Foldamer-Tuned Switching Kinetics and Metastability of [2]Rotaxanes
作者:Kang-Da Zhang、Xin Zhao、Gui-Tao Wang、Yi Liu、Ying Zhang、Hao-Jie Lu、Xi-Kui Jiang、Zhan-Ting Li
DOI:10.1002/anie.201104099
日期:2011.10.10
Slip sliding away: Foldamers (see picture, red) can function as modular stoppers to regulate the slippage and de‐slippage of pseudorotaxanes and the switching kinetics and metastability of bistablerotaxanes. By simply changing the solvent or the length of the hydrogen‐bonded foldamer, the lifetime of the metastable co‐conformation state can be increased dramatically, from several minutes to as long
One-pot, multi-molecular macrocyclization allows the highly selective preparation of strained macrocyclic hexamers stabilized by an inward-pointing continuous hydrogen-bonding network.
一锅法多分子大环化反应可以高度选择性地制备由向内连续氢键网络稳定的紧张大环六聚体。
Helical Organization in Foldable Aromatic Oligoamides by a Continuous Hydrogen-Bonding Network
Introduction of a continuous internal hydrogen-bonding network suppressed the conformational flexibility of a series of oligoaromatic foldamers; with a lengthened backbone. The helical ordering over up to six aromatic repeating units was established in solution by a 2D NOESY study and in the solid state by an X-ray diffraction method. Computational molecular modeling further corroborates the experimentally observed helical propagation in this class of foldable molecular strands.
Persistently Folded Circular Aromatic Amide Pentamers Containing Modularly Tunable Cation-Binding Cavities with High Ion Selectivity
In this work, we illustrated a novel design strategy that allows systematically tunable interior properties (effective cavity size, steric crowdedness, and hydrophobicity) contained within a novel class of shape-persistent aromatic pentamers to take place on a scale below 3 angstrom. Such finely tunable structural features are complimented by experimentally observable functional variations in ion-binding potential. Results of the selective, differential binding affinities of three circular pentamers for Li(+), Na(+), K(+), Rb(+), and Cs(+), substantiated by metal-containing crystal structures and computational modeling, are detailed.
Crystallographic Evidence of an Unusual, Pentagon-Shaped Folding Pattern in a Circular Aromatic Pentamer
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.