Effects of solvents and substituents controlling the adiabatic or diabatic modes of the cis → trans isomerization of styrylpyrenes in the excited singlet state
The effects of polar solvents and polar substituents on the potential energy surfaces of the cis → transisomerization of 1-styrylpyrenes in the excited singlet state are investigated by fluorescence spectroscopy. In less polar solvents, cis-1-styrylpyrene undergoes an adiabatic isomerization from the cis excited singlet state (1c∗) to the trans one (1t∗), overcoming an energy barrier around the perpendicular
通过荧光光谱研究了极性溶剂和极性取代基对激发单线态1-苯乙烯基苯乙烯的顺式→反式异构化的势能表面的影响。在极性较小的溶剂中,顺式-1-苯乙烯基苯乙烯经历了从顺式激发单重态(1 c ∗)到反式一(1 t ∗)的绝热异构化过程,克服了垂直构象周围的能垒(1 p ∗)。溶剂极性的增加和/或在苯环上引入极性p-取代基可改变反应进程,并从1 p ∗失活 导致非绝热异构化。
Effect of Substituents on the Equilibrium between Trans and Perpendicular Conformers in the Triplet Excited State of Substituted Styrylpyrenes
In the equilibrium between trans (3t*) and perpendicular (3p*) conformers in the triplet excited state of 1-styrylpyrenes, substitution by electron-accepting groups at the para-position of styryl group more effectively stabilizes 3t* than 3p*, therefore affording very high composition of their trans isomers at the photostationary state.
Volume-Demanding Cis<i>−</i>Trans Isomerization of 1,2-Diaryl Olefins in the Solid State
作者:Arunkumar Natarajan、Joel T. Mague、K. Venkatesan、T. Arai、V. Ramamurthy
DOI:10.1021/jo0520644
日期:2006.2.1
Volume-demanding cis−trans photoisomerization of the aromatic substituted alkenes 1−3 in the solid state at room temperature and at 50 °C is presented. Alkene 3 did not undergo the cis−transisomerization in the solid state either at room temperature or at 50 °C. The importance of the presence of void space near the reaction center to facilitate the large volume change during cis−trans photoisomerization