Synthesis and Chiral Resolution of Twisted Carbon Nanobelts

Abstract

Twisted carbon nanobelts could display persistent chirality, which is desirable for material applications, but their synthesis is very challenging. Herein, we report the successful synthesis and chiral resolution of such a kind of molecules (1-H and 1) with a figure-eight configuration. 1-H was synthesized first by macrocyclization through Suzuki coupling reaction followed by benzannulation via Bi­(OTf)3-mediated cyclization reaction of vinyl ether. Oxidative dehydrogenation of 1-H gave the fully π-conjugated 1. Their twisted structures were confirmed by X-ray crystallographic analysis and calculations, and they can be resolved by chiral high-performance liquid chromatography. The isolated enantiomers showed persistent chiroptical properties according to the circular dichroism measurements, with moderate |g abs| values (0.0016 for 1-H and 0.005–0.007 for 1). Their photophysical properties were also briefly studied.

Non-intersecting ring currents in [12]infinitene

“…[12]Infinitene does not obey the Mo ¨bius and Hu ¨ckel aromaticity rules, since it is not an annulene but a polyarylene with two nearly independent ring-current pathways suggesting that 4n p electrons lead to aromaticity. The aromaticity of new twisted structures [47][48][49] must be addressed carefully, taking into consideration the magnetic response properties, since counting the number of p electrons in the delocalization pathway may lead to incorrect conclusions concerning their aromatic character. 1 Ring-current strengths (in nA/T) of (P,P)-infinitene (neutral and dication) divided into their diatropic and paratropic components calculated at the CAM-B3LYP/def2-TZVP level when the external field points parallel to z axis.…”

Molecular Carbon Imides

“…First, from bay fusion with [6]helicene, the stereoisomerization of bay dibrominated PDIs led to a configurational diversity of six stereoisomers of PDI-embedded double [8]helicenes, including two pairs of enantiomers (M,M-and P,P-23; M,M-and P,P-24) and two mesomers (M,P-23 and M,P-24). 90 Subsequently, PDI-embedded double S- [5]helicene (25) has been obtained by the combination of Sonogashira coupling at ortho sites and quadruple thienannulation. 91 Similarly, annulation of four indole rings through ortho nucleophilic aromatic substitution and then Pd-catalyzed dehydrohalogenation to generate PDI-embedded double N- [5]helicenes in moderate yields was also achieved by us and Lin, individually.…”

“…Cycloparaphenylenes (CPPs), as the representative carbon nanorings, mainly developed by Jasti, Itami, and Yamago, are the shortest armchair ( n , n )­CNT segments. Meanwhile, Müllen and co-workers reported ground-breaking work on the precise synthesis of structurally well-defined graphene nanoribbons (GNRs) with widths of 0.69–1.13 nm and lengths of over 200 nm via linear extension of PAHs (e.g., hexa- peri -hexabenzocoronene ( p -HBC)). − Motivated by this, a wealth of elegant molecular carbons, such as flat or warped nanographene (e.g., PAHs and GNRs), − ring-shaped molecules (e.g., carbon nanorings, carbon nanobelts, and carbon nanohoops), − and bowl-shaped molecules (e.g., carbon end-caps) − attracted unprecedented attention from organic and materials chemists (Figure ).…”

Synthesis of Defective Nanographenes Containing Joined Pentagons and Heptagons

“…[ 116 ] The key intermediate 156 can be prepared through iridium‐catalyzed borylation and Suzuki coupling, and it is transferred to a mixture of methyl vinyl ester 157 by a typical Wittig reaction, followed by bismuth‐mediated cyclization in a quite high yield of 99% under mild conditions. It is worth noting that this bismuth‐mediated cyclization and aromatization have been powerful tools for the construction of phenacene‐like structures in nanoring and helicene chemistry [ 117 , 118 , 119 ] since their first discovery in 2014. [ 120 ] Following a similar procedure, extended nanographenes 159 and 160 were obtained successfully.…”