Synthesis, Spectral Properties Of Quinoline Cyanine Dyes With Double D-π-A Conjugated System As Well As Their Films On Silicon

The class of cyanine dyes with double D-π-A conjugated system possess very attractive photophysical characteristics, such as long-wavelength absorption, high molar absorption coefficients and good stability and so on. Besides that they have good stability and high affinity to cellmembranes and biomolecules. However at present the study of this kind of dyes has not been done thoroughly, especially their research in the material field are rare. In this dissertation, two kinds of new quinoline cyanine dyes with double D-π-A conjugated system were designed and synthesized and their spectral properties in six different solvents were investigated. Moreover, the two dyes were attached on the surface of monocrystalline silicon by means of self-assembling to explore the potential applications in photoelectric materials.This dissertation included three aspects which were as follows:1. The literature about the research of cyanine dyes with double D-π-A conjugated system was summarized. Meanwhile, the methods and applications progress of silicon surface modified by organic molecules were also reviewed.2. Two new quinoline cyanine dyes with double D-π-A conjugated system were designed and synthesized. Their structures were identified by UV-Vis, H NMR, IR and HRMS and optimized by means of quantum chemical calculations. The vibrational band had been done using a combination of experimental infrared spectra compared with results obtained from DFT calculations. The UV-Vis and fluorescent spectra of the two dyes in six different solvents were also investigated. The results showed that λmax of them in the protic solvents undergoed hypsochromic shifts as the solvent polarity increased and they exhibited strong fluorescence in chloroform.3. The two quinoline cyanine dyes are attached on the surface of monocrystalline silicon via Si-O bond and form molecular film. The molecular film were characterized by XPS and AFM. The investigation of surface photovoltage response shows that the surface modification of monocrystalline silicon with double D-π-A quinoline cyanine dyes can improve the optical properties of semiconductor silicon materials in near infrared region.