A FAMILY OF SINGLE-ISOMER CHIRAL RESOLVING AGENTS FOR CAPILLARY ELECTROPHORESIS - 3 - HEPTAKIS(2,3-DIMETHYL-6-SULFATO)-BETA-CYCLODEXTRIN

The third member of a new family of single-isomer charged cyclodextrin s, the sodium salt of heptakis(2,3-dimethyl-6-sulfato)-beta-cycldextri n, has been synthesized, characterized, and used for the capillary ele ctrophoretic separation of the enantiomers of neutral, acidic, basic, and zwitterionic analytes. Though heptakis(2,3-dimethyl-6-sulfato)-bet a-cyclodextrin complexes much less strongly with any of the analytes t ested here than the preciously synthesized heptakis(2,3-diacetyl-6-sul fato)-beta-cyclodextrin and heptakis-6-sulfato-beta-cyclodextrin, it o ffers excellent enantioselectivities, complementary to those of the ot her two single-isomer, differently functionalized charged cyclodextrin s. Confirming the predictions of the charged resolving agent migration model, heptakis(2,3-dimethyl-6-sulfato)-beta-cyclodextrin allowed for the reversal of the migration order of the enantiomers of neutral ana lyses as the cyclodextrin concentration was increased. Just as with th e previous two single-isomer charged resolving agents, separation sele ctivity for the acidic, basic, and zwitterionic analytes could increas e, decrease, or pass a maximum as the cyclodextrin concentration was i ncreased, depending on the respective binding strength of the enantiom ers and the ionic mobilities of both the complexed and noncomplexed fo rms of the enantiomers.