Search results for "Solvent dynamics"
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Solid-state NMR and computational investigation of solvent molecule arrangement and dynamics in isostructural solvates of droperidol.
2015
(13)C, (15)N and (2)H solid-state NMR spectroscopy have been used to rationalize arrangement and dynamics of solvent molecules in a set of isostructural solvates of droperidol. The solvent molecules are determined to be dynamically disordered in the methanol and ethanol solvates, while they are ordered in the acetonitrile and nitromethane solvates. (2)H NMR spectra of deuterium-labelled samples allowed the characterization of the solvent molecule dynamics in the alcohol solvates and the non-stoichiometric hydrate. The likely motion of the alcohol molecules is rapid libration within a site, plus occasional exchange into an equivalent site related by the inversion symmetry, while the water mo…
Does glycosyl transfer involve an oxacarbenium intermediate? Computational simulation of the lifetime of the methoxymethyl cation in water
2011
2D free-energy surfaces for transfer of the methoxymethyl cation between two water molecules are constructed from molecular dynamics (MD) simulations in which these atoms are treated quantum-mechanically within a box of 1030 classical solvent water molecules at 300 K. This provides a simple model for glycosyl transfer in water. The AM1/TIP3P surfaces with 2D-spline corrections at either MPWB1K/6-31+G(d,p) or MP2/6-31+G(d,p) contain a shallow free-energy well corresponding to an oxacarbenium ion intermediate in a DN*AN mechanism. MD analysis at three temperatures leads to a classical estimate of the lifetime of the methoxymethyl cation in water; when quantum corrections for vibrational zero-…