Tetrameric ααββ Aggregate Formation by Stereoisomeric Bidomain Helicene Oligomers

Abstract

Für mehr Zusammenhalt: Tetramere Aggregate mit ααββ‐Struktur können mithilfe stereoisomerer Zwei‐Domänen‐Oligomere erhalten werden. Mischen der Oligomere liefert das ααββ‐Aggregat durch Heteroaggregation an der Ethinyl‐Domäne. Erhitzen und Abkühlen setzen das tetramere Aggregat in ein reversibles Gleichgewicht mit den dimeren Homoaggregaten, während in Toluol eine Polymerisation unter Gelbildung erfolgt.

Aromatic Superhalogens

“…Helicenes, as a member of polycyclic aromatic hydrocarbons formed by ortho ‐annulated aromatic or heteroaromatic rings, have attracted increasing interest because of their conjugated skeletons and intriguing helical chirality 5. Recently, optically pure helicenes having diverse functional groups are employed in several different fields, such as high‐optical‐rotation complexes,6 organoelectronics,7 asymmetric gold catalysis,8 redox‐triggered chiroptical switches,9 and proteinlike tetrameric ααββ‐heteroaggregates 10. Although the stereoselective synthesis of helicenes has been realized by virtue of organometallic catalysis11 and Diels–Alder additions12 during the last decade, most of the helicenes employed in optically active forms, as in asymmetric synthesis13 and self‐assembly,14 were resolved by semi‐preparative or preparative high performance liquid chromatography (HPLC), which is an expensive and impractical strategy.…”

Energy Aspects of Thermal Molecular Switching: Molecular Thermal Hysteresis of Helicene Oligomers

“…For example, 1) large structural changes on theo rder of nanometers occur;2 )the involvement of both intra-and intermoleculari nteractions betweenl arge molecular surfaces results in novel switching properties;a nd 3) ordered molecular assemblies can be constructed by using synthetic oligomers to integrate molecular switching into large materials, that is, on the order of micro-to millimeters. [17] For variousm olecular switching systemsa nd synthetic oligomers developed by other groups,s uggested reviews are summarized in the reference section. [1, 3, 16d]…”

Dioxygen‐Triggered Transannular Dearomatization of Benzo[5]helicene Diols: Highly Efficient Synthesis of Chiral π‐Extended Diones

“…[5] Recently, optically pure helicenes having diverse functional groups are employed in several different fields, such as highoptical-rotation complexes, [6] organoelectronics, [7] asymmetric gold catalysis, [8] redox-triggered chiroptical switches, [9] and proteinlike tetrameric aabb-heteroaggregates. [10] Although the stereoselective synthesis of helicenes has been realized by virtue of organometallic catalysis [11] and Diels-Alder additions [12] during the last decade, most of the helicenes employed in optically active forms, as in asymmetric synthesis [13] and self-assembly, [14] were resolved by semi-preparative or preparative high performance liquid chromatography (HPLC), which is an expensive and impractical strategy. It has been a significant challenge to find a convenient and efficient strategy to obtain optically pure helicenes.…”