Synthesis And Characterization Of Heterocyclic Organic Nonlinear Optical Materials And Study Of Tautomerism

Much attention has been paid to nonlinear optical materials due to their potential applications prospects in the fields of information transmission and conversion and the optical element. Organic materials have been broadly researched because of their large nonlinear optical coefficient, fast response speed, flexible design means and low cost. But to achieve the effect of practical application, the comprehensive performance of organic nonlinear optical materials must be optimized to explore organic nonlinear optical materials with excellent comprehensive performance.The basic theories and applications of nonlinear optics, design basis of organic nonlinear optical compound and test methods of optical performance, are briefly described in this paper and it focuses on the experiences and methods of resolving the "non-linear-translucency contradictions" existing in organic nonlinear optical materials at home and abroad currently.A kind of new organic nonlinear optical compound with D-Ï€-A structure, 1,8-dihydroxy-4(5-nitro-2-thiazolyazo)-9,10-dihydroanthracene is synthesized. At the same time, two kinds of new compounds are obtained and characterized by 1H-NMR, 13C-NMR and FT-IR(KBr), UV-vis, fluorescence spectroscopy and thermal gravimetric analysis to investigate the structure of the compound synthesized.The non-linear second-order susceptibility of organic nonlinear optical molecules is determined by a solvatochromic method. The effects of solvent variety and concentrationon on azo-type-quinone hydrazone-type tautomeric equilibrium of nonlinear optical molecules synthesized, are analysed using UV-vis and NMR. In addition, an influence of presence of a trace of acetic acid on azo-type-quinone hydrazone-type tautomeric equilibrium is also studied.The solvatochromic method show that the compound synthesized have good transparency with maximum absorption wavelength for 455⁴69nm (ethanol azo-type), and have large non-linear second-order polarization rate for 109×10^-30esu at the wavelength of 1064nm. The organic nonlinear optical molecules synthesized with high thermal stability, thermal decomposition temperature reaches 278℃, which is proved by TGA. It is indicated that organic nonlinear optical molecules synthesized haveazo-type-quinone hydrazone-type tautomeric equilibrium in the solvent by UV-vis absorption spectroscopy, 1H-NMR spectra and 13C-NMR spectra. The compound with different solvent concentrationon all exist as azo type in ethyl acetate; The content of azo-type increases with the increase of solution concentration and the content of hydrazone-type increase with the decrease of solution concentration in ethanol and acetone. The compound with different solvent concentrationon all exist as hydrazone-type in N,N-dimethylformamide(DMF). The presence of a trace of acetic acid is beneficial to the formation of azo-type, while inhibiting the formation of hydrazone-type. The chemical shift of carbon and hydrogen in the quinone ring of hydrazone-type shift to a low field relativing to the azo-type, while that of carbon and hydrogen in the thiazole ring shift to a high field relativing to the azo-type.