Molecular Dynamics Simulations of Alkylsilane Stationary Phase Order and Disorder. 2. Effects of Temperature and Chain Length

Published

December 1, 2005

Author(s)

Katrice A. Lippa, Lane C. Sander, Raymond D. Mountain

Abstract

In an effort to elucidate the molecular-level structural features that control shape-selective separations, we have investigated the molecular dynamics of chromatographic models that represent both monomeric and polymeric stationary phases with alkylsilane length and temperature conditions analogous to actual materials of low to high shape selectivity. The structural characterization of these models is consistent with previous experimental observations of alkyl chain order and disorder: alkyl chain order increases both with alkyl chain length and with reduced temperature. Models that represent shape-selective RPLC phases possess a significant region of distal-end chain order with primarily trans dihedral angle conformations; the extension of these ordered regions into the phase increases with an increase in chain length. Models with extended chain length (C30) possess a higher degree of conformational order, and are relatively insensitive to changes in surface coverage, bonding chemistry and temperature. Chromatography models of various chain length and over a temperature range that represent highly shape selectivity RPLC stationary phases all contain a series of well-defined and rigid cavities; the size and depth of these slots increase for the C30 models, which may promote the enhanced separations of larger size shape-constrained solutes, such as carotenoids.

Citation

Analytical Chemistry

Volume

77 No 24

Pub Type

Journals

Keywords

alkylsilanes, C18, C30, C8, carotenoids, molecular dynamic simulation, monomeric, polymeric, reversed-phase liquid chromatography

Citation

Lippa, K. , Sander, L. and Mountain, R. (2005), Molecular Dynamics Simulations of Alkylsilane Stationary Phase Order and Disorder. 2. Effects of Temperature and Chain Length, Analytical Chemistry (Accessed September 27, 2026)

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