Solvent effects on the screening of parallel combinatorial libraries for selectors for chiral chromatography

The correlation between the resin-swelling property and the outcome of the crucial equilibration assay used in our parallel library screening method is investigated. It is found that the incorporation of CHCl3 (an effective swelling solvent for both the polystyrene and TentaGel resins) into the equilibration solvent leads to faster equilibration and thus shorter library screening time. The outcome of the equilibration experiment is also found to depend on the chemical nature of the solid base resins. It appears that polystyrene resin, which has a relatively inert surface, provides higher enantioselectivity than the polar TentaGel resin. The importance of a thoroughly swelled resin for the direct assay of functional groups on the resin is demonstrated.