Photophysical and Electrochemical Characterization of a Helical Viologen, N,N鈥?Dimethyl-5,10-diaza[5]helicene

详细信息    查看全文

• 作者：Xiaoping Zhang ; Edward L. Clennan ; Navamoney Arulsamy
• 刊名：Organic Letters
• 出版年：2014
• 出版时间：September 5, 2014
• 年：2014
• 卷：16
• 期：17
• 页码：4610-4613
• 全文大小：252K
• ISSN：1523-7052

文摘

The first helical viologen (4,4鈥?bipyridinium salt) has been prepared and characterized. Its reduction to the radical cation at 鈭?.22 V vs SCE makes it the most easily reduced redox-active helicene known. It exhibits absorption at 397 nm for the S₁ 鈫?S₀ transition, and it is luminescent allowing measurement of both its singlet (59.3 卤 0.1 kcal/mol) and triplet (54 卤 1 kcal/mol) energies. In contrast to neutral helicenes, it is not aromatic 蟺-stacked in the crystal and has a shortest interdication distance of 4.977 脜. Its racemization barrier is calculated to be a sensitive function of its redox state.