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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 19, Number 9
BKCSDE 19(9)
September 20, 1998 

Unusual Fluorescence Spectroscopic Properties of 9-Anthrylethylene Derivatives : Photoisomerization
Jungkwon Choi, Mahipal A. Reddy, Minjoong Yoon
The fluorescence spectroscopic properties of both trans and cis forms of 9-anthryiethylene derivatives such as 9-AnthCH=CHCO2CH3 [Ⅰ] and 9-AnthCH=CHCN [Ⅱ] as well as 9-AnthCH=CHCH2O2CCH3 [Ⅲ] and 9-AnthCH=CHCH2OH [Ⅳ] have been measured in various solvents. In nonpolar solvent, the trans-I and trans-Ⅱ show dual emission spectral bands at 340 nm and 460 nm when exciting with 270 nm while the other trans derivatives show single emission band at 430 or 460 nm. The dual emissions exhibit different excitation spectra, indicating that two emissive states are different from each other. It is interesting to note that the 340 nm emission of both trans-Ⅰ and trans-Ⅱ is enhanced at the expense of the drastic quenching of the 460 nm emission as the solvent polarity increases. The dual emissions are also observed for both cis-Ⅰ and cis-Ⅱ. The solvent dependence of the fluorescence decay times and quantum yields can be correlated with the solvent and excitation wavelength dependences of the trans→cis photoisomerization quantum yields. These results indicate that the 340 nm emission is originated from the S2 state of the cis-form, and the S1 state is the only singlet excited state presenting a large CT (charge transfer) character to facilitate the photoisomerization.
973 - 980
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