The Precise Synthesis of Phenylene‐Extended Cyclic Hexa‐peri‐hexabenzocoronenes from Polyarylated [n]Cycloparaphenylenes by the Scholl Reaction

Abstract

The longitudinal extension of cycloparaphenylenes (CPP) towards ultrashort carbon nanotubes (CNTs) is essential for the solution based bottom-up synthesis of CNTs. Herein, the longitudinal extension of the CPP skeleton by the introduction of hexaphenylbenzene units towards polyarylated [n]CPPs is described. Further, the applicability of the Scholl reaction to selectively form graphenic sidewalls is demonstrated. The ring size and substitution patterns of the polyarylated [n]CPPs were varied to overcome strain-induced side reactions during the oxidative cyclodehydrogenation and cyclic para-hexa-peri-hexabenzocoronene trimers ([3]CHBCs) were selectively obtained. This concept is envisioned as an access to ultrashort carbon nanotubes subject to the condition that further benzene rings with the right connectivity will be inserted.

Dibenzo[a,e]pentalenophanes: Bending a Non‐Alternant Hydrocarbon

“…Of the large number of reported cyclophanes, however, only few contain polycyclic aromatic hydrocarbons (PAHs) consisting of at least four annulated rings . Examples of such incorporated PAHs are pyrene, corannulene, acenes, teropyrene, and hexabenzocoronene . These cyclophanes are of particular interest as model systems for bent carbon nanostructures such as carbon nanotubes, in some cases representing subunits thereof .…”

π-extended [12]cycloparaphenylenes: from a hexaphenylbenzene cyclohexamer to its unexpected C2-symmetric congener

“…15 For 2 , a loss of 20 hydrogen atoms of a possible 96 was observed by MALDI-MS, at which the cyclodehydrogenation came to a halt, despite prolonged reactions times. In contrast to our previous results, here we could, for the first time, determine the degree of cyclodehydrogenation due to isotopically resolved mass peaks.…”

Armchair and Chiral Carbon Nanobelts: Scholl Reaction in Strained Nanorings

“…Indeed, within the multiple applications envisaged for hybrid perovskites-ranging from lasers 2 to radiation detectors 3 to light-emitting diodes 4 -the use of these novel materials for efficient solar cells is the topic that has attracted the most consideration. 5 Nonetheless, the optoelectronic properties of the hybrid-perovskite-like methylammonium lead halide perovskite (MAPI) presents novel opportunities for applications closer to market applications. For instance, MAPI shows an excellent lightabsorption coefficient and outstanding carrier lifetimes 6 approaching the values of the current materials used as photodetectors in commercial applications.…”

“…In 2015, the Mü llen group reported the unsuccessful Scholl reaction of poryarylated [15]-and [21]CPPs for the construction of hexabenzocoronene structures ( Figure 1A). 5 Instead of the desired product, 1,2-rearranged meta-linkage rings, in which rearrangement had occurred to relieve the ring strain, were obtained. The Jasti group also attempted a similar Scholl reaction of tetraarylated [12]CPP, but the products were a complex mixture ( Figure 1B).…”

“…Notably, in this synthesis, the Scholl reaction in the CNR precursors worked well, unlike in previous reports. 5,6 The authors commented that the key to a successful Scholl reaction is the low reaction temperature (-78 C) to prevent undesired rearrangement and the introduction of propoxy groups to facilitate the cyclization by lowering oxidation potential. Additionally, the authors achieved the first synthesis of a chiral (18,12)CNB by the Scholl reaction from a chiral-type CNR, the derivative of cycloparaphenylene-2,6-naphthylene ( Figure 1E).…”