2013 Nobel Prize in Chemistry

The 2013 Nobel Prize in Chemistry was awarded today to Martin Karplus (Universite de Strasbourg & Harvard University), Michael Levitt (Standford) and Ariel Warshel (University of Southern California) for:

“for the development of multiscale models for complex chemical systems”

I am a little sheepish to admit how little I actually know about computational chemistry and the theory behind it.  Karplus, however, is very familiar to me (and spectroscopists everywhere!) for development of the Karplus equation:

This equation equates the magnitude of vicinal 3JH-H coupling constants and the dihedral torsion angle (Φ)!  What does this mean?  By correctly assigning and calculating these coupling constants you can get conformational information about your molecule!  Pretty incredible discovery there – the coupling constant can be used to give information, not only of connectivity, but also local geometries.  This can be particularly helpful in understanding complex organic molecules.  The relationship is limited to unstrained hydrocarbons and may not be an accurate representation of ring constrained systems but is still widely used evewhere!