Design, Synthesis And Application Of Fluorescent Probes Based On1,8-naphthalimide And Triphenylamine

In this thesis, we have designed and synthesized fluorescent probes for Pd2+, sulfite and bisulfite based on1,8-naphthalimide. And we employed Triphenylamine derivatives for pH sensing.Palladium is widely used in materials and catalysts. This heavy metal ion is harmful to environment and human. It can bind biomacromolecules and destroy their functions. We designed and synthesized compound1and2for Pd2+detection. Both of them contain a propargyoxy structure, which can react with Pd2+ion.4-amino-l,8-naphthalimide (4-AN) is green fluorescent. In the structures of1and2, the amino group of4-position on the fluorophore is connected with an electron-withdrawing moiety so that the electron-donating ability of the amine is weakened, which results in blue fluorescence of the probes. The detection mechanism is that the intramolecular rearrangement of1and2resulting from Pd2+catalyzed hydrolysis generates the fluorophore4-AN and shows absorbance, fluorescence changes. We have demonstrated this mechanism through HPLC and LC-MS. We have found that probe2has high fluorescence increasment, while probe1has a faster reaction rate. Both of them have good selectivity and can be applicated for detection of practical samples.Sulfite and bisulfite are often used as additive. Sulfite is the metabolite of sulfur containing substances in human. It can regulate multiple physiological functions and will cause illness and adverse reactions when the concentration is high. We designed and synthesized compound3,4and5with different substituted heterocyclic moieties. We screened and found compound3that can effectively detect sulfite and bisulfite. Molecular modeling and NMR analysis indicate that sulfites ions bind with imine moieties of naphthalimide and pyrrole ring through hydrogen bonding.3have a planar structure and pyrrole ring quenches the fluorescence via PET effect (photoinduced electron transfer). Upon binding with the anions, the planar structure is twisted so that PET effect is blocked, leading to fluorescence enhancement.3have good sensitivity and selectivity. The detection limit is0.56?M. We synthesized a SO2donor and monitored the real-time release of SO2through detection of sulfite and bisulfite generated by SO2in water. Given the importance of sulfite ion in physiological functions, we carried out detection of sulfite in cells.A suitable pH environment is important for normal cell functions. Abnormal pH can cause physiological function disorders. Here we employed Triphenylamine derivatives6,7and8for detection of pH changes. All of them show fluorescence enhancement with increasing pH values ranging from2to7and display color change that can be observed by naked eyes. When pH have a cycle changes in2and7, compound6,7and8also display cycle changement in color and fuorescence intensity. Through molecular modeling, it's found that the molecule plane of pyridine group is switched to be perpendicular to the triphenylamine plane after binding with protons, which destroys the original D-?-A structure and quenches the fluorescence. After deprotonation, fluorescence is switched on. Compound6,7and8can rapidly respond to pH changes and can be utilized in detection of pH changes in cell environment.