Synthesis And Spectral Properties Of Meso-heptamethine Cyanine Dyes

Heptamethine cyanine dye is a near-infrared dye. Recently, many research works were focused on its application of fluorescent probes and pH sensors, since they can avoid effectively self-absorbence in vivo and autofluorescent background. Modifying its structure will improve the photostability and spectral properties of dyes.In this thesis, indole intermediate was synthesized through the Fischer method with phenylhydrzaine as raw material. Three kinds of heptamethine cyanine dyes on cores of indole solt had been also designed and synthesized with high yield. They are comfirmed through H-NMR and single crystal.Novel heptamethine was synthesized, inducing nitrogen and sulphur atoms into the meso-methines. The spectral properties change remarkably over 100nm of hypsochromic shifts, bigger than common polymetnine dyes.The UV-vis absorption and fluorescent spectra of the novel cyanine dyes with nitrogen atoms vary remarkably with various pH values. In various pH, the changes of structures and electron cloud in cyanine dyes lead to the shift of absorption and fluorescent.For investgating the effect of photostability after inducing nitrogen and surphul atoms, photoreaction experiment was carried out with 1000W I-W lamp. Through the trace of changes of absorption maximam, we calculated the speed of photodegradation. Introducting nitrogen and surphul atoms into heptamethine, the stability of cyanine dyes will decrease. After inducing surphul atoms, the speed of photodegradation of dyes reaches to 3.25×10^-3 molmin^-1, four times of dyes with nitrogen atoms.