tx034017h_si_015.pdb (0.92 kB)
Conformations of Benzene- and Dibenzo[a,l]pyrene Diol Epoxides Studied by Density Functional Theory: Ground States, Transition States, Dynamics, and Solvent Effects
dataset
posted on 2003-04-12, 00:00 authored by Kyung-Bin Cho, Kristian Dreij, Bengt Jernström, Astrid GräslundThe (−)-anti- and (+)-syn-diol epoxides of dibenzo[a,l]pyrene (DBPDE, 11,12-dihydroxy-13,14-epoxy-11,12,13,14-tetrahydrodibenzo[a,l]pyrene) and the stereochemically corresponding benzene diol epoxides (BDE, 1,2-dihydroxy-3,4-epoxy-1,2,3,4-tetrahydrobenzene) have been studied
by density functional theory (DFT) to determine the structures, energies, dynamics, thermal
properties, and solvent effects on the different conformers. The smaller BDE is used as a model
compound for studies of transitions between diequatorial and diaxial conformations of the
hydroxyl groups. It was found that DBPDE is distorted due to overcrowding in the fjord region
and that the arene oxide prefers to be on the same side of the saturated ring as the distal ring
(“in”) in most stereoisomeric states. For the anti-diastereomer, a diequatorial orientation of
the hydroxyl groups is preferred, while the orientation preference in the syn-diastereomer seems
to depend on the solvent and the in/out conformation. Transition states for the interconversions
between in and out conformations of DBPDE as well as between diequatorial and diaxial
conformations on BDE have been found, and transition rates have been estimated by transition
state theory. The barriers are found to be moderate, the highest being 9.6 kcal/mol. Solvent
effects as well as zero-point vibrational energy and thermal effects were included and found
to be significant in some cases. The results presented here are in agreement with previous
experimental studies.