A new fluorescent 1,8-naphthalimide based chemosensor for detection of dinitrobenzene

The development of chemosensors for the detection of specific ions in solution is a current topic of research, which elegantly combines preparative organic chemistry and spectroscopic studies, with the ultimate goal of... [ view full abstract ]

The development of chemosensors for the detection of specific ions in solution is a current topic of research, which elegantly combines preparative organic chemistry and spectroscopic studies, with the ultimate goal of applying such sensors for biological and environmental purposes. Fluorescent probes are frequently used as the detection unit of chemosensors, combined with a recognition unit, nonetheless, some fluorescent probes may act as a single detection/recognition system.

Therefore, a novel highly water-soluble fluorescence sensing 1,8-naphthalimide unit has been designed, synthesized and investigated as a fluorescent probe. The obtained probe exhibited bright green photoluminescence under UV irradiation. The fluorescence properties of this probe toward various ions of aromatic elements have been investigated by UV-Vis and fluorescence spectra in water solution. According to the ion titration experiments, 1,8-naphthalimide unit showed high sensitivity and selectivity for detection of dinitrobenzene over other ions of aromatic nitro compounds. Upon progressive addition of dinitrobenzene, a gradual quenching process in fluorescence intensity of 1,8-naphthalimide based sensor was observed, due to inhibition of the PET process. The fluorescent detection limits of 1,8-naphthalimide was calculated to be 0.15µM and the Stern-Volmer quenching constant was found to be K_sv = 3.32 × 10^-5 M⁻¹. The higher sensitivity of synthesized 1,8-naphthalimide unit towards aromatic ions can be attributed to a combination of fluorescent, steric and electronic factors. These results indicate a greater sensitivity of the fluorescent probe towards dinitrobenzene ions, that the fluorescent  1,8-naphthalimide based chemosensor can be used as a potential probe for dinitrobenzene detection.