Probing the organization of liquids using 129Xe NMR spectroscopy III: Linear hydrogenated and fluorinated alcohols

• The liquid structure of hydrogenated and fluorinated alcohols was studied with Xenon NMR . • Temperature dependent spectra allow comparisons at similar thermodynamic conditions. • Molecular dynamics simulations confirm and complement the NMR results. • Xenon atoms are preferentially located near aliphatic ends (CH3, CF3), avoiding CH2OH groups. • The advantages of using xenon as an NMR probe are clearly demonstrated. The liquid organization of six alcohols (CH 3 (CH 2 ) n OH, n = 1, 2, 3, 5, 7, 9) and five fluorinated alcohols (CF 3 (CF 2 ) n CH 2 OH, n = 1, 2, 3, 4, 5) was studied using 129 Xe as an NMR probe. For the first time, spectra were obtained as a function of temperature to allow the comparison of the different solvents at similar thermodynamic conditions. Correlations of the xenon medium shifts as a function of group density were obtained, assessing the relative interactivity of the different groups forming the solvent molecules. Molecular dynamics simulations confirm and complement the molecular interpretations obtained from the NMR results. It is shown that xenon is not randomly distributed throughout the liquid, but preferentially located near the aliphatic end of the solvent molecules, resulting in an enrichment of CH 3 and CF 3 groups around xenon. Conversely, xenon’s coordination sphere is depleted in CH 2 OH groups relatively to the stoichiometric proportion. This work extends to n -alkanols and 1H,1H-perfluoroalkanols the methodology previously applied to n -alkanes, perfluoroalkanes and perfluoroalkylalkanes, allowing the prediction of the 129 Xe medium shift in all these solvents, at any temperature, providing the density is known. The advantages of using xenon as an NMR probe are clearly demonstrated. The high sensitivity of the xenon atom provides detailed information on the nature, density and organization of the solvent’s chemical groups within its coordination sphere.