Enantiomeric separation of chiral ruthenium(II) complexes using capillary electrophoresis

Capillary zone electrophoresis (CZE) and micellar capillary electrophoresis (MCE) were applied for the enantiomeric separation of nine mononuclear tris(diimine)ruthenium(II) complexes as well as the separation of all stereoisomers of a dinuclear tris(diimine)ruthenium(II) complex. Nine cyclodextrin (CD) based chiral selectors were examined as run buffer additives to evaluate their effectiveness in the enantiomeric separation of tris(diimine)ruthenium(II) complexes. Seven showed enantioselectivity. Sulfated γ-cyclodextrin (SGC), with four baseline and three partial separations, was found to be the most useful chiral selector. In CZE mode, the derivatized γ-CDs were more effective than β-CDs while sulfated CDs work better than carboxymethyl CDs. In MCE mode, hydroxypropyl β-CD separated the greatest number of tris(diimine) ruthenium(II) complexes. The effects of chiral selector concentration, run buffer pH and concentration, the concentration ratio between chiral selector and other factors were investigated. Chirality, 2009. © 2008 Wiley-Liss, Inc.