Zhao Yan, Zhong Zhenqi, Ryu Eui-Hyun
Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, USA.
J Am Chem Soc. 2007 Jan 10;129(1):218-25. doi: 10.1021/ja0671159.
The conformations of three cholate foldamers and one molecular basket were studied by fluorescence and NMR spectroscopy. In nonpolar solvents (e.g., hexane/ethyl acetate or ethyl acetate) mixed with a small amount of a polar solvent (e.g., alcohol or DMSO), the cholate oligomer folded into a helix with the hydrophilic faces of the cholates turned inward. Folding created a hydrophilic nanocavity preferentially solvated by the entrapped polar solvent concentrated from the bulk. This microphase separation of the polar solvent was critical to the folding process. Folding was favored by larger-sized polar solvent molecules, as fewer such molecules could occupy and solvate the nanocavity, thus requiring a smaller extent of phase separation during folding. Folding was also favored by smaller/acyclic nonpolar solvent molecules, probably because they could avoid contact with the OH/NH groups within the nanocavity better than larger/cyclic nonpolar solvent molecules.
通过荧光光谱和核磁共振光谱研究了三种胆酸盐折叠体和一种分子篮的构象。在与少量极性溶剂（如醇或二甲基亚砜）混合的非极性溶剂（如己烷/乙酸乙酯或乙酸乙酯）中，胆酸盐低聚物折叠成螺旋结构，胆酸盐的亲水面朝内。折叠形成了一个亲水性纳米腔，优先被从主体中浓缩出来的截留极性溶剂溶剂化。极性溶剂的这种微相分离对折叠过程至关重要。较大尺寸的极性溶剂分子有利于折叠，因为较少的此类分子能够占据并溶剂化纳米腔，因此在折叠过程中所需的相分离程度较小。较小/无环的非极性溶剂分子也有利于折叠，可能是因为它们比较大/环状的非极性溶剂分子能更好地避免与纳米腔内的OH/NH基团接触。
