Symmetry and Molecular Chirality, Lord Kelvin's Legacy
by
Laurence Barron(Department of Chemistry, University of Glasgow)
→
Europe/Stockholm
Nordita
Nordita
Description
Chirality, meaning handedness, pervades much of modern science, from the
physics of elementary particles to the chemistry of life. To facilitate a
proper understanding of the structure and properties of chiral molecules
and of the factors involved in their synthesis and transformations,
this talk uses some principles of modern physics, especially fundamental
symmetry arguments, to provide a description of chirality deeper than
that usually encountered in the literature of stereochemistry. A central
result is that, although dissymmetry is sufficient to guarantee chirality
in a stationary object such as a finite helix, dissymmetric systems are
not necessarily chiral when motion is involved. The hallmark of genuine
chirality is that the two distinguishable mirror-image enantiomers cannot
be interconverted by time reversal T: the system breaks parity P but not
T and so exhibits a time-invariant enantiomorphism (the quintessential
chiral influence in atomic and molecular physics is the parity-violating
weak neutral current interaction, a time-even pseudoscalar). This removes
the confusion that has existed since Pasteur's time concerning the
nature of physical influences able to induce absolute enantioselection,
which is an important element in discussions of the origin of biological
homochirality.
