title: Structure and tunneling dynamics in a model system of peptide co-solvents: rotational spectroscopy of the 2,2,2-trifluoroethanol⋯water complex.
abstract: The hydrogen-bonding topology and tunneling dynamics of the binary adduct, 2,2,2-trifluoroethanol (TFE)⋯water, were investigated using chirped pulse and cavity based Fourier transform microwave spectroscopy with the aid of high level ab initio calculations. Rotational spectra of the most stable binary TFE⋯water conformer and five of its deuterium isotopologues were assigned. A strong preference for the insertion binding topology where water is inserted into the existing intramolecular hydrogen-bonded ring of TFE was observed. Tunneling splittings were detected in all of the measured rotational transitions of TFE⋯water. Based on the relative intensity of the two tunneling components and additional isotopic data, the splitting can be unambiguously attributed to the tunneling motion of the water subunit, i.e., the interchange of the bonded and nonbonded hydrogen atoms of water. The absence of any other splitting in the rotational transitions of all isotopologues observed indicates that the tunneling between g+ and g- TFE is quenched in the TFE⋯H2O complex.
authors: Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
authors: Javix
authors: J
authors: Thomas
authors: Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
authors: Yunjie
authors: Y
authors: Xu
mesh_terms: D006860:Hydrogen Bonding; D008872:Microwaves; D010455:Peptides / Q000737:chemistry*; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry*; D013057:Spectrum Analysis; D014270:Trifluoroethanol / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D010455:Peptides; D012997:Solvents; D014867:Water; D014270:Trifluoroethanol