2,11-Dibromo-5,8-dibut­yl[4]helicene

A racemic mixture of the title compound, C26H26Br2, a brominated [4]helicene, crystallizes, forming columns of stacked mol­ecules. There are two crystallographically unique mol­ecules in the asymmetric unit, both with the same helical handedness. As is typical with helicene congeners, the unique mol­ecules show short inter­atomic contacts between H atoms at the fjord region, with H⋯H distances of 1.87 and 1.94 Å. Mol­ecules with the same helical handedness segregate in the crystal packing, forming homochiral columns. The stacked mol­ecules are piled in a column with alternate orientations. The shortest C⋯C distance in the stacked mol­ecules is 3.306 (4) Å

1,8-Diiodo­anthracene

The mol­ecule of the title compound, C14H8I2, an inter­mediate in the synthesis of organic materials, is nearly planar, the maximum deviation from the mean plane being 0.032 (1) Å for the C atoms and 0.082 (2) Å for the I atoms. In the crystal structure, a sandwich–herringbone arrangement of mol­ecules is observed, whereas a columnar π-stacking arrangement has been reported for the chlorinated congener 1,8-dichloro­anthracene. Similar effects of halogen substituents on the modulation of packing arrangements are reported for halogenated aromatic compounds such as tetra­cenes and chrycenes

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

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

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