Pyrazoline Fluorescent Compounds Synthesis And Characterization

By now, photoluminescence is a very important and widespread phenomenon, the research and application of inorganic luminescence has a long history, but the inorganic luminescent materials have some formidable shortcomings. Organic luminescent materials may satisfy different uses, they were gradually concerned by people in the field of luminescence. There are a lot of fluorescent compounds, the organic fluorescent compounds take up large proportion. They are generally applied to the organic fluorescent pigments, dyes, coatings, plastics, optical whitening agent, fluorescent source and other fields. With updating and development of synthesis technology, photoluminescence materials are continually used in fields of electroluminescence.According to Schellhammer theory of the relation between chemical structure and fluorescent property, some new carbazolyl-pyrazoline compounds were designed and synthesized. They contain the benzothiazolyl in the 1-pyrazoline, the N-ethylcarbazolyl in the 3-pyrazoline and the derivatives of phenyl in the 5-pyrazoline. These compounds possess fluorescent quality, when the auxochromic group was introduced, the fluorescence is enhanced. The products were characterized by IR spectra, fluorescence emission spectra, MS,1HNMR and elemental analysis. Anilines and aryl ketones and carbazoly were used to synthesize pyrazoline compounds, a novelα,β-unsaturated ketone which contains carbazol was synthesized by solvent-free method, the hydrazine andα,β-unsaturated ketones were used to synthesize products under the alkaline condiction. At the same time, the research and analysis of photoluminescence properties for these compounds had been done. In this paper, eight pyrazoline fluorescent derivatives were synthesized containing benzothiazole and N-ethylcarbazoly. It was shown from the experiments that the maximal absorption wavelength were about 350nm, the fluorescence emission wavelengths were about 430-450nm, these compounds had good fluorescence. The fluorescence maximal emission wavelength and the fluorescence intensity are greatly affected by the substituents on the benzothiazole, shorter fluorescence emission wavelength and higher relative fluorescence intensity are ascribed to the electron-withdrawing group. Moreover, it does not mean that the stronger fluorescence intensity, the higher fluorescence quantum yield.