IUCr Newsletter - Volume 24, Number 4 - 12
Crystal engineering, structural chemistry, function
Robert Kingsford-Adaboh (Ghana) described isolation, purification, synthesis, X-ray structure characterization, and biological testing of natural products having potential antimicrobial
and antioxidant properties. The talk was illustrated with unpleasant pictures of infected skin. Other talks in the session concerned Schiff Base complexes of transition metals (Aliou Barry,
Mauritania), quantum information processing with crystal engineering (Cornelius Fai, Cameroon), NMR studies of hybrid
nano materials (Dominic Schaniel, France), silver deficient coordination polymers hosting water in a one dimensional proton channel (Justin Nenwa, Cameroon), hybrid amino acids
and amines (Nourredine Benali-Cherif, Algeria), and features
of Rigaku's new XtaLAB Synergy (Tadeusz Skarzynski, Poland).
The final talk in the session by Christian Lehmann (Germany)
was a well illustrated summary of charge density studies and
their relationship to crystal engineering with specific focus on
halogen-halogen bonds and the photorefractive effect.
Crystal engineering, structural chemistry, function through design Chairs and Speakers.
Large facilities for emerging countries
Andrew Thompson (France) described the beamlines available for X-ray crystallographic studies at the French national
synchrotron facility (SOLEIL). Plans for an African Light Source
(AfLS) were described by Andreas Roodt (South Africa). Yvan
Georges Ngassa (France) described the use of precision electron
diffraction tomography and dynamic calculations to study cation distribution in spinels of importance to understanding their
chemical reactivity in the field of geoscience. Areej Abuhammad (Jordan) discussed important features of Jordan relevant to
its hosting a synchrotron facility (SESAME) that will serve the
countries of the middle east. In Jordan 50% of the population is
under 24, and 95% is under 55. Jordan's main industry is education (50% of that is medical education). Because Asia, Europe
and Africa are connected physically at Jordan and because people
from all countries of the world are welcome in Jordan it is an especially appropriate site for a synchrotron facility. Areej hopes
that the first protein structure completed in Jordan will come
from her lab. Florence Porcher (France) talked about neutron
diffraction projects and what constitutes a suitable neutron diffraction study. She presented a survey of all neutron Diffraction
Instruments and their distinguishing features.
In a closing plenary lecture, "What is a crystal?", Ron Lifschitz (Israel) discussed the evolution of the definition of a crystal from early definitions based on external appearance, surfaces
and geometric features, through definitions based on the composition of the building blocks internal to a crystal and the symmetry relationships relating those building blocks. This more
detailed definition arose when crystals were shown to diffract
X-rays and generate complex symmetric patterns. Diffraction
seemed to require long range order and certain types of symmetry that excluded 5-fold symmetry. When 5-fold symmetry was
detected in diffraction patterns the definition of a crystal had to
be further refined. The definition may continue to evolve. Fortunately, flawed definitions of what a crystal is did not prevent the
determination of hundreds of thousand of structures that have
improved the daily life of real (not theoretical) people over the
course of the past 100 years.
Participants at the First Pan-African Conference on Crystallography.
IUCr Newsletter ♦ Volume 24, Number 4 ♦ 2016