Study On The Synthesis And Fluorescence Properties Of Coumarin Derviatives

In this thesis, we have designed and synthesized some different courmain derivatives. The fluorescence selectivity of the ligands for metal ions has been carefully studied, respectively. The four main parts includes:In the first section, we briefly describe the mechanism of fluorescence and the composition of fluorescent sensors. We introduce the common mechanisms of fluorescent sensors and the progress of coumarn-based sensors in detail.In the second section, we designed a coumarin-based Shiff base (H2L1) as a highly sensitive fluorescent sensor for Al3+in mixed methanol-water solution. As a control study, H2L2was designed to study the function of hydroxyl in the aminophenol. From the study, we can conclude that the hydroxyl in the aminophenol play a vital role in the selective recognition of Al3+. When coordinated with Al3+, the fluorescence of H2L1was significantly increased due to the inhibition of the C=N isomerization process and photoinduced electron transfer process.In the third section, we designed a coumarin-based hydrazine (HL3), which showed strong fluorescence. This molecular was composed of a conjugated couple of electron-donating/electron-withdrawing groups, which showed intense fluorescence due to the internal molecular charge transfer. Cu2+can quench the fluorescence of the ligand completely, while other metal ions can’t.In the fourth section, we synthesized coumarin-based benzimidazole derivate. This ligand gives out strong blue fluorescence under the excitation of ultraviolet light. When binding with Cu2+, its fluorescence was completely quenched in mixed methanol-water (Tris-HCl, pH=7.2,20mM). This probe shows good selective quench effect for Cu2+against other metal ions. Besides, this ligand also presents good two-photon fluorescence, which is friendly to the environment and animals.