A pyridine-dicarbohydrazide-based chemosensor for detecting Al³⁺ by fluorescence turn-on

A pyridine-dicarbohydrazide-based chemosensor TMC (N², N⁶-bis((E)-5-chloro-2-hydroxybenzylidene)pyridine-2,6-dicarbohydrazide) showed a marked fluorescence response with Al³⁺. With analysis of Job plot and electrospray ionization (ESI)-mass spectrometry, the association of TMC to Al³⁺ was determined to be a 1:1 ratio. Detection limit of TMC for Al³⁺ was 1.56 μM. Especially, TMC could distinctly distinguish Al³⁺ from Ga³⁺ and In³⁺. TMC could suitably analyze Al³⁺ in a real environment with great recovery and relative standard deviation (RSD). In addition, TMC-coated test kits can be practically used for recognition of Al³⁺. Binding process of TMC to Al³⁺ was illustrated with density functional theory (DFT) calculations, NMR titration, ESI-mass, and UV–vis experiments.