Speaker
Jacky S Boudiombo
(Department of Chemistry, University of Cape Town, Private Bag, Rondebosch 7701, South Africa)
Description
Molecular selectivity by host-guest procedures is an increasing method to help in the separation of
enantiomers. In this study, two similar bile acids, cholic acid (CA) and deoxycholic acid (DCA), were
used as hosts to separate the mixtures of several isomer guests. The different compounds prepared
were analyzed by single crystal X-Ray diffraction. Our first guest mixtures were the isomers of
trimethoxybenzene (TMB) whose normal boiling points range from 241 to 255℃. We prepared
equimolar mixtures of the three isomers in pairs and dissolved the CA/DCA host in them, such that
the total guest to host ratio was 5. The selectivity preference is CA: TMB135 > TMB123 ≈ TMB124,
while it is reversed for DCA: TMB123 > TMB124 > TMB135. Some of the crystal structures with
CA as host suffered from partial disorder, while the DCA structures were grown from pairs of
equimolar guest mixtures, and all contained both guests in different proportions. Packing analysis
revealed the importance of layering of the hydrophilic and lipophilic regions of the structures with the
TMB guests accommodated in the lipophilic layers. Further analytical measurements carried out by
NMR are in agreement with the structural results.
Primary author
Jacky S Boudiombo
(Department of Chemistry, University of Cape Town, Private Bag, Rondebosch 7701, South Africa)
