Principles of Chiral Separations by Free-Solution Electrophoresis - Chiral Separations by Capillary Electrophoresis - page 43

very nature. It is well-founded to expect that the life science research will ask for
the solution of novel and more demanding tasks that either result from or are con-
nected with chirality. This is the main reason why to deepen the understanding of
the interactions between chiral selectors and chiral analytes and why to enlarge the
set of accessible chiral selectors. The necessity of the deeper understanding of chiral
separations is emphasized by the fact that analogy and personal experience are more
effective in the a priori estimation of the promising selectors and, sometimes, even in
the proposing chiral separations than the existing theories. Life science research will
require the investigation of compounds and compound types that are practically out
of attention of the present chiral separation science. An example may be the family
of more than 50,000 fully synthetic cluster compounds of boron. The compounds
are based on the three-center two-electron chemical bond, which does not exist in
the compounds occurring in nature, see, e.g., Ref. [37]. The accumulation of these
bonds substantially contributes to unusual chemical properties of the cluster com-
pounds of boron and to their capability to provoke remarkable biochemical effects.
This capability is demonstrated by the recently discovered potential of some cluster
compounds of boron to treat the HIV forms resistant to organic compounds [38]. The
majority of the boron compounds are structurally chiral due to the rigidity of their
three-dimensional clusters. These electron dei cient compounds represent a great
challenge for the development of chiral selectors free of spontaneous racemization
and featured by chiral discrimination capabilities different from those of the existing
chiral selectors.

LIST OF SYMBOLS
μ A,eff

effective mobility of the species A

μ A, i ionic mobility of the i th form of the species A

x A, i molar fraction of the i th form of the species A

μ RA,eff effective mobility of the enantiomer ( R )A

μ RA ionic mobility of the enantiomer ( R )A

x RA molar fraction of the enantiomer ( R )A

μ RAC ionic mobility of the complex ( R )AC

x RAC molar fraction of the complex ( R )AC

K RA stoichiometric stability constant for the reversible complexation of the

enantiomer ( R )A with the chiral selector C

[( R ) AC ] equilibrium concentration of the complex ( R )AC

[( R ) A ] equilibrium concentration of the enantiomer ( R )A

[ C ] equilibrium concentration of the chiral selector C

μ SAC ionic mobility of the complex ( S )AC

K SA stoichiometric stability constant for the reversible complexation of the

enantiomer ( S )A with the chiral selector C

μ SA,eff effective mobility of the enantiomer ( S )A

Δμ eff difference of the effective mobilities of the enantiomers ( R )A and ( S )A

S separation selectivity

v A,app apparent migration velocity of the analyte A, identical with its velocity

toward the separation capillary wall