Isatin-1,8-Naphthalimide Hydrazones: A Study of Their Sensor and ON/OFF Functionality

Five novel hydrazones derived from substituted isatins were synthesized as potential anion sensors. Using UV-VIS, FTIR, NMR and fluorescence spectroscopy, these compounds’ tautomeric equilibrium and Z-E photoisomerization were studied in DMF and CHCl3, depending on the hydrazone concentrations, the presence of basic anions and light stimulation. Anion recognition aspects (PF6−, HSO4−, Br−, Cl−, NO3−, F− and CH3COO−) and these receptors’ detection limits were also studied. We also tested the light-stimulated ON-OFF functionality of these compounds in the presence or absence of these anions.