Chiral Conjugated Corrals

Abstract

We present here a new design motif for strained, conjugated macrocycles that incorporates two different aromatics into the cycle with an -A-B-A-B- pattern. In this study, we demonstrate the concept by alternating electron donors and acceptors in a conjugated cycle. The donor is a bithiophene, and the acceptor is a perylene diimide derivative. The macrocycle formed has a persistent elliptiform cavity that is lined with the sulfur atoms of the thiophenes and the π-faces of the perylene diimide. Due to the linkage of the perylene diimide subunits, the macrocycles exist in both chiral and achiral forms. We separate the three stereoisomers using chiral high-performance liquid chromatography and study their interconversion. The mechanism for interconversion involves an "intramolecular somersault" in which one of the PDIs rotates around its transverse axis, thereby moving one of its diimide heads through the plane of the cavity. These unusual macrocycles are black in color with an absorption spectrum that spans the visible range. Density functional theory calculations reveal a photoinduced electron transfer from the bithiophene to the perylene diimide.

Design and Synthesis of Carbon Nanotube Segments

“…Thep reviously presented synthetic strategies for the generation of [n]CPPs can also be applied for the synthesis of av ariety of other strained ring-shaped compounds.W hen substituted benzene rings (e.g.tetraphenylbenzene), polycyclic aromatic hydrocarbons (e.g.n aphthalene,p yrene,o r chrysene), or heteroarenes (e.g.p yridine, [44] thiophene, [45] anthraquinone, [46] carbazole, [47] or perylene diimide [48] )a re used in addition to benzene rings,C PP derivatives called "carbon nanorings" are obtained. Soon after the development of suitable synthetic methods for the generation of [n]CPPs by the groups of Jasti, Itami, and Yamago ( Figure 7), avariety of carbon nanorings were synthesized by these and other groups.…”

Pentagon‐Embedded Cycloarylenes with Cylindrical Shapes

“…Theconstruction of conjugated p-systems on unique hexagonal networks of sp 2 -hybridized carbon atoms has been demonstrated, producing nanocarbon models with discrete structures. [12][13][14] Synthetically,afew examples of pentagon-embedded nanohoops have been realized in forms of heteroaromatic curved p-systems, [15][16][17][18][19] but the incorporation of pentagons into the curved conjugated systems of cylinder-shaped molecules with sp 2 -carbon networks has not been achieved. [3,4] In contrast, odd-numbered polygonal rings, such as pentagons and heptagons,a re much less explored in nanocarbon structures.Although pentagons and/or heptagons were initially perceived as structural defects that distort the nanocarbon shapes, [5][6][7][8][9] recent theoretical investigations indicate that odd-numbered rings could also give rise to flat or curved nanocarbon sheets through anomalous periodic arrangements.F or instance,p entagon/heptagon-containing cylinders of sp 2 -carbon networks,s uch as pentaheptite and haeckelite (Figure 1), [10,11] have been proposed, and their unique conjugated systems with enhanced metallic character have been extensively discussed in the context of novel tubular nanocarbon materials.Avariety of cylinder-shaped nanocarbon structures are currently being exploited to dramatically expand the theoretical models of cylindershaped nanocarbons with odd-numbered rings.…”

Design und Synthese von Kohlenstoffnanoröhrensegmenten

“…B. Pyridin, [44] Thiophen, [45] Anthrachinon, [46] Carbazol [47] oder Perylendiimid [48] )zusätzlich zu Benzolringen verwendet, lassen sich als "Kohlenstoffnanoringe"b ezeichnete CPP-Derivate erhalten. Werden substituierte Benzolringe (z.…”