Mothball macrocycles: Naphthalene has been coupled to form macrocylic oligomers composed of five, six, and seven naphthalene units (see picture). Thermally stable macrocycles bearing 50, 60, or 70 π electrons within the hydrocarbon structure form columnar assemblies in crystals and serve as bipolar carrier transport materials in organic light‐emitting diode devices.

Electronic states are calculated in boron carbonitride (BCN) alloy nanotubes with a simple tight-binding model. Random replacement of carbon atoms with boron and nitrogen (B-N) ones in metallic carbon nanotubes mainly causes level broadening and the nanotubes remain metallic. On the other hand, the energy gap of boron nitride (BN) nanotubes always survives under random substitution of B-N atoms by carbon ones while it becomes smaller than the original gap. Further, the optical gap does not correspond well with the band gap of the density of states in nanotubes with high B-N concentration. This can be understood in terms of localized states associated with carbon impurities in a BN nanotube.

Mottenkugel‐Makrocyclen: Naphthalin wurde zu makrocylischen Oligomeren aus fünf, sechs und sieben Naphthalineinheiten gekuppelt (siehe Bild). Die thermisch stabilen Makrocylen mit 50, 60 oder 70 π Elektronen in reinen Kohlenwasserstoffen bilden im Kristall säulenförmige Assoziate und dienen als bipolare Transportmaterialien für Träger in organischen Leuchtdioden.

Single crystals of a macrocyclic hydro­carbon, [6]cyclo-2,7-naphthyl­ene ([6]CNAP, C60H36) were prepared from anthracene melt with a prolonged time for the recrystallization. The crystal of improved quality led to the correction of the space-group assignment to Cmca from in the original determination [Nakanishi et al. (2011 ▶) Angew. Chem. Int. Ed. 50, 5323–5326] and the refinement of anisotropic displacement parameters of all C atoms. The refined mol­ecular structure with C 2h point symmetry indicated that the strain on the naphthyl rings of [6]CNAP is smallest among the congeners. Despite the large macrocyclic structure, mol­ecules are packed in a ubiquitous herringbone motif. A short C—C distance of 3.119 (4) Å was found in the stacking direction, and a short C—H distance of 2.80 Å was found in the inter­columnar contact.

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