[<i>n</i>]Helicene Diimides (<i>n</i> = 5, 6, and 7): Through-Bond versus Through-Space Conjugation
Fridolin Saal, Fangyuan Zhang, Marco Holzapfel, Matthias Stolte, Evripidis Michail, Michael Moos, Alexander Schmiedel, Ana‐Maria Krause, Christoph Lambert, Frank Würthner, Prince Ravat
Abstract
The interactions between auxochromic groups in π-conjugated functional molecules dictate their electronic properties. From the standpoint of potential applications, understanding and control of such interactions is a vital requirement for the material design. In this communication, we describe the design, synthesis, and functional properties of a novel class of helically chiral diimide molecules, namely, [n]HDI-OMe (n = 5, 6, and 7), in which two imide units are connected via an [n]helicene skeleton. The experimental results supported by quantum chemical calculations reveal that the helical backbone in these molecules offers not only through-bond but also through-space conjugation between imide groups, which leads to distinct optical and electrochemical properties when compared to the related [n]helicenes and rylene diimides.