DC Field | Value | Language |
---|---|---|
dc.contributor.advisor | Shim, Sang-Chul | - |
dc.contributor.advisor | 심상철 | - |
dc.contributor.author | Lee, Cheon-Seok | - |
dc.contributor.author | 이천석 | - |
dc.date.accessioned | 2011-12-13T04:58:02Z | - |
dc.date.available | 2011-12-13T04:58:02Z | - |
dc.date.issued | 1989 | - |
dc.identifier.uri | http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=66570&flag=dissertation | - |
dc.identifier.uri | http://hdl.handle.net/10203/32542 | - |
dc.description | 학위논문(석사) - 한국과학기술원 : 화학과, 1989.2, [ vii, 58 p. ] | - |
dc.description.abstract | Fluorescence quantum yields of 5(E)-styryl-1, 3-dimethyluracils (4``-X-5(E)-SDU``s) are more affected by the solvent viscosity than by its polarity except 5 (E)-(4``-nitrostyryl)-1,3-Dimethyluracil (4``-NO$_2$-5(E)-SDU). The fluorescence maxima shift slightly to the long wavelengh with increasing the solvent polarity indicating that the lowest excited fluorescent states are the 1($\pi,\;\pi^\ast$) states. However, the lowest singlet state of 4``-NO$_2$-5(E)-SDU has (n,$\pi^\ast$) character in non-polar solvents, but with increasing the solvent polarity the lowest singlet state changes from ($\pi,\;\pi^\ast$) to ($\pi,\;\pi^\ast$) state. Relatively weak fluorescence of the substituted 5 (E)-SDU``s implies the significant contribution of the ($\pi,\;\pi^\ast$) state introduced by the heteroatom to the lowest excited singlet state leading to the fast internal conversion or intersystem crossing. Photoisomerization quantum yields of 4``-halogen substitution are similarly influenced by solvent viscosity as the unsubstituted 5(E)-SDU while little affected by solvent polarity. However, photoisomerization quantum yields of 4``-OCH$_3$-and 4``-CH$_3$-5(E)-SDU``s depend on the nature of the solvents, while for 4``-nitro derivative it is strongly affected by solvent polarity. The azulene quenching experiments on the direct and sensitized photoisomerization of the substituted 5(E)-SDU``s indicate that singlet mechanism for the direct photoisomerization of 4``-OCH$_3$-and 4``-CH$_3$-5(E)-SDU``s is operative, and both singlet and triplet mechanism for 4``-halogen substituted 5(E)-SDU``s are operative. However, direct photoisomerization of 4``-NO$_2$-SDU occurs in the triplet manifold. | eng |
dc.language | eng | - |
dc.publisher | 한국과학기술원 | - |
dc.title | Substituent effects on the photoisomerization of 5(E)-styryl-1,3-dimethyluracil | - |
dc.title.alternative | 5(E)-스티릴-1,3-디메틸우라실의 광이성질화 반응에대한 치환기 효과 | - |
dc.type | Thesis(Master) | - |
dc.identifier.CNRN | 66570/325007 | - |
dc.description.department | 한국과학기술원 : 화학과, | - |
dc.identifier.uid | 000871337 | - |
dc.contributor.localauthor | Shim, Sang-Chul | - |
dc.contributor.localauthor | 심상철 | - |
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