SC 99-23 Michael Meyer: Ab Initio Study of Flavonoids
Abstract: Flavone and the flavylium ion have been studied at Hartree-Fock,
Møller-Plesset and B3LYP hybrid density functional level to determine the structures
and barriers to internal rotation. Both molecules have a high perpendicular barrier
about the single bond connecting the phenyl ring with the benzopyrone and benzopyrylium
ring, respectively. In contrast to biphenyl both molecules have low coplanar barriers.
B3LYP overestimates the perpendicular barrier heights compared to other methods.
The dependence of the population and orbital energies on the torsion has been investigated
and the structures of both flavonoids have been estimated by means of a reaction
field model.
Keywords: flavonol,
conformation,
reaction field,
structure
CR: J.2
PACS: 87.15.Aa, 87.15.By, 31.15.Ar, 36.20.Ey