Synthesis and properties of all-benzene carbon nanocages: a junction unit of branched carbon nanotubes

Abstract

The first synthesis of an all-benzene carbon nanocage 1, which represents a junction unit of branched carbon nanotubes, has been achieved. A stepwise assembly of six L-shaped units [cis-di(p-bromophenyl) cyclohexane derivative] and two three-way units (1,3,5-triborylbenzene) by cross-coupling and homocoupling provided the unstrained cyclic precursor. Acid-mediated aromatization of cyclohexane moieties in the precursor resulted in the formation of carbon nanocage 1. Photophysical measurements and DFT studies revealed the unique properties of 1, such as D 3 symmetry with degenerate HOMO/ HOMO À 1 and LUMO/LUMO + 1, high fluorescence quantum yield (F F ¼ 0.87), and a relatively large two-photon absorption cross section (500 GM at 590 nm), which are attractive for various applications.

Design and Synthesis of Carbon Nanotube Segments

“…[74] Similar to Itamis synthesis of U-shaped units for [14]- [16]CPPs from diborylbenzene and L-shaped units,t rifurcated unit 166 was obtained by at hreefold Suzuki-Miyaura coupling of 1,3,5-triborylbenzene with L-shaped unit 59 b.N ickel-mediated dimerization of 166 provided an unstrained bicyclic precursor 167,w hose six cyclohexanem oieties were subsequently aromatized to afford the [6.6.6]carbon nanocage 163. 164 and 165).…”

All-Benzene Carbon Nanocages: Size-Selective Synthesis, Photophysical Properties, and Crystal Structure

“…Through this synthetic route, [6.6.6]carbon nanocage (3) was successfully synthesized. 17 To synthesize smaller carbon nanorings (1 and 2), a phenylcyclohexanone derivative was chosen for the small bent unit (eq 4).…”

“…16 In 2012, we designed and proposed all-benzene carbon nanocages, three-dimensional cage-shaped conjugated hydrocarbons consisting solely of sp 2 -carbons and covalent bonds, as a new family of molecular nanocarbons (Figure 1). 17 The [n.n.n]carbon nanocages consist of three [n]paraphenylene bridges connected by two benzene-1,3,5-triyl bridgeheads. As carbon nanocages represent junction units of branched CNTs (Figure 1), the conditions we developed for CPP-to-CNT (ring-to-tube) conversion could be applied for the bottom-up synthesis of branched CNTs using carbon nanocages as templates.…”

Synthesis and physical properties of a ball-like three-dimensional π-conjugated molecule

“…While this work was ongoing, Matsui et al 40 reported on the synthesis of a p-conjugated 3D molecule that possessed a simpler bicyclic structure than 3, which is tricyclic, using a modification of the strategy they developed for CPP synthesis. However, the synthesis required long reaction steps and the final product was only obtained in a low overall yield.…”