The Photochemical <i>cis–trans</i> Isomerization of Free Stilbene Molecules Follows a Hula‐Twist Pathway

Abstract

A motion breaking with tradition: The cis–trans isomerization of nonpolar conjugated π systems does not proceed simply by the 180° twist of a CC bond (“one-bond flip”, OBF), but by the rotation of a central CH group out of the plane (“hula twist”, HT). The hula-twist motion does not require any external constraint but is driven by an internal force: the slope on the way through a conical intersection. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2004/z54221_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.