Crystallographic Evidence of an Unusual, Pentagon-Shaped Folding Pattern in a Circular Aromatic Pentamer
摘要:
Introduction of a continuous hydrogen-bonding network suppressed the conformational flexibility of an oligomeric backbone. Cyclization of a rigidified, suitably sized oligomer led to a circular aromatic pentamer. Its crystal structure determined by X-ray crystallography reveals a pseudo five-fold symmetric planarity in the solid state, which is quite unusual among all the previously described shape-persistent macrocycles and synthetic foldamers with biased conformations enforced by noncovalent forces.
One-pot, multi-molecular macrocyclization allows the highly selective preparation of strained macrocyclic hexamers stabilized by an inward-pointing continuous hydrogen-bonding network.