Molecules, Crystals, and Chirality

Abstract

The development of the concept of chirality from the early work of Pasteur, van't Hoff and Le Bel to the work of Cahn, Ingold and Prelog is presented, and the constraints that chirality imposes on the symmetry of molecules - that chiral molecules may not possess an improper axis of rotation - is discussed. The relationship and differences between molecular symmetry and crystal symmetry, and the additional constraints imposed by the periodic nature of the crystal lattice are discussed, as are the symmetry elements introduced by the periodicity of the lattice - the glide plane and the screw axis. The constraints on the crystal lattice imposed by chirality of the molecular species in the lattice are also discussed. The methodology of single crystal x-ray structure analysis, including the application of anomalous scattering to the determination of absolute configuration, is briefly reviewed and the limitations on the information available from this most powerful of structure determination techniques is discussed.