Synthesis, computational, and photophysical characterization of diaza-embedded [4]helicenes and pseudo[4]helicenes and their pyridinium and viologen homologues

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• 作者：Xiaoping Zhang ; Edward L. Clennan ; ^{clennane@uwyo.edu} ; Toby Petek ; Jacob Weber
• 关键词：Helicenes ; Viologens ; Photophysics ; Computational chemistry ; Racemization barriers
• 刊名：Tetrahedron
• 出版年：2017
• 出版时间：2 February 2017
• 年：2017
• 卷：73
• 期：5
• 页码：508-518
• 全文大小：1293 K
• 卷排序：73

文摘

Synthesis of three [4]heli-viologens and their helical precursors, and two “pseudo-[4]helicenes” and their alkylated derivatives, which have potential device and catalysis applications, are reported. Their structures and racemization barriers have been explored with the B3LYP/6-311+G(2d,p), M06-2X/6-311+G(2d,p), and M11/6-311+G(2d,p) computational models. The photophysical properties of the helicenes and pseudo-helicenes and their alkylated derivatives have been measured. Unusual singlet-triplet energy gaps, ΔEST, were measured and discussed for the charged alkylation products.