4 the state of science in south africa
C H E M I S T R Y
4.4 Physical chemistry, includ- the first in the country to use this technique
ing polymer and theoretical for the determination of the crystal struc-
chemistry tures of compounds, but they were soon
followed by a number of younger academ-
ics at universities adopting this very impor-
A
physical chemist who was very influ-
ential at both experimental and the-
tant structural tool. Today at least six South
oretical levels was Victor Pretorius,
African universities have X-ray diffractom-
whose research in gas chromatography
eters as part of their research armory. De-
(GC) and mass spectrometry, together with
velopments in X-ray detector technology
that of the University of Pretoria’s Institute
and computing has meant that whereas it
of Chromatography (of which he was the
took several months at one stage to solve
a structure, this can now be achieved in a
director), resulted in many innovations and
matter of hours. The technique is the basic
improved detectors. In particular, the group
tool for crystal engineering or supramo-
was involved in the development of the
lecular chemistry, an area that is receiving
flame ionisation detector, turbulent flow
considerable attention world-wide.
chromatography, the theory of high-per-
formance liquid chromatography, and the
Significantly, one of the incumbents of the
initiation of a thorough study into the sol-
two DST/NRF national research chairs in
vent effect in GC-inlet techniques, which cul-
physical chemistry, namely Len Barbour at
minated in the development of the dynamic
the University of Stellenbosch, who has a
solvent effect inlet. Another earlier achieve-
chair in nanostructured functional materi-
ment by physical chemists that warrants
als, leads a group working in this area, es-
comment is that of the development by a
pecially in the study of the encapsulation of
Sasol team, in collaboration with a number
small compounds by noncovalent molecu-
of German chemists, of a modified catalyst
lar assemblies. This includes the sorption of
from local material for the Fischer-Tropsch
gases into lattice interstices as well as the
process, to be adopted in a new Sasol plant.
capture of substrates in large molecular
capsules or tubules assembled by means
Over the last 20 to 30 years, major contribu-
of hydrogen bonding or amphiphilic inter-
tions in physical chemistry have been made
actions. By exploiting such interactions in
in the areas of solution thermodynamics,
relatively simple polyhedral arrangements
kinetics and thermodynamics of solid-state
of molecules for instance, the group has
reactions, Raman spectroscopy in solid
assembled complex, multicomponent cap-
state chemistry, chemical kinetics, electro-
sules with internal volumes of up to 1300 Å
3
.
chemistry and X-ray crystallography.
A further programme involves the design
of highly porous materials with large lattice
X-ray crystallography has in fact long played voids by desolvating inclusion compounds.
a major role in the research activities of a Significantly, the group established that the
number of research groups in South Africa. low-density apohost phase of sublimed p-
Researchers at the NPRL were essentially tert-butylcalix[4]arene possesses zero-di-
116
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