Preferential solvation within hydrophilic nanocavities and its effect on the folding of cholate foldamers.
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.
Zhao
Yan
Y
Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, USA. zhaoy@iastate.edu
Zhong
Zhenqi
Z
Ryu
Eui-Hyun
EH
D020355:Cholates / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry
D020355:Cholates; D012997:Solvents; D014867:Water