Synthesis of Novel Thiazole Based Carbaldehyde as Potential Sensor for Fluoride Anion and their Spectroscopic Properties.

A novel thiazole based carbaldehyde bearing benzimidazole fluorophore as the receptor unit for F - anion was prepared by multi steps synthesis. Density functional theory was used to understand the structural and electronic properties the receptor. The anion sensing activities of receptor 4 were studied for various anions in acetonitrile solvent. The receptor showed fluorescence enhancement in the presence of fluoride anion due to intramolecular charge transfer (ICT) mechanism. No significant changes were observed upon addition of less basic anions such as OAc-, Cl-, Br-, I-, HSO4-. After the interaction of fluoride anion with the receptor 4 leads to an 88 nm red shift in emission maxima. [TBA]OH and 1H NMR titration experiments indicated that deprotonation of N-H in the benzimidazole due to interaction with fluoride anions.