详细信息    查看全文

• 作者：Jaan Laane ; Eugene Bondoc ; Sachie Sakurai ; Kevin Morris ; Niklas Meinander ; and Jaebum Choo
• 刊名：Journal of the American Chemical Society
• 出版年：2000
• 出版时间：March 22, 2000
• 年：2000
• 卷：122
• 期：11
• 页码：2628 - 2634
• 全文大小：113K
• 年卷期：v.122,no.11(March 22, 2000)
• ISSN：1520-5126

文摘

The electronic absorption spectra and the laser-induced fluorescence spectra of supersonic-jet-cooled1,3-benzodioxole molecules have been investigated to map out the vibronic energy levels in the S₁(s/gifchars/pi.gif" BORDER=0 >,s/gifchars/pi.gif" BORDER=0 >*)electronic excited state. These were used to determine a two-dimensional potential energy surface in terms ofthe ring-puckering and ring-flapping vibrational coordinates, and the molecule was found to be puckered witha dihedral angle of 22s/entities/deg.gif">. The barrier to planarity in the excited state is 264 cm^-1 (3.16 kJ/mol) as compared to164 cm^-1 (1.96 kJ/mol) in the ground state. This increase is attributed to reduced suppression of the anomericeffect by the benzene ring resulting from decreased s/gifchars/pi.gif" BORDER=0 > bonding character in the S₁(s/gifchars/pi.gif" BORDER=0 >,s/gifchars/pi.gif" BORDER=0 >*) state. As expected,the motion along the flapping coordinate is governed by a more shallow potential energy well. Ab initiocalculations carried out for both the ground and excited states support the experimental conclusions.