The Design And Synthesis Of Indolium Tricarbocyanine Dyes, Coumarin Derivatives And Investigation Of Their Spectral Properties

Fluorescent molecular probes which can transfer molecular recognition events into fluorescence signals were widely applied recently for their good merits, ie. high sensitivity, good selectivity and real-time in situ detection. Indolium tricarbocyanine dyes have its inherent advantages and widely used as a platform for construction of fluorescent probes because their spectra reach the near-infrared (NIR) region where a biological matrix exhibits the least absorption and autofluorescence background. Coumarins is an another excellent fluorophore dye in molecular design of fluorescent probe with high fluorescence quantum yield, large Stokes shift, and good photostability. Our work is based on the two fluorescent dyes. This disstertation consists of three chapters summarizad as follows:In ChapterⅠ, we have first introduced the design principles and signal response mechanism of fluorescent molecular probes, second we have introduced synthesis methods of the Indolium tricarbocyanine dyes and their application as a fluorescent probe toward metal cations, anios and small bio-molecules. Next we aslo introduced progressed research of fluorescent probe based on coumarin dyes. Finally, we have proposed content of this research.In ChapterⅡ, four meso amine-substituted and phenol-substituted Indolium tricarbocyanines derivatives have been successively synthesized. And the previous reaction conditions have been changed in the reaction process rendering the reaction temperature to be greatly reduced. Upon studying the spectral properties of the four amine-substituted derivatives, we found that the species of substituents and the position of substituents on the benzene ring show great influence on the absorption spectra and fluorescence quantum yield of the dyes. The synthesized four amine-substituted dyes exhibit large Stokes shifts. For example, the Stokes shifts of the compuonds 5a and 5b are greater than 90 nm. However, the absorption and emission spectra become wider, and fluorescence quantum yields is very low (less than 0.004). These may be the co-effect of intramolecular charge transfer (ICT) and the photoinduced electron transfer (PET) in the two derivatives. Through investigating the spectral properties of phenol-substituted derivatives, the phenol-substituted derivatives have large molar extinction coefficients, small stokes shifts, but the fluorescence quantum yields are generally high which is due to the less effect of PET. The fluorescence quantum yields of the tricarbocyanine dyes will be decreased providing the electron donor ability of substituents on the benzene ring increasing, which is due to the photoinduced electron transfer (PET) mechanism.In ChapterⅢ, we designed and synthesized a new coumarin dye-the fluorescent Chemodosimeter 8 for benzenethiols based on the thiolysis of dinitrophenyl ethers. Contrast to previous reported thiols probes which can not effectively discriminate benzenethiols from aliphatic thiols, or not successfully applied practical, probe 8 is a new highly sensitive and effective fluorescent probe for benzenethiols with a detection limit of 1.8×10-9 M. Our new probe is effective for sensing benzenethiols in water, soil, and the living cells. Furthermore, benzenethiol vapor could also be selectively detected by the test papers of probe 8. The reaction product of probe 8 with benzenethiol was isolated by column chromatography, and its structure was subjected to the MS and 1H NMR analysis.