Synthesis and characterization of bispentafluorophenyl carbohydrazone/thiocarbohydrazone: selective recognition of F− ions

Herein, we report the synthesis and characterization of bispentafluorophenylcarbohydrazone 1, corresponding thiocarbohydrazone 2 and its potassium salt 3. Compounds 1 and 2 show efficient intermolecular interactions with fluoride anions. However, compound 2 among various anions, binds F− selectively with a large binding constant (3.09 × 106). This interaction is visible to naked eye. Theoretical calculations (DFT and TD DFT) also support these experimental results.