Four N-(2,4-dinitrophenyl)-N -(substituted-phenyl)hydrazones (substituent R＝H, o-OCH₃, o-Cl and o-OH) were synthesized as absorption spectral chemosensors for receptors. The binding properties of these receptors with anions such as F^－ and AcO^－ in CH₃CN were investigated by UV-visible absorption spectroscopy. Results showed that a distinct color change occurred from yellow to light yellow upon addition of F^－ and AcO^－. Substituent was found to exert influence on the spectral response sensitivity and selectivity, with receptor 2 bearing an o-OCH₃ substituent showing the highest selectivity and good sensitivity for F^－. Job plots indicated a 1∶1 anion binding stoichiometry of the receptors, for which a hydrogen bonding interaction was identified from the ¹H NMR titrations and the effect of competitive solvent MeOH on anion binding. As a distinct solution color change occurs it is possible to detect anions such as fluoride by naked eyes.

Key words: N-(2,4-dinitrophenyl)-N -phenylhydrazone, anion sensing, hydrogen bonding