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

Abstract

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.

Chemical Reduction of a Nanosized [6]Cyclo‐2,7‐naphthylene Macrocycle

“…The crystal structure of solvent‐free [6]CNAP (C 60 H 36 , 1 ) was reported back in 2011 using crystallization from anthracene melt ( 1‐a ) [15, 18] . In 2016, a solvent‐containing polymorph, C 60 H 36 ⋅C 6 H 4 Cl 2 ( 1‐b ), was reported [7b] .…”

Carbon‐Rich Active Materials with Macrocyclic Nanochannels for High‐Capacity Negative Electrodes in All‐Solid‐State Lithium Rechargeable Batteries

“…Upon sublimation of r‐[6]CNAP at 883 K under 10 −2 Pa, the solvent molecules were completely removed, and the s‐[6]CNAP powder existed in a pristine form. We note that a solvent‐free specimen has also been obtained by high‐temperature recrystallization from anthracene melt …”

“…Although diffraction analysis of the s‐[6]CNAP powder was not successful with ordinary X‐ray beams, the structure was successfully solved at the atomic level (0.93 Å resolution, R wp = 1.8%) with the aid of a synchrotron beamline equipped with a Debye–Scherrer camera (BL02B2, SPring‐8) . As shown in Figure b, the naphthylene panels were tilt‐aligned in a herringbone‐like motif, and the macrocyclic opening of one molecule was covered with the naphthylene panels of the adjacent molecules. This packing structure is essentially the same as the one observed in a single crystal obtained from anthracene melt .…”

“…As shown in Figure b, the naphthylene panels were tilt‐aligned in a herringbone‐like motif, and the macrocyclic opening of one molecule was covered with the naphthylene panels of the adjacent molecules. This packing structure is essentially the same as the one observed in a single crystal obtained from anthracene melt . The voids in the packing were scarcely available, and their volume occupied 0.3% of the unit cell…”

Ring-Current Assessment of the Annulene-Within-an-Annulene Model for some Large Coupled Super-Ring Conjugated-Systems

“…Six of its bonds, which are all formally single and effectively carry zero ring-current, may be considered to form a part of both the inner ring and the outer ring. As can be seen from Figure 7, [6]cyclo-2,7-naphthylene (6) essentially consists (from a ring-current point of view) of six, completely isolated naphthalenic units, formed of two fused benzenoid rings (each bearing a ring current of intensity within 1 % of the benzene value), and a 30-membered inner-ring supporting (to three decimal-places) zero ring-current, according to a Single-Precision calcu Ring-current and bond-current maps for structure 6 (named [6]cyclo-2,7-naphthylene by Nakanishi et al 53 ). For conventions on the representation of ring currents (black) and bond currents -red, in the on-line version of the journalplease see the caption to [6]cyclo-2,7-naphthylene (6) is one of those structures for which a continuous spanningtree cannot be drawn; 1 accordingly, both the SinglePrecision and the Double-Precision calculations being discussed here were necessarily based on a branched spanning-tree.…”