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

[6]Cyclo-2,7-naphthyl­ene: a redetermination

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

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

Diels-Alder reactions using 4,7-dioxygenated indanones as dienophiles for regioselective construction of oxygenated 2,3-dihydrobenz[f]indenone skeleton

Regioselective construction of 4,8,9-trioxygenated 2,3-dihydrobenz[f]indenones, key intermediates for the synthesis of kinamycin antibiotics, was achieved via Diels-Alder reactions (DAR) using 4,7-dioxygenated indanone-type compounds as dienophiles. Reaction of indanetrione with 1-methoxybutadiene gave a 1 : 1 mixture of undesired 4,5,9-trioxygenated 2,3-dihydrobenz[f]indenone and [4.4.3]propellane. The addition of Lewis acid did not affect the product ratio, whereas the use of the 6-bromoindanetrione exclusively afforded the latter propellane. On the other hand, DAR of benzyne derived from bromoindan and furan gave 5,8-epoxy-2,3-dihydrobenz[f]indene, which was subjected to acid-induced ring opening to give 2,3-dihydrobenz[f]indenone with undesired 4,5,9-trioxy functions

Driving nanocars and nanomachines at interfaces: From concept of nanoarchitectonics to actual use in world wide race and hand operation

cited By 9International audienceNanomachine and molecular machines are state-of-the-art objects in current physics and chemistry. The operation and manufacturing of nanosize machines are top-level technologies that we have desired to accomplish for a long time. There have been extensive attempts to design and synthesize nanomachines. In this paper, we review the these attempts using the concept of nanoarchitectonics toward the design, synthesis, and testing of molecular machinery, especially at interfacial media. In the first half of this review, various historical attempts to design and prepare nanomachines are introduced as well as their operation mechanisms from their basic principles. Furthermore, in order to emphasize the importance and possibilities of this research field, we also give examples of two new challenging topics in the second half of this review: (i) a world wide nanocar race and (ii) new modes of nanomachine operation on water. The nanocar race event involves actual use of nanomachines and will take place in the near future, and nanomachine operation of a dynamic fluidic interface will enable future advances in nanomachine science and technology