Synthesis And Property Studies Of Pyridiniums Organic Nonlinear Optical Materials

Several nonlinear optical pyridiniums were designed and synthesized tobalance the nonlinearity-transparency trade-off by molecular engineering theoryand crystal engineering theory. The pyridiniums were characterized by IR,1HNMR,13C NMR, MS, UV-Vis and fluorescence spectra. The second-orderpolarizability of the chromophores was determined by a solvatochromic methodbased on two-level model. The chromophores have large second-orderpolarizability and exthibit good transparency. The nonlinearity-transparencytrade-off is due to the two-dimensional structure, the choice of electron acceptors,electron donors and the conjugation length.The main task of this dissertation includes the following research works:designing and synthesizing a series of pyridiniums nonlinear optical organicmaterial, determining the structures of the pyridiniums by test means such aselementary analysis, infrared spectrum and nuclear magnetic resonance,measuring molecular second-order nonlinear polarizabilities by solvatochromismmethod, and discussing the relationship between molecular structures andsecond-order nonlinear polarizabilities (β) of the pyridiniums. Main researchworks are as follows:1. New pyridiniums NLO materials with one-dimensional D-π-A structure aredesigned and synthesized. They are ISPI, ISPT, ISSPI and ISSPT.2. The tosylate ions are replaced with the iodine ions to obtain two series ofpyridiniums NLO materials with different anions.3. Two two-dimentional A-π-D-π-A pyridiniums NLO materials with carbazolyare designed and synthesized. They are3,6-CVPI and1,8-CVPI.4. Synthetic routes to the target pyridiniums NLO materials are designedreasonably. Some synthetic methods are improved appropriately. The improvedreactions have faster speed, higher yield and purer products. In addition, reaction conditions of the improved reactions are optimized.5. The structures of the pyridiniums NLO materials are characterized withmodern test means such as elementary analysis, infrared spectrum,1H-nuclearmagnetic resonance and13C-nuclear magnetic resonance.6. Single crystals of pyridiniums are produced by crystal grown method ofslow solvent evaporation. The crystal structures are determined by X-Ray singlecrystal diffraction.7. The UV-vis absorption spectra and the fluorescence emission spectra of thepyridiniums NLO materials are studied. The second-order polarizabilities of thepyridiniums are determined by solvatochromic method. These pyridiniums NLOmaterials have higher second-order polarizabilities and better transparency, andexhibit excellent nonlinearity-transparency trade-off.