Molecular Polka: Complex rotations of small molecular rotors in material and biological systems.

Jerome Baudry, Chemical Sciences, University of Illinois at Urbana-Champaign

Rotational properties of small (methyl-sized) molecular rotors have functional consequences that span many energetic-, size- and time- scales in chemical and biological systems. The rotation of these rotors is very sensitive to environmental conditions such as molecular packing, temperature and structure; thus making these many small and relatively simple molecular groups behave in a complex fashion. New experimental and theoretical results show that the rotation of small molecular rotors can be catalyzed by van der Waals interactions, thus making very rigid rotators become thermally activated at room temperature. These environment-catalyzed rotations of functional groups can occur in solid phase and in native biological structures. The relevance of this catalytic effect is discussed in terms of natural occurrence and possible contribution to the structural and functional properties of large-scale molecular systems such as crystals and proteins.