Spotlight: Bob Compton
CHIRALITY ON EARTH AND IN THE UNIVERSE
The word chiral comes from the Greek word for hand (χειρ). A chiral object cannot be superimposed upon its mirror image. Because your hand has a top and bottom (three dimensional) you cannot superimpose your right and left hand, thus chiral objects possess a “handedness.” The great French scientist, Luis Pasteur, discovered that many molecules are chiral and further discovered that the specific chirality of a molecule can determine its biological effectiveness. A chiral molecule is described by its absolute configuration (position of the atoms in the molecule, R, S) or the direction of rotation of linear polarized light (l or d, + or -) upon passing through it. Each is called an enantiomer. The handedness often determines the taste or smell of the molecule, e.g. (+)-limonene is found in orange and (–)-limonene is found in lemons; (+)-Carvone has the odor of caraway seed while (-)-Carvone has the odor of spearmint. Pure enantiomers are extremely important in the drug industry, usually one enantiomer is effective while the other may be ineffective or poisonous. Chirality is also seen in climbing plants as most are found to twine to the right (Jasmine, Mandevilla, Eucalyptus tree,…) and to a lesser extent to the left (honeysuckle…). Chirality is a fact of life as well, the amino acids supporting life are almost exclusively “left” handed! The weak force in nature also has a handedness, the free neutron decays into a proton, antineutrino and a left-handed spinning electron. Finally, as a result of the expanding universe, many of the billions of spiral galaxies are also chiral. This presentation will discuss physics, chemistry and biology of chirality in nature on a level understandable by any student or adult.
Compton’s family moved to Oak Ridge in 1943 so that his father could take a job at Y-12 during the Manhattan Project. Compton has a PhD in physics and worked at ORNL until his retirement as a Senior Corporate Fellow in 1996. He then worked as a professor of physics and chemistry at the University of Tennessee until his retirement in 2015.
Spotlights are included with museum admission.