18-Krone-6: Nur ein einfaches Molekül?

Abstract

The macrocyclic polyether 18-crown-6 is a potentially highly flexible molecule which can be regarded as a model substance for more complicated ionophores like Enniation B or even enzymes. In 54 crystal structure analyses 18-crown-6 adopts 12 different conformations. In these crystal structures 37 polyether crowns have approximate D_3d symmetry. To explore conformational space, random conformations with and without symmetry were generated. The energies of the best conformations lie within the range of the observed forms. To reproduce the conformational behaviour of 18-crown-6 in its complexes by force field calculations it is important to consider effects of solvation, charge distribution and directionality of hydrogen bonds. Because such effects are also important in computer-assisted molecular modelling and drug design, 18-crown- 6 can indeed serve as a model to develop better force fields.