Chiral separations of transition metal complexes using capillary zone electrophoresis

Several buffer additives that may facilitate chiral separation for opticall y active transition metal (TM) systems are investigated using capillary zon e electrophoresis. The TM complexes evaluated exhibit considerable heteroge neity with respect to total complex charge (0 to 4+), ligand type, and iden tity of the central metal including Ru2+, Ni2+, Cr3+, and Co3+. threo-D-s[]-Isocitrate, potassium antimonyl-d-tartrate and dibenzoyl-L-tartrate are i dentified as the most efficient chiral selectors. Interestingly, TM complex es exhibiting a (3+) total complex charge exhibit a reversal of enantiomer elution order versus all other complexes when separated using the tartrate additives. Operating parameters including pH, temperature, and capillary le ngth are discussed, and chiral separations of complex mixtures are demonstr ated. (C) 2001 Elsevier Science B.V. All rights reserved.