Molecular theory of selectivity based on solute structure for nematic liquid-crystalline phases in gas—liquid chromatography

✍ Scribed by Daniel E. Martire

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 965 KB
• Volume: 406
• Category: Article
• ISSN: 1873-3778
• DOI: 10.1016/s0021-9673(00)94015-9

✦ Synopsis

A molecular theory, based on a lattice model, is presented. The theory addresses the enhancement in selectivity experienced by structural isomers (solute components) from the orientational order of nematic phases (solvent components) in gas-liquid chromatography. A variety of molecular structures of solutes are treated in the context of the model: thin and thick rods, plates, cubes, and semiflexible chains. Representative solvent molecules, mimicking low-and high-temperature nematogens, are considered. Each consists of a rigid, rodlike core and, in general, semiflexible pendant groups. Selectivity enhancements are determined relative to the bulky cubic solutes for model isomers having the same reduced molecular volume, c2. The results are discussed in terms of the calculated orientational order of the solute molecules and other molecular-level effects. It is seen that the selectivity enhancement for a conformationally rigid isomer increases as its molecular-structural indicator, g2 = 3(& -q2), decreases, where & is its reduced molecular area.