Effect of Ground-State Twisting on the trans -> cis Photoisomerization and TICT State Formation of Aminostilbenes

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/28286

Title:	Effect of Ground-State Twisting on the trans -> cis Photoisomerization and TICT State Formation of Aminostilbenes
Authors:	Yang,JS;Lin,CK;Lahoti,AM;Tseng,CK;Liu,YH;Lee,GH;Peng,SM
Contributors:	中央大學
Keywords:	INTRAMOLECULAR CHARGE-TRANSFER;DUAL EXCITED-STATES;MODEL COMPOUNDS;4-DIMETHYLAMINO 4-CYANOSTILBENE;RELAXATION PATHWAYS;INFRARED-ABSORPTION;KERR ELLIPSOMETRY;AB-INITIO;FLUORESCENCE;STILBENES
Date:	2009
Issue Date:	2010-06-29 19:45:30 (UTC+8)
Publisher:	化學研究所
Abstract:	The synthesis, X-ray crystal structures, and photochemical behavior of a series of methyl- and ethylene-bridge-substituted trans-4-(N-(4-cyanophenyl)amino)stilbenes (3-8) are reported and compared to those of the parent compound 1CN. Aminostilbene 1CN displays dual fluorescence in polar solvents due to planar and twisted intramolecular charge-transfer (PICT and TICT) states. Alkyl substitution on the stilbene group of 1CN significantly perturbs its photochemistry, including fluorescence, trans -> cis photoisomerization, and TICT state formation. The alkyl substituent effect can be dissected into electronic and steric influences, and both are position dependent, which is vinyl alpha-carbon > vinyl beta-carbon > phenyl o-carbon. The main outcome of the alkyl substituent effect is to lower the barrier for the singlet-state photoisomerization. As a result, the quantum yield for photoisomerization is increased, and that for fluorescence is reduced. The corresponding quantum yield for TICT state formation in polar solvents is reduced only when significant ground-state twisting (a steric influence) is present. The alkyl substitution exerts little or no effect on the rate of intersystem crossing.
Relation:	JOURNAL OF PHYSICAL CHEMISTRY A
Appears in Collections:	[Graduate Institute of Chemistry] journal & Dissertation

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