On the Condensed Phase Ring-Closure of Vinylheptafulvalene and Ring-Opening of Gaseous Dihydroazulene

详细信息    查看全文

• 作者：Oliver Schalk ; S酶ren L. Broman ; Michael 脜. Petersen ; Dmitry V. Khakhulin ; Rasmus Y. Brogaard ; Mogens Br酶ndsted Nielsen ; Andrey E. Boguslavskiy ; Albert Stolow ; Theis I. S酶lling
• 刊名：The Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：April 25, 2013
• 年：2013
• 卷：117
• 期：16
• 页码：3340-3347
• 全文大小：401K
• 年卷期：v.117,no.16(April 25, 2013)
• ISSN：1520-5215

文摘

Dihydroazulenes are interesting because of their photoswitching behavior. While the ring-opening to vinylheptafulvalene (VHF) is light induced, the back reaction is known to proceed thermally. In the present paper, we show the first gas phase study of the ring-opening reaction of 2-phenyl-1,8a-dihydroazulene-1,1-dicarbonitrile (Ph-DHA) by means of time-resolved photoelectron spectroscopy which permits us to follow the ring-opening process. Moreover, we investigated s-trans-Ph-VHF in a series of transient absorption experiments, supported by ab initio computations, to understand the origin of the absence of light-induced ring-closure. The transient absorption results show a biexponential decay governed by a hitherto unknown state. This state is accessed within 1鈥? ps and return to the ground state is probably driven through a cis鈥搕rans isomerization about the exocyclic C₁鈺怌₂ double bond. The rapid decrease in potential energy disfavors internal rotation to s-cis-Ph-VHF, the structure that would precede the ring-closure reaction.