Phenylene segments of zigzag carbon nanotubes synthesized by metal-mediated dimerization

Synthesis and Characterization of a Non-Planar Cyclophenylene on Au(111)

We report the surface-assisted synthesis of a non-planar cyclophenylene derivative containing four meta- and two para- connected phenylene moieties on Au(111), via hierarchical Ullmann coupling of a 1,10-dibrominated angular [3] phenylene and subsequent C-C bond cleavage at the four-membered rings. Scanning tunneling microscopy and spectroscopy (STM/STS) were used for the characterization of its chemical structure and electronic properties. Density functional theory (DFT) calculations support the experimental observations.

A Helical Tubular Dyad of [9]Cycloparaphenylene: Synthesis, Chiroptical Properties and Post-Functionalization

The bottom-up synthesis of discrete tubular molecules that mimic the structural features of carbon nanotubes has been a long-standing pursuit for synthetic chemists. As the shortest segments of armchair-type carbon nanotubes, cycloparaphenylenes are regarded as ideal macrocyclic building blocks for achieving this goal. Here we report the synthesis of a helical tubular molecule featuring three diyne linkers between two site-specifically functionalized [9]cycloparaphenylenes. Its C3-symmetrical, radially conjugated structure and solid-state packing have been elucidated by spectroscopic and crystallographic characterizations. Notably, the resolved enantiomers display a circularly polarized luminescence brightness value of 1.47×103 M-1 cm-1, which is among the highest values for chiral organic molecules. Furthermore, the diyne-linked molecule could be directly converted into a thiophene-linked helical molecule, demonstrating the post-functionalization approach for the construction of chiral tubular molecules from cycloparaphenylenes.

Complexation study of a 1,3-phenylene-bridged cyclic hexa-naphthalene with fullerenes C60 and C70 in solution and 1D-alignment of fullerenes in the crystals

To investigate the host ability of a simple macrocycle, 1,3-phenylene-bridged naphthalene hexamer N6, we evaluated the complexation of N6 with fullerenes in toluene and in the crystals. The complexes in the solid-state demonstrate the one-dimensional alignment of fullerenes. The single-crystals of the C60@N6 composite have semiconductive properties revealed by photoconductivity measurements.

Stable Crystalline Nanohoop Radical and Its Self-Association Promoted by van der Waals Interactions

A stable nanohoop radical (OR3) combining the structures of cycloparaphenylene and an olympicenyl radical is synthesized and isolated in the crystalline state. X-ray crystallographic analysis reveals that OR3 forms a unique head-to-tail dimer that further aggregates into a one-dimensional chain in the solid state. Variable-temperature NMR and concentration-dependent absorption measurements indicate that the π-dimer is not formed in solution. An energy decomposition analysis indicates that van der Waals interactions are the driving force for the self-association process, in contrast with other olympicenyl derivatives that favor π-dimerization. The physical properties in solution phase have been studied, and the stable cationic species obtained by one-electron chemical oxidation. This study offers a new molecular design to modulate the self-association of organic radicals for overcoming the spin-Peierls transition, and to prepare novel nanohoop compounds with spin-related properties.