Abstract |
Recently, some cyclopenta-fused polyaromatic hydrocarbons, an environmentally relevant subclass of chemicals, have been shown to have carcinogenic activity in animals. It has been suggested that benz(l)aceanthrylene (I), an active member of this subclass with a gulf region, has a trans dihydrodiol metabolite that is nonplanar and has two distinct spatial configurations. The authors have used MMP2(85) and AM1 to investigate the three-dimensional structure of the dihydrodiol and other similar derivatives of (I) and have found that although (I) is somewhat nonplanar the relevant derivatives are all nearly planar. Further, the authors have computed potential functions for the bending of the angular ring in the gulf region using MMP2(85), AM1, and ab initio computed energies for AM1 spatial configurartions and find that these molecules all have only a single potential minimum. The authors have performed the same calculations for benzo(c)phenanthrene and its 1,12 dimethyl derivative, molecules with a similar gulf region for which crystallographic data exists. In agreement with that data, the authors find that two distinct spatial configurations exist separated by significant barriers. The differences between the results generated by the three different methods of computation are discussed. (Copyright (c) 1992 John Wiley and Sons, Inc.) |