Synthesis Of Naphthalimid-based Colorimetric Probes Of CN~-/F~- And Investigation Of Spectral Properties

Among these biological function anions, fluoride in dental care and treatment of osteoporosis serves as a particularly important role. Fluoride intake is regarded a double-edged sword, appropriate fluoride intake can prevent dental cavities and reduce the prevalence of osteofluorosis, and excessive fluoride intake may lead to human teeth and skeletal fluorosis, kidney and stomach disorders, urolithiasis, which may even cause death. As the smallest and the most negatively charged atoms, fluorine has unique chemical properties, can form the strongest hydrogen bond with hydrogen-bond donors. It is very necessary to design new molecular colorimetric probe and fluorescent probe to detect fluoride and cyanide. These fluorescence probes become attractive, due to their specific output signals and optical response, low-cost. And in some cases, they can detecte the target by the naked eye4-amino-1, 8-naphthalimide-based derivatives have good rigidity and coplanar, simple structure, easy modification on the molecular structure, high luminescence efficiency, large stokes shift for widely utilization in industrial fluorescent dye, photovoltaic materials, laser materials, fluorescent labeling and fluorescent probe.In the first part of our research, we synthesized five naphthalimide derivatives L1, L2, L3, L4 and L5 with different aromatic amines in 4 positon on the 1,8-naphthalimide scaffold, and the molecular structures were characterized via 1H NMR 13 C NMR and HRMS. Among these derivatives, L5 showed excellent selectivity and sensitivity for F- and CN- anions. Probe L5 with cyanide taken place nucleophilic addition reaction, the color was changed from yellow to colorless which led to naked eye detection.In the second part of our research, based on the first part, we synthesized a family of naphthalimide derivatives with different aromatic amines, and some very interesting properties was obtained. We found the naphthalimide derivatives’ fluorescence enhanced with electron-attracting groups added, they had higher sensitivity toward to F-. In addition, the naphthalimide derivatives’ fluorescence weakened with electron-donating groups added and have lower sensitivity toward to F-. We also investigated the influence of the ortho, meta, and para substituents in aromatic amines on the sensitivity of fluoride.