title: Structure and Dynamics of Water/Methanol Mixtures at Hydroxylated Silica Interfaces Relevant to Chromatography.
abstract: The spectroscopy and dynamics of water/methanol (MeOH) mixtures at hydroxylated silica surfaces is investigated from atomistic simulations. The particular focus is on how the structural dynamics of MeOH changes when comparing surface-bound and MeOH in the bulk. From analyzing the frequency frequency correlation functions it is found that the dynamics on the picosecond time scale differs by almost a factor of two. While the relaxation time is 2.0 ps for MeOH in the bulk solvent it is considerably slowed-down to 3.5 ps for surface-bound MeOH. Surface-adsorbed MeOH molecules reside there for several nanoseconds and their H-bonds are strongly oriented towards the surface-OH groups. These results are of particular relevance for chromatographic systems where the solvent may play a central role in their function. The present simulations suggest that surface-sensitive spectroscopic techniques should be useful in better characterizing such heterogeneous systems and provide detailed insight into solvent dynamics and structure relevant in chromatographic applications.
authors.affiliation: Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056, Basel, Switzerland.|Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, Universitätsstraße 150, D-44801, Bochum, Germany.
authors.forename: Prashant Kumar
authors.initials: PK
authors.lastname: Gupta
authors.affiliation: Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056, Basel, Switzerland. m.meuwly@unibas.ch.
authors.forename: Markus
authors.initials: M
authors.lastname: Meuwly
keywords: chromatography; infrared spectroscopy; molecular dynamics; silica; two-dimensional spectroscopy