The First Pan-African Conference on Crystallography
Dschang, Cameroon, October 2016
The First Pan-African Conference on Crystallography (PCCr1) was held in Dschang, Cameroon, in October 2016 with the theme 'Crystallography for Sustainable Development in Africa'. The conference was organized by the Cameroonian Crystallography Association (CCrA), the Ministry of Higher Education of Cameroon, the U. of Dschang (UDs), the United Nations Educational, Scientific and Cultural Organization (UNESCO), the International Council for Science (ICSU) and the IUCr. PCCr1 is part of an IUCr effort to bring the science of crystallography to developing countries, where the powerful technique can contribute to sustaining the intellectual property rights, economic growth and human welfare of the country.
The program included round table discussions devoted to 'Crystallography as a vehicle to promote science in Africa and beyond' and 'Equipment for African laboratories and the African Light Source, AfLS'. The program included an exhibition of commercial instruments and innovative solutions from sponsors. An X2S Bruker single-crystal diffractometer, installed at the meeting site, will allow researchers from Cameroon and neighboring countries to conduct XRD single-crystal measurements during the months following the meeting. The meeting brought together researchers, students, government representatives and policy-makers from more than 35 countries. Patrice Kenfack Tsobnang, Valérie Richalet, the organizing team, all the partners, and sponsors are to be commended for creating an extraordinarily rich, educational, productive and rewarding event.
The opening ceremony included addresses by the Vice-chancellor of UDs, Claude Lecomte (IUCr Crystallography in Africa initiative) and representatives of sponsoring organizations. Gautam Desiraju, IUCr Past President, gave an opening keynote address entitled 'From molecule to crystal'. Summaries of the sessions covered in the meeting follow.William L. Duax
Crystal engineering and structural chemistry (function through design)
A session on supramolecular synthons and their influence on material properties began with a keynote lecture given by Alessia Bacchi (Italy) entitled 'Designing MOFs that breathe aromas'. A series of Metal Organic Frameworks (MOFs) containing decorated pyridyl ligands were used to selectively capture liquid active pharmaceutical ingredients (APIs) which have prominent aromas. Eugenol (oil of cloves), propofol (an anaesthetic) and carvacrol (the aroma of oregano) were stablized by interactions with host MOFs. Clement Tella (Nigeria) presented an overview of the use of mechanochemical methods to prepare co-crystals and complexes in bulk. If materials are to be used in large-scale devices it is imperative to develop methods to produce complexes on a larger scale than is possible from simple crystallisation. The reduction in solvent waste fulfills the need to do useful chemistry more efficiently and cost-effectively. Loïc Le Dréau presented the latest innovations in X-ray diffraction equipment, by highlighting developments made by Bruker AXS GmbH (Germany). Gift Mehlana (Zimbabwe) highlighted strategies for the design of porous materials for catalytic hydrogenation of carbon dioxide. The latter process is potentially of importance to Africa where increasing industrialization is beginning to have a significant impact on the levels of carbon dioxide and other pollutants in the atmosphere. Delia Haynes (South Africa) described the use of dithiadiazolyl radicals as building blocks for organic magnets. Dimerization of the radicals can be controlled using co-crystallization and inclusion in porous compounds enhances their properties. Materials of this type form topologically complex structures. Lars Öhrström (Sweden) spoke of the use of network topology analysis to provide insight into such structures. Jules Abodou Tenon (Côte d'Ivoire) and Claude Lecomte (France) brought the session to an end with two excellent talks describing the use of charge-density studies to give insight into spin-crossover complexes and other structures. The session gave a sense of work being done by and in collaboration with African scientists from across the continent. Much of the research presented touched on important aspects of science required for African development; from the production of novel materials for the beneficiation of natural resources to the remediation of pollution caused by industrial processes.Susan Bourne, Chair
Inorganic materials and industry minerals
The African continent is rich in raw materials critical to modern civilization, including minerals, metals, diamonds and phosphates. However, large parts of the value-added manufacturing chains for these materials are currently situated outside Africa. For a sustainable economic development of the continent, larger parts of these chains must be relocated to Africa, and the cross-border cooperation improved. This is where crystallography and the crystallographic community can be of help. This session combined many aspects of the study of structures, size effects, functionalities and applications of inorganic materials. The keynote lecture 'Ordered inorganic materials as templates for advanced functional nanostructures' delivered by Robert Mokaya (UK) revealed how to create new functional materials on the nanometre scale by manipulating suitable precursor structures. Michele Zema (Italy) described very intricate ordering phenomena in 'Coltan: a mineral family with unusual crystal chemistry'. Donald Tschuifon (Cameroon) described the 'Growth of ZnO nanotube arrays by hydrothermal methods on ZnO film-coated Si substrates'. Lahcen El Ammari (Morocco) gave a broad overview of the structures of phosphates and vanadates. Wulf Depmeier (Germany) reviewed the amusing scientific history of a potentially economically important Li mineral (jadarite) and then went on to describe the structure of denisovite: 'A fibrous, nano-crystalline, polytypic, disordered mineral', that he studied by electron crystallography and X-ray powder diffraction. Jérémie Muswema (DR Congo) discussed 'Gamma rays induced synthesis of supermagnetic Fe3O4 nanoparticles'. Márcia Carvalho de Abreu Fantini (Brazil), President of the Latin American Crystallography Association, described 'Mesoporous zirconia-based materials for catalysis and SOFCs'.Wulf Depmeier and Lahcen El Ammari, Co-chairs
Crystallography for life sciences
Co-chair Alejandro Buschiazzo (Uruguay) began the session on 'Crystallography for life sciences' with a comprehensive history of the field from Dorothy Hodgkin's insulin through viruses, with emphasis on molecular interactions dependent on sequence and fold and the evolution of conformational change in kinases. He noted that early ideas about one gene - one protein and one sequence - one structure were oversimplifications and that amyloids reveal that even a single sequence can have different 3D structures. Heini Dir (South Africa) described multifunctional superfamily of proteins as molecular machines and stressed how much can be learned by examining a structure under dozens of conditions. He discussed his determination of the first protein structure completed by an African Crystallographer. Elsie Yekwa (France) gave an excellent presentation of her studies of inhibitors of African arenavirus nucleases. She cloned, expressed and determined the structures of four proteins, and identified metal ions critical to the structure of a drug target. Co-chair Mino Caira (South Africa) described drug design using crystal structures of drugs and their protein targets. He discussed relative stabilities and solubility of polymorphs of a drug candidate and how to design drugs that are the most potent, selective and soluble. Cyclodextrins have been used to deliver drugs and hormones, including steroids, and Caira determined the structure of estradiol in a cyclodextrin. Bryan Sewell (South Africa) spoke of molecular evolution of amidases and industrial applications for nitrate production. One of his students from Kenya soaked 100 compounds into an amidase. His results raise questions about a popular theory about the design of antimalarial drugs. Eric Chabrière (France) has determined the structure of a thermo-stable protein from Vesuvio hot springs that has two catalytic activities and degrades insecticides and nerve gas. Details of the two mechanisms and the basis for stability revealed by X-ray analysis are being used to engineer more potent agents to decontaminate nerve gas and insecticides. Adewumi Adeyeye (South Africa) addressed tuberculosis resistance due to cell wall mycolic acid and structure determinations of proteins in the mycolic acid synthesis pathway. Richard Garratt (Brazil) discussed his studies of monomeric and polymeric human septin filaments that interact with the membrane and remodel it. The only reported crystal structure of a polymeric form is that of a hexamer composed of three types of monomers, but the active form seems be an octamer of the four putative different monomers. Garratt has found that homo dimers of one type seem critical to extended filament production.
Co-chair Suzanna Ward surveyed the size, growth and content of the Cambridge Structural Database (CSD). On the morning of 8 Oct 2016, it had 853,000 structures, has been growing by 60,000 per year and 1002 were added on its biggest day. Of these, 60% are metal-organic and 75% have aromatic rings. The top 200 pharmaceuticals are present and accounted for. Ward noted the existence of thorough reviews concerning the use of the data to understand the structural basis for the chemistry, properties and functional potential of molecules. She also described the predictive power of patterns derived from the data. CSD user Z. D. Yav (DR Congo) discussed selenium's potential as a hydrogen-bond acceptor based upon CSD data and ab initio calculations. Pinak Chakrabarti (India) has analyzed a pattern of specific NH-N interactions in adjacent peptides in the Protein Data Bank (PDB) and detected a secondary structure in which parallel β strands having these intramolecular NH-N interactions are linked together by intra β strand hydrogen bonds in a C5-fused ring motif that Chakrabarti terms topi. He suggests that topi may be conformational features as important as α helix and β strand and he finds them within 10 residues of ligand binding sites. Patrice Kenfack (Cameroon) describes a structure of a hydrated catananes having Co and Cr ions and a novel dodecameric water ring. Amy Sarjeant (USA) gave a clear, lively and entertaining presentation about some of the more unusual structures in the CSD. She was personally involved in solving the first neon-containing structure to the CCD. Only a few elements are not yet represented and radioactivity may prevent them from ever being crystallized. Matteo Leoni (Italy) described the content and use of the ICCD Powder Diffraction File, arguably the most powerful database available for comprehensive material identification. He also discussed the advances in Rietveld technique for detailed quantitative characterization of structure, microstructure and phase. Oliver Smarts (UK) reviewed enhancements of PDB programs for presentation and analysis of PDB structures. One useful feature was a simultaneous illustration of three types of protein representation (amino acid sequence, 3D ribbon drawing, and a map of α and β segments) on which the positions of individual amino acids can be highlighted. He also showed how CSD results could be used to improve resolution of small molecules in PDB structures.
Inorganic materials and mining
This topic was of immediate relevance to middle Africa at this time. The repair and replacement of the decomposing roads throughout the country could benefit from new technologies and materials that are becoming available but not widely or well known in most African Countries.
Co-chair Gilberto Artioli (Italy) reviewed traditional cement composition and production and discussed alternate materials that are more ecologically friendly (use less water to produce and release less CO2 upon decomposition). He contrasts the molecular and crystal structures of cement and new materials. He illustrated the value of using tomography to follow the nucleation of phases in cement. Herbert Poellmann (Germany) described new techniques to reduce CO2 in cement production and reviewed the structures, reactions and CO2 release properties of different components. Olonade Kolawole Adisa (Nigeria) forcefully asserted that world consumption of concrete and cement is second to water, that less than 40% of roads in Africa are paved and that Africa must use eco-friendly methods and materials and 'act local and think global' as it builds its roads. He advocated adoption of the methods and materials described by Poellmann. He listed impediments to a better life in Africa, ways to overcome those barriers, and quoted William Clinton, 'Advancing equal opportunity and economic empowerment is both morally right and good economics, because discrimination, poverty and ignorance restrict growth, while investments in education, infrastructure, scientific and technological research increase it, creating more good jobs and new wealth for all of us'. Sidoine Bonou (Benin) reported that because African women eat clays when pregnant, the composition and decomposition products of the clays are being analyzed by crystallographic techniques to detect potential toxins. The list of the dozens of compounds detected in powder diffraction patterns of fecal matter of clay eaters was stunning. Co-chair René Guinebretière (France) discussed phase transitions and strain in zirconium-containing industrial refractory blocks and learning more about material properties with the help of advances in techniques for gathering and interpreting reliable data. Roussin Lontio (Cameroon) discussed using metal oxide containing gas sensors to detect air pollution due to gases. He discussed different ways to prepare metal oxide sensors (hydrothermal, Sol-gel, electrochemical, precipitation etc.). His focus narrowed to Ni-Zn mixed-metal oxides as gas sensors with semiconductive properties. They have found increased conductance with increased Zn content in NiO. David Dodoo-Arhin (Ghana) described the electronic properties and potential use for solar energy generation and storage of newly synthesized copper oxide nanomaterials. The effect of high-energy milling, XRD, SEM, TEM, UV-Vis and FTIR were tested. Marielle Agbahoungbata (Benin) is studying TiO2 catalysts to combat waste water pollution, to purify water supplies and to improve catalytic properties with doping.
Crystal engineering, structural chemistry, function through design
Robert Kingsford-Adaboh (Ghana) described the 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.
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, which is of importance for 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 thousands of structures that have improved the daily life of real (not theoretical) people over the course of the past 100 years.William L. Duax
An African education
When elected President of the IUCr, I stated that I thought the future growth of crystallography would be in Asia, Latin America and Africa. I have attended 15 IUCr Congresses, 14 meetings of the Asian Crystallographic Association, 20 European Crystallographic Meetings, 45 meetings of the American Crystallographic Association, and dozens of other crystallographic meetings in countries that are members of the IUCr. I have witnessed the formation of the Latin American Crystallographic Association. As incredibly rewarding as these experiences have been, I have to say that the First Pan-African Crystallographic Meeting in Cameroon, Africa, in October 2016 was the most educational, exciting and enjoyable meeting of my life. I would like to describe some of my experiences in Cameroon.
After arriving in Cameroon, I collected my luggage and joined other crystallographers for a two hour shuttle ride on a road crowded with automobiles, trucks, motorcycles, and road construction vehicles. There were six or seven lanes to the road, all of which were under repair, and drivers were encouraged to drive in either direction in all seven lanes. The road had once been cement, but after years of heavy traffic, intense rain, and little or no maintenance it was now a dirt road with occasional huge chunks of cement here and there that drivers attempted to dodge by moving into other lanes. Each of four shuttles dropped its passengers at one of four hotels. Desk clerks took our passports in order to assign us rooms. We were told we should be in the lobby in the morning ready for a six hour bus ride to the meeting site, the U. of Dschang.
I started the next day by dropping my backpack onto my left foot smashing two toes. The pain was intense. I was able to read one email before losing Wi-Fi. I went to the lobby at 7:50 a.m. to find it empty. Everyone had been taken at 7:00 a.m. to another hotel for breakfast. I was taken to that hotel. There was chaos in the small lobby where the luggage of 100 crystallographers was piled in a huge heap. Porters were hauling the luggage to two buses that were parked in the street. The meeting staff were unrolling large banners proclaiming '1st Pan-African Crystallographic Conference' and taping them to the sides of the buses. We were advised to take water. I had no cash. A German theoretician gave me a 500 Whatzit coin (I never did learn the name of the currency). I got a big bottle of water and got 200 Whatzits in change.
We finally set out at 9:00 a.m. The road was the worst I had ever ridden upon in my life. Because of deep ruts and large pools of water of uncertain depth, vehicles drove not in the road but on either side of it. The constant jolting and jarring had my joints in rebellion with one another. After three hours we had a bathroom stop in a bucolic setting, surrounded by lush fields of coffee, banana, coconut, pineapple and palm plants. With so many plants it was hard to choose one to whiz upon. The men followed red dirt trails into the dense foliage. Women had a greater challenge. The tour guide said it was better to pee in the bush than in the shacks at the rest stops. He said that they were unsanitary. After three more hours on the bus we reached the university conference center and registered. We were taken to hotels to sort out the luggage and the Musée des Civilisations, a museum of Cameroonian history.
I had been aware that mankind 'came out of Africa' but the visit to the museum illustrated exactly how it happened. Although the museum included local artifacts from the Stone Age, the earliest people known to have inhabited what is now Cameroon were of the Sao civilization that came to the region in the sixth century BC. The museum presented the cultures of four or five kingdoms that evolved. Each kingdom had its own culture (polygamous or monogamous) and distinctly different life styles that persist to this day. The style of housing and roofs (pointed or flat, thatched, straw or wood) depended upon altitude (in the mountains or near the sea) and what building materials were near at hand. The cultures of the distinct kingdoms are present 2,500 years later. I had never appreciated the fact that the sexually explicit sculptures and carvings of early African tribes reveal an openness concerning the human body that was healthy and realistic. The visit to the museum was worth the trip to Cameroon.
One evening I had dinner at an all African table rather than an all white table. I talked with a sixth generation Cameroonian. He could trace his family back to one of the original kingdoms and described the form of polygamy that some of his ancestors practiced. Men of that kingdom could have just two wives and three houses. The man lived in a house with the sons of both wives and each wife lived in a different house with her daughters.
Over two thirds of the 400 attendees at the Congress came from 20 African nations. They were the most colorfully dressed collection of scientists I had ever seen in any of the countries I have been lucky enough to visit. They give new meaning to the phrase 'People of Color'. I began taking pictures of many the most colorfully dressed attendees. On the opening day, Francis Merlin Tchieno Melatagauia, the young man who ran the registration desk, wore the most amazing multi-colored, intricately patterned matching shirt and pants I had ever seen. I told him I wanted one like it. He sent for his tailor who took my measurements. I told Francis how much I was learning at the meeting and about my African-American son Stephen and my three grandsons. I told him that I would like my son and grandsons to visit their roots in Africa.
My hotel room had no internet, no hot water, no fresh towels, no shower curtain, a large barrel of fresh water, and an amazing collection of insects that were an entomologist's dream. It was wonderful. The conference center was appointed with a spacious auditorium and ample break time facilities. However the internet and PA system needed work. Talks were periodically interrupted by power failures. When the lights would come back on the projector would need to be restarted before the speaker could continue.
On the last morning of the meeting hot water miraculously arrived in my bathroom. But there was still no Wi-Fi and the local bank did not exchange dollars. After the closing session, another six hour bus ride with two bathroom stops, one bottle of pop and a bag lunch brought us to a bona fide Holiday Inn. The Holiday Inn had a life-sized statue of an Angel Gabriel out front, a life-sized portrait of the Sacred Heart of Jesus in the lobby and a crucifix over the door. A pile of 70 keys and 70 registration forms were on a table in a gazebo and we were instructed to take any one and register ourselves on the forms. The amenities of my room were no hot water, no drinking water, a broken air conditioner, and Wi-Fi that I could not connect to no matter how many passwords I was given by the desk clerk. But there was a working TV in my room that had eight religious stations in English. Guests are encouraged to pray for miracles (such as restoration of air conditioning) or offer the inconveniences up for the poor souls in purgatory. And I still had no local currency. I tried to go to bed but the room was stiflingly hot. I lay there sweating wondering what more can go wrong? How would I get to the airport? And would it cost money and not accept dollars? I assumed my most desperate and crazed countenance and begged Claude Lecomte to get me to the airport as soon as possible so I would be sure to catch my flight the next day. Claude calmed me down and assured me the bus would leave for the airport at 2:00 p.m. the next day. Since almost everything on the program had started late and taken two hours longer than estimated, I remained anxious. Unable to sleep I sat in the lobby writing my impressions of the Holiday Inn. There was a comforting smell of DDT in the insect free lobby. The computer in the lobby that guests are welcome to use was broken. It may soon be replaced with a picture of Saint Theresa the Little Flower. Someone came in to complain that there was no water in her room. Another complained she could not turn the air conditioning off in her room and she had frostbite. Areej Abuhammad of Jordan gave me 2000 Whatzits so that I could get another bottle of water.
On the the last morning I had an omelet for breakfast and took my antimalarial pill with a cup of hot tea. I used 1000 Whatzits and bought a bottle of water. The same bottle cost 300 Whatzits last week. The luggage was loaded and we boarded the bus. After 15 minutes of roasting in the sun we learned that the bus's battery was dead.
To pass the time I suggested that we sing songs from different countries. I explained that it was a crystallographic tradition to sing national songs at international meetings. The tradition had begun at NATO conferences in Erice, Italy. One of the organizers of the Erice Conferences, Lodovico Riva di Sanseverino, had collected the songs of over 50 nations into a song book. To get the ball rolling, I sang the bawdy English bar room ballad 'Her Mother Never Told Her'. This got laughter from those who understood English. I threatened to sing again unless someone else did. Mongi Debabbi from Tunisia sang an Italian song. The song had many verses and a simple chorus and soon everyone was singing along. Then Mongi's wife, Nina Elia Maria Cima, began to sing the Verdi 'Chorus of the Hebrew Slaves' from Nabucco and other Italians including Alessia Bacchi joined her. Elia sang the entire aria beautifully and received resounding applause. Then the Cameroonians stood and sang the National Anthem of Cameroon with their hands over their hearts. It was wonderful. Ludovico would have been pleased.
A 40 minute ride brought us to the base of Mount Cameroon and we climbed to observation shelters at the top overlooking the Atlantic. Then we were taken to the seashore where some people went into the water. One of them was Alwyn Bernard Dippenaar, a young protein crystallographer from South Africa that I had had dinner with on the first night. Before leaving the Holiday Inn we posed together with the Angel Gabriel.
Then we went to the Limbe Botanical Gardens (44 acres of preserved jungle). The guide took us through the medicinal garden, the banana garden, and the memorial to British soldiers who died in unspecified 'wars' that must have been uprisings that were put down by the British military. The botanical gardens were started when Germans began a rubber industry and set up a social club. After the Germans left, the British took over the port, the gardens and the Club. This began the anglophile era of Limbe and the introduction of Christianity. The club is now a restaurant called 'The Hot Spot'. The medicinal garden consisted of a diverse collection of trees including coffee, cinnamon, cocoa and rattan. We learned how chewing the barks and sucking the saps of specific trees cured specific illnesses. We were taken into the orchid greenhouse. It has probably been 20 years since an orchid has bloomed in the orchid house, but there are acres of beautiful flowers and trees in the pristine jungle surrounding it. Suddenly a downpour of rain began. It rains in Limbe every day all year round. We loaded the bus for the ride to the airport through the traffic jam/road construction/motorcycle clogged and cement dust filled air.
Months later a package with two Cameroonian outfits arrived in time for me to wear them at our family Christmas gathering and the annual musical review of the 130 year old Saturn Club of Buffalo. Since then a dozen friends from the Saturn Club and my sons and grand sons have ordered outfits and are now decked out in Cameroonian high fashion.William L. Duax