Structure and Dynamics of Chiral Molecules

Could there be chiral methane? What is the characteristic structural feature (in a physicochemical sense) of a molecule? This question dates back to Louis Pasteur, the discoverer of molecular chirality, and since the work of van't Hoff and Le Bel is generally considered by chemists as solved. In the present article it is pointed out that there exist fundamentally conflicting theoretical views of the physical origin of molecular chirality. These views predict consequences that could, in principle, be distinguished experimentally, but at present there is no conclusive experimental evidence available. Possible experiments are suggested that test different hypotheses. The importance of the magnitude of the parity-violating energy difference δE_PV in molecules due to the weak nuclear force for both the structure and spectra of chiral molecules and for the kinetics of racemization is discussed. The chemical relaxation rate coefficient of chiral molecules with some appreciable energy of excitation is derived for several limiting cases of a simple statistical mechanical model, which takes ΔE_PV into account.