Bottom-up Synthesis and Thread-in-Bead Structures of Finite (<i>n</i>,0)-Zigzag Single-Wall Carbon Nanotubes

The last remaining synthetic target of finite single-wall carbon nanotube models, the zigzag nanotube, has been accomplished through bottom-up chemical synthesis. The zigzag nanotube was synthetically accessible without constructing long-sought yet elusive cyclacene structures but with a cycloarylene structure by devising its cutout positions. The persistent tubular shape was also perfected in this last model by cyclization of zigzag-shaped aromatic molecules with a synchronous topological arrangement. The crystal structure of this nanotube further revealed an entangled supramolecular assembly, which showed a novel way to align nanotube molecules by utilizing their open-end functional groups in a thread-in-bead molecular assembly

Bottom-up Synthesis and Thread-in-Bead Structures of Finite (<i>n</i>,0)-Zigzag Single-Wall Carbon Nanotubes

The last remaining synthetic target of finite single-wall carbon nanotube models, the zigzag nanotube, has been accomplished through bottom-up chemical synthesis. The zigzag nanotube was synthetically accessible without constructing long-sought yet elusive cyclacene structures but with a cycloarylene structure by devising its cutout positions. The persistent tubular shape was also perfected in this last model by cyclization of zigzag-shaped aromatic molecules with a synchronous topological arrangement. The crystal structure of this nanotube further revealed an entangled supramolecular assembly, which showed a novel way to align nanotube molecules by utilizing their open-end functional groups in a thread-in-bead molecular assembly

Enhanced yet Inverted Effects of π‑Extension in Self-Assembly of Curved π‑Systems with Helicity

A sextuple helix molecule possessing four cove regions of helicene and two axes of biaryls was synthesized. The entropy-driven self-assembly in solution was determined by concentration- and temperature-dependent NMR spectra, which also revealed unique dynamics of isomerization involving structural changes at the cove regions. Unexpectedly, the assembly retarded the isomerization in solution, and the sextuple helix structure was rigidified

Entropy-Driven Ball-in-Bowl Assembly of Fullerene and Geodesic Phenylene Bowl

Complexation of C₆₀ at a conical region of a nanometer-sized geodesic phenylene bowl has been demonstrated. Proton NMR spectroscopy showed formation of a 1:1 complex that was driven by entropy gains for the assembly. Crystallographic analyses revealed its unique ball-in-bowl structure, and the presence of smoothly curved surfaces was unveiled at their interfaces

Entropy-Driven Ball-in-Bowl Assembly of Fullerene and Geodesic Phenylene Bowl

Complexation of C₆₀ at a conical region of a nanometer-sized geodesic phenylene bowl has been demonstrated. Proton NMR spectroscopy showed formation of a 1:1 complex that was driven by entropy gains for the assembly. Crystallographic analyses revealed its unique ball-in-bowl structure, and the presence of smoothly curved surfaces was unveiled at their interfaces

Assessment of Fullerene Derivatives as Rolling Journals in a Finite Carbon Nanotube Bearing

Conformance assessment of rolling journals in a molecular bearing has been carried out with a combination of fullerenes and finite single-wall carbon nanotube molecules through quantitative analysis of the binding affinities. Endohedral fullerenes were applicable to three-body molecular bearings with slightly weaker binding affinities. Exohedral shaft moieties on C₆₀ journals affected the binding affinities to reduce the binding constants to a considerable extent, and oval-spherical C₇₀ journals were superior in tolerating bulky shaft attachments

Asymmetric Autocatalysis Initiated by Finite Single-Wall Carbon Nanotube Molecules with Helical Chirality

An asymmetric autocatalysis reaction was initiated by a finite single-wall carbon nanotube molecule with helical chirality. The asymmetric induction was initiated by the chiral environment arising from the planar chirality of the tubular polyaromatic hydrocarbons

Stereoisomerism in Nanohoops with Heterogeneous Biaryl Linkages of <i>E/Z</i>- and <i>R/S</i>-Geometries

The stereochemistry of cycloarylene nanohoops gives rise to unique cyclostereoisomerism originating from hoop-shaped molecular shapes. However, cyclostereoisomerism has not been well understood despite the ever-increasing number of structural variants. The present work clarifies the cyclostereoisomerism of a cyclophenanthrenylene nanohoop possessing both <i>E/Z</i>- and <i>R/S</i>-geometries at the biaryl linkages. Involvement of the <i>R/S</i> axial chirality in the nanohoop leads to the deviation of the structure from a coplanar belt shape and allows for structural variations with 51 stereoisomers with <i>E/Z</i>- and <i>R/S</i>-geometries. Experimental investigations of the dynamic behaviors of the cyclophenanthrenylene nanohoop revealed the presence of two-stage isomerization processes taking place separately at the <i>E/Z</i>- and <i>R/S</i>-linkages. Consequently, despite the presence of <i>E/Z</i>-fluctuations, the <i>R/S</i> axial chirality resulted in a separable pair of enantiomers. The structural information reported here, such as geometric descriptors and anomalous dynamics, may shed light on the common structures of various nanohoops

Cyclo‑<i>meta</i>‑phenylene Revisited: Nickel-Mediated Synthesis, Molecular Structures, and Device Applications

From a one-pot nickel-mediated Yamamoto-type coupling reaction of <i>m</i>-dibromobenzene, five congeners of [<i>n</i>]­cyclo-<i>meta</i>-phenylenes were synthesized and fully characterized. The [<i>n</i>]­cyclo-<i>meta</i>-phenylenes possessed a commonly shared arylene unit and intermolecular contacts but varied in packing structures in the crystalline solid state. Columnar assembly of larger congeners yielded nanoporous crystals with carbonaceous walls to capture minor protic or aliphatic solvent molecules. The concise and scalable synthesis allowed exploration of the macrocyclic hydrocarbons as bipolar charge carrier transport materials in organic light-emitting diode devices

Photoinduced Electron Transfer in a Dynamic Supramolecular System with Curved π‑Structures

Photoinduced electron-transfer processes in a carbonaceous supramolecular combination of a tubular host and a C₆₀ guest were investigated with time-resolved transient absorption spectra upon laser flash photolysis. Following the formation of triplet charge-separated species via electron transfer from the host to the guest, a rapid back electron transfer proceeded to afford triplet C₆₀