C- and S-Shaped Perylene Diimide Heterohelicenes: Modular Synthesis and Spiral-Stair-Like π-Stacking

Abstract

A number of C- and S-shaped perylene diimide (PDI) heterohelicenes with high dipole moments were synthesized from simple perylene tetrabutylester (PTE). Taking advantage of the weak coordination ability of the sterically crowded peri ester groups in PTE, efficient Rh­(III)-catalyzed 2,8- and 2,11-bisiodinations of the perylene core were realized. The 2,8- and 2,11-diiodinated PTEs and PDIs represent key synthons for further ortho-π-extensions. In contrast to most helical π-skeletons that feature loose molecular packings, enantiomerically pure C-shaped PDI azahelicenes adopt unique spiral-stair-like π-stacking superstructures.

Peri‐Decoration of a Tetraazaperylene with Urea Units: Chiral Octaazaperopyrenedioxides (OAPPDOs) and Their Optical and Chiroptical Properties

“…The steric repulsion of the aryl substituents in the bay position leads to the twist of the perylene core and consequently, to the formation of helically chiral structures [49,53, 57–58,59] . There are thus two atropisomers ( P and M ) of compounds 6 a – e .…”

“…The steric repulsion of the aryl substituents in the bay position leads to the twist of the perylene core and consequently, to the formation of helically chiral structures. [49,53,[57][58]59] There are thus two atropisomers (P and M) of compounds 6 a-e. Due to this helical chirality, the proton signals of the bay aryl units in the 1 H NMR spectra are not equivalent and appear separated at low temperature (Figure 3, À 30 °C). At temperatures below À 30 °C, the exchange of the ortho protons was frozen due to the decelerated rotation of the aryl unit, resulting in two different signals for the ortho protons (7.43 and 6.90 ppm).…”

New advances in chiral nanographene chemistry

“…10). 74 Single crystals of both structures were obtained as racemic mixtures, confirming the chiral nature of the structures. The enantiomers for the C-shaped structure 60 were separable by chiral HPLC, and appeared to be remarkably conformationally stable, with no observable changes in the CD spectra after heating an enantiopure sample to 250 °C.…”

Frustrated π-stacking

“…Guided by this strategy, we recently developed an efficient rhodiumcatalyzed ortho-iodination reaction of PDIs (Scheme 2). 42,43 This method enables the synthesis of various ortho-functionalized PDI derivatives without distorting the planarity of the PDI skeleton. By introducing branched alkyl groups at the imide positions, a considerable amount of steric hindrance is introduced.…”