Analytical Sciences

Selectivity Enhancement for trans-2-(2,3-Anthracenedicarboximido)-cyclohexane-derived Diastereomers in HPLC by Using an Ordered Organic Stationary Phase

Atsuomi SHUNDO,* Megumi FUKUI,* Makoto TAKAFUJI,* Kazuaki AKASAKA,** Hiroshi OHRUI,** Dušan BEREK,*** and Hirotaka IHARA*

*Department of Applied Chemistry & Biochemistry, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
**Graduate School of Life Sciences, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba, Sendai 981-8555, Japan
***Laboratory of Liquid Chromatography, Polymer Institute of the Slovak Academy of Sciences, 842 36 Bratislava, Slovakia

2-(2,3-Anthracenedicarboximido)cyclohexane derivatives (AC) have been known as the evolutionary diastereomerizing reagents for enantiomer discrimination in HPLC with ODS. However, a substantial separation of diastereomers can be observed only at lower temperatures, such as -40°C. Therefore, in this work, poly(octadecyl acrylate)-grafted silica, ODA_n was applied as an alternative stationary phase to ODS for the separation of AC-derived diastereomers. As a result, complete separation was achieved even under the conventional condition: for example, methanol as the mobile phase and 0°C as the column temperature. An investigation on the temperature dependency of the selectivity demonstrated that ODA_n shows a remarkable increase in selectivity at temperatures below 30°C, which almost agreed with the peak-top temperature of the endothermic peak in a DSC thermogram for ODA₃₅ immersed in a mobile phase. The better separation would be derived from a highly ordered structure of ODA_n and a carbonyl-π interaction with AC-derived diastereomers.

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