Geodesic polyarene

Crystal structure of pentaindenocorannulene.

A geodesic polyarene in organic chemistry is a polycyclic aromatic hydrocarbon with curved convex or concave surfaces.[1] Examples are fullerenes, nanotubes, corannulenes, helicenes and sumanene. The molecular orbitals of the carbon atoms in these systems are to some extent pyramidalized resulting a different pi electron density on either side of the molecule with consequences for activity.

One member of this group of organic compounds, pentaindenocorannulene (depicted below),[2][3] can be considered a large fullerene fragment. The experimentally obtained curvature and degree of pyramidalizion (12.6° [4]) are both actually larger than that of fullerene but according to its discoverers the compound is relatively easy to synthesize starting from corannulene and a way is opened to produce larger such fragments by stitching.

Some bowl-shaped molecules reported in the literature are in fact partially hydrogenated. A C56H40 hydrocarbon has been synthesized containing 54 of the 60 carbon atoms found in fullerene [5]

See also

References

  1. ↑ Geodesic polyarenes with exposed concave surfaces Lawrence T. Scott,† Hindy E. Bronstein, Dorin V. Preda, Ronald B. M. Ansems, Matthew S. Bratcher and Stefan Hagen Pure & Appl. Chem., Vol. 71, No. 2, pp. 209–219, 1999 Link
  2. ↑ Pentaindenocorannulene and Tetraindenocorannulene: New Aromatic Hydrocarbon Systems with Curvatures Surpassing That of C60Edward A. Jackson, Brian D. Steinberg, Mihail Bancu, Atsushi Wakamiya, and Lawrence T. Scott J. Am. Chem. Soc.; 2007; 129(3) pp 484 - 485; (Communication) doi:10.1021/ja067487h
  3. ↑ The two steps in this sequence are a Suzuki-Miyaura coupling with an ionic liquid and Tris(dibenzylideneacetone)dipalladium(0) and a Heck reaction with another palladium catalyst, DBU and DMAC
  4. ↑ by a so-called p-orbital axis vector (POAV). The value for fullerene is 11.6° and benzene 0°
  5. ↑ Synthesis of a C56H40 Hydrocarbon Bearing a 54-Carbon Framework of C60 Kung K. Wang, Yu-Hsuan Wang, Hua Yang, Novruz G. Akhmedov, and Jeffrey L. Petersen Org. Lett., 2009 doi:10.1021/ol900749a
This article is issued from Wikipedia - version of the Sunday, October 19, 2014. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.