Synthesis And Properties Of Hexamethinecyanine Dyes Containing Isophorone

Cyanine dyes, as a new class of functional moleculars, have shown extensive applications in optical materials, solar cells, pH sensors and biological fluorescent probes due to their excellent optical properties. With the development of experimental level and research technology, the requirements to cyanine dyes have been continually improved, especially in the biomedical field. Thus, dye molecules who have higher stability, excellent spectral properties and water-soluble become the object that people want to research. Because of this reason, our study group introduces the isophorone nuclear into the methine chain of dyes and synthesizes six hexamethinecyanine dyes containing isophorone nuclear. Furthermore, their structural characterization and spectral properties were also investigated.This dissertation included three aspects which are as follows:1. The general properties of cyanine dyes and their application have been introduced, especially structure features and their research progress of bridge chain methine dyes.2. The six products were prepared from 2-methyl-benzothiazole,2-methyl-β-naphthalene thiazole and indole formaldehyde as initial materials, through condensation reaction. Their structures were characterized through 1H NMR,13C NMR, IR, UV-Vis and HRMS.3. The UV-Vis and fluorescent spectra of the six dyes in various solvents (methanol, ethanol, water, chloroform, acetone, dimethyl sulfoxide) were investigated. The results indicated that the maximum absorption wavelength (λmax) of six dyes D1-D6 ranging between 493.0 nm-607.5 nm, and their molar extinction coefficient is between 2.66×104-8.06×104 L·mol-1cm-1, whose magnitude is 104. Their fluorescence maximum emission wavelength and Stokes shift were in the range of 675-718.8 nm and 107.7-279.2 nm in different solvents, respectively. The results suggested that, with thiazole ring or naphthalene ring in the same side of the dye molecules, the maximum absorption wavelength of D2, D4 and D6 whose indole ring were substituted by a carboxyl group were always longer than D1, D3 and D5 that indole ring were substituted by benzyl. Further, the maximum absorption wavelength of each dye in the three protic solvent (ethanol, methanol, water) and three aprotic solvents (chloroform, acetone, dimethylsulfoxide) present the same pattern which the absorption was hypsochromic-shifted with the solvent dielectric constant increasing. The order of fluorescence quantum yield of each dye in three proton solvent was:Φfree (H2O)<Φfree (MeOH)<Φfree (EtOH), suggesting that fluorescence quantum yield was significantly reduced with the increase of solvent polarity, meanwhile, there was the strongest fluorescence in chloroform with the least polar aprotic of three aprotic solvents. Furthermore, fluorescent spectra of the six dyes showed weak fluorescent of six in water. Cytotoxicity experiments illustrate that six dye molecules had low toxicity and they can be applied in cell experiments.