Cover Picture: Lock-and-Key Principle on a Microscopic Scale: The Case of the Propylene Oxide⋅⋅⋅Ethanol Complex (Angew. Chem. Int. Ed. 13/2007)



The lock-and-key principle is illustrated on a microscopic scale by the binding between propylene oxide (PO) and ethanol. PO acts as a rigid ‘lock’ and EtOH offers keys in the form of the gauche−, gauche+, and trans conformers. In their Communication on page 2276 ff., N. Borho and Y. Xu use rotational spectroscopy and ab initio calculations to analyze the six possible hydrogen-bonded conformers (three of which are shown in the cover picture) of the 1:1 PO⋅⋅⋅EtOH molecular complex.