metal ions remained unresponsive. The fluorescence probe demonstrates a remarkable enhancement in fluorescence intensity, specifically a 29-fold increase at 466 nm, when exposed to Al3+. This phenomenon has been attributed to two mechanisms: the chelation enhanced fluorescence (CHEF) effect and the inhibition of C=N isomerization. The probe exhibits high sensitivity toward Al3+, with a detection limit of 1.48 × 10-7 M. Furthermore, it forms a complex with the cation in a 1:2 ratio (ligand to metal), characterized by an association constant of 3.30 × 104 M-1. The application of H2P demonstrated efficacy in detecting Al3+ within water samples.
Bari et al. (Sun,) studied this question.