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MolArch+ Movies 6

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MOLecular ARCHitecture+ - MolArch+ Movies
This page gives an overview on different types of molecular animations that were generated using the MolArch+ program. Racemization of [8]Helicene	Racemization of [8]Helicene
Racemization of [8]Helicene
Helicenes are benzologues of phenanthrene. With four or more rings (tetrahelicene, or [4]helicene) the compounds exist in two helical, enantiomeric forms, with C2 symmetry. Racemization experiments, carried out in the seventies, gave surprising results: not only did racemization occur at lower temperatures than expected from hardware models; the barriers even showed a tendency to level off for a higher number of rings. Calculations confirmed that for [4]- to [9]helicene the racemization occurs via a CS symmetric transition state (TS). For [8]helicene shown in the animations on the left, the energy barrier to racemization was measured as well as calculated to amount to about 175kJ/mol. Data and transition state structures were taken from http://www.cmbi.kun.nl/~borkent/motm/deca.html. For details see also R. H. Janke, G. Haufe, E.-U. Würthwein, and J. H. Borkent, J. Amer. Chem. Soc. 1996, 118, 6031; and S. Grimme and S. D. Peyerimhoff, Chem. Phys. 1996, 204, 411. Ball-and-Stick Models CPK Models MPEG MPEG MPEG MPEG MPEG MPEG Ribbon Models Surface Models MPEG MPEG MPEG MPEG MPEG MPEG