Abstract:

Six styryl pyrazine compounds, in which some are streically hindered rotation and some are freely rotated, have been sythesized in this work. The effects of temperature and solvent polarity on the photophysics and luminescence behavior of these compounds were studied in detail. Results indicated that blocking of the double bond twist by a sufficiently rigid bridge increases fluorescence quantum yields dramatically and the single bond connecting the double bond twisted is favorable to the formation of T* state （radiation decay）. One of the resons for distytyl pyrazines having higher fluorescence quantum yields may be due to the less probability of transformation from E* state to P* state.

Key words: Styryl pyrazine, Steric hindrance, Intramolecular rotation, Intramolecular charge transfer