Recognition and sensing properties of nitro-substituted phenyl hydrazone-based fluorescence receptors for anions

Nitro-substituted phenyl hydrazone-based fluorescence receptors containing naphthalene substituent have been designed and synthesized. The recognition and sensing properties for anions were studied by UV-Vis spectrophotometry, fluorescence spectroscopy and 1H NMR. The results show that nitro-substituted phenyl hydrazone-based fluorescence receptors exhibit a high selective colorimetric and fluorescent recognition for F- in the DMSO solution. Especially, receptors bearing two nitro-groups on the phenyl hydrazone moiety, leading to the further increase of the acidity of hydrazone NH proton, have an additional colorimetric and fluorescent response to AcO- in the DMSO solution, and also show a high selective colorimetric and fluorescent sensing for F- in the DMSO-H2O media. The hydrazone-based receptors can act as efficient "off-on" fluorescence probes for anions. The study on the mechanism of the anion recognition and sensing has also been carried out.