title: Identification of isolated cavity features within molecular dynamics simulated chromatographic surfaces.
abstract: Highly ordered morphological features were characterized for molecular dynamics simulated alkyl-modified silica models that represent chromatographic materials with enhanced shape recognition capability. Deep cavities (8-10A wide) within the alkyl chains were identified for C18 polymeric models corresponding to shape-selective RPLC stationary phases. The all-trans conformational distal-end segments of these isolated cavities averaged over a 100 ps simulation time interval were observed to increase (up to 15 A) in models with an increase in both surface coverage and corresponding shape selectivity. Similar-structure cavities with significant alkyl chain ordered regions (>11A) were isolated from two independent C18 models (differing in bonding chemistry, density and temperature) that represent highly shape-selective materials. The size and depth of these ordered regions increased (up to 28 A) for the extended-length C30 alkyl phase models. These initial results offer a physical representation of alkyl-modified surfaces that may facilitate the identification of potential molecular features that may be involved in the shape-selective retentive processes, as well as illustrating the potential for such computational techniques to predict the molecular recognition capabilities of novel analyte-specific sorbents.
authors.affiliation: Analytical Chemistry Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA. katrice.lippa@nist.gov
authors.forename: Katrice A
authors.initials: KA
authors.lastname: Lippa
authors.forename: Lane C
authors.initials: LC
authors.lastname: Sander
mesh_terms: D000327:Adsorption; D002853:Chromatography, Liquid; D003198:Computer Simulation; D008958:Models, Molecular; D015394:Molecular Structure; D012821:Silanes / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D012821:Silanes