Ratiometric fluorescent scaffold giving discrete response towards iodide ion: a combined experimental and DFT study

A novel ratiometric fluorescent receptor (Z)-2-(4-[diethylamino]-2-hydroxybenzylideneamino) pyridine-3-carbaldehyde (3) bearing one phenolic OH and one aldehyde group as recognition sites was synthesized and characterized. The anion recognition behaviour of receptor 3 was evaluated by various spectroscopic (UV-visible, fluorescence and (1) H nuclear magnetic resonance) methods and was validated by computational studies. The receptor showed fast response time, excellent selectivity and reproducibility towards iodide ion detection among the other surveyed anions, with a binding constant of 6.12 × 10(4)  M(-1) and a detection limit of 0.24 μM, thus confirming its potential applicability as a fluorescent sensor for iodide.