Crystallography in Singapore

An overview

Swami begins with his experience when he decided to move to Singapore. “In 1998, the most important doubt for my then 8 year old son was whether pizza would be available there. With my knowledge of geography and his level of comprehension I convinced him that Singapore is just an extension of California but there is a big ocean in-between. I even managed to make him believe that there would be bus service between Singapore and Los Angeles. After moving to Singapore I learned very soon that the kids of my ‘expat’ (a term we use here for foreign workers) colleagues had similar doubts about burritos, sushi, masala dosa and so on”.

Singapore is a small island of about 690 sq. km with a population of ~4 million people. It is essentially a city country with no natural resources, but this has not hampered the country’s growth since its independence from Malaysia in 1965. Within a short span of time Singapore has become a highly developed country with a successful free market economy. Until the beginning of the 1990s Singapore was known mostly for economical shopping. Recently, it has become a choice destination for scientists, especially crystallographers as can be seen from the increase in the number of crystallographers and research areas over the past 10 years.

“Crystallography is very new to Singapore”, according to Lip Lin Koh who returned to Singapore in 1964 from Boston University. He was not aware of any crystallographic research or teaching in Singapore or Malaysia at that time. All three universities (U of Malaya at Kuala Lumpur, U of Malaya at Singapore and Nanyang University, Singapore) had Physics and Chemistry departments, but crystallography was not part of the curriculum. He was the first to introduce crystallography as part of Physical Chemistry. In the mid 1970’s, he was able to obtain a table-top X-ray unit, a Weissenburg camera and a Debye-Scherr camera. These were mainly used for demonstration and simple experiments and projects for senior undergraduate students. The first crystal structure publication from Singapore was: Thianthrene gold (III) chloride (chloroform solvate) at -70 ºC. N.W. Alcock, K.P. Ang, K.F. Mok, and S.F. Tan. Acta Cryst., B34, 3364 (1978). K.P. Ang was a former head of the chemistry department, National University of Singapore (NUS) and S.F. Tan was an emeritus professor in the same department.

It was only in October 1989 that the first single crystal X-ray diffractometer (a Siemens P3) with a MicroVax computer arrived at the Department of Chemistry, NUS. Koh says, “It was with this instrument that I was able to become a crystallographer again, picking up my skills after 20 years! Luckily, I still remembered my crystallography, thanks to the physical chemistry that I had been teaching and my sabbatical leave in 1987”. The first researchers to actually use the diffractometer were: K.F. Mok (after retirement he moved to Nanyang Technological University (NTU)), and W.L. Kwik (deceased), followed by Y. Lam andY. Xu (Koh’s postdoc from 1992 to 1995). Xu left for the National Institute of Education (NIE) in 1996 to start her own X-ray crystallography lab equipped with a P4 diffractometer. The current service facility at the Department of Chemistry, NUS was established in 1997 when the first Siemens SMART 1000 CCD diffractometer arrived, and Jagadese J. Vittal, an experienced chemical crystallographer from Canada, joined the faculty. Now more than 20 faculty members from the department of chemistry and their research groups routinely use this facility.

Geok Kheng Tan, who maintained the P3 in the earlier days, is now taking care of four diffractometers. She is likely to hold a record for collecting and solving at least 5000 newly synthesized small molecule structures in Singapore. After training in Germany and Japan, George Tang (now General Manager, Bruker, Singapore) returned to Singapore as a salesman for Siemens and sold the first diffractometer in Singapore. He also confirms that an old Siemens powder XRD system was installed in Robertson Research, a commercial geological lab, in 1989.

Macromolecular crystallography in Singapore started in 1997 after Prasanna Kolatkar arrived. Also Nam-Hai Chua, one of the founding professors of the Institute of Molecular and Cell Biology (IMCB, 1987) established the Institute of Molecular Agrobiology in 1995 (now called Temasek Lifescience Laboratories, TLL) and recruited some of the early birds in 1998. Subsequently, the Singapore government has undertaken a strong commitment to promote Singapore as a biotechnology power-house in this region. Through the National Science and Technology Board, which is now known as the Agency for Science, Technology and Research (A*STAR), the government has established more research institutes. In addition, NTU established its School of Biological Sciences and recruited several crystallographers. In summary, the two universities, NUS and NTU (with their appropriate departments or schools), and several research institutes, like IMCB, Genome Institute of Singapore (GIS) and TLL, are now very actively involved in macromolecular crystallographic research.

Chemical crystallography

Edward R.T. Tiekink had a brief stint at NUS (2001-04) before joining the University of Texas at San Antonio in the Fall of 2005. While at NUS his research interests revolved around chemical crystallography with an emphasis on main group element chemistry, the development of metal-based drugs for the treatment of cancer, rheumatoid arthritis and tropical diseases and new molecular materials. His work on steric control of supramolecular aggregation is nicely illustrated in a series of three binary zinc xanthate structures as shown in Fig. 2.1.

Jagadese J. Vittal confessed that he was really afraid of symmetry and space groups when he was a graduate student. During his postdoc at the University of Western Ontario he was encouraged to take the crystallographic course offered in the Chemistry Department. He fondly recalls that his mentor in crystallography, Nicholas Payne, “was a dedicated crystallographer who really enjoyed teaching crystallography. He patiently taught me to be a well-rounded crystallographer”. Later Vittal was a service crystallographer in the same department before he accepted a position at NUS in 1997. The Siemens CCD diffractometer, installed in the Department of Chemistry at NUS in 1997 was not only the first one in Singapore but also in that region and it was one of the reasons Vittal moved to Singapore.

Being a crystallographer by profession and synthetic inorganic chemist by training, he initiated a research program in crystal engineering and chemistry of metal thiocarboxylates. His experience in crystallography helped him to venture into nanocrystals. He is currently interested in the supramolecular transformation of structures, aligning double bonds in coordination polymers in the solidstate and water clusters. The structure of water chains hosted by an inorganic crystal lattice from his work is illustrated Fig. 2.2.

Yulin Lam, from the Department of Chemistry, NUS, is one of a very few Singaporeans trained and currently practicing chemical crystallography in Singapore. She received her PhD from NUS (Supervisor: Hsing Hua Huang) in the area of conformational analysis. She was a Research Fellow at the Scripps Research Institute and the Institute of Molecular and Cell Biology in Singapore before joining NUS. Her research interest includes combinatorial chemistry, structure-based and pharmacophore-based drug design and conformational analysis.

Siau Gek Ang is one of the chemistry faculty members who is interested in the application of spectroscopic techniques and X-ray diffraction methods. Her research interests include bioactive compounds from Chinese herbs and the organometallic chemistry of osmium and ruthenium. Currently she is Registrar of NUS.

Weng Kee Leong is using single crystal X-ray crystallographic techniques to elucidate the solid-state structures of newly synthesized heteronuclear and intermetallic clusters, nanomaterials and heterogeneous, and homogeneous catalysts.

Feng Xu, a new member of the chemistry faculty of NUS, is interested in both chemical crystallography and macromolecular chemistry. He learned chemical crystallography as a graduate student in the Chinese University of Hong Kong under Tomas C.W. Mak. He worked in macromolecular crystallography at the Wistar Institute, Philadelphia, USA before coming to Singapore in 2005. He is interested in supramolecular chemistry and crystal engineering of hydrogen-bonded molecular solids; design and control of molecular assemblies and packing arrangements to generate crystals with specific properties as new materials and drugs; structural biology of viruses by X-ray crystallography; molecular modeling and electron microscopy;and understanding protein structure and its biological function for pharmaceutical application.

Tim White is at the School of Materials and Engineering, NTU. He is interested in crystallographic investigations of functional ceramics using electrons, X-rays and neutrons, especially materials related to environmental remediation and catalysis. His structure of triclinic Ca₁₀(AsO₄)₆F₂ svabite is shown here (Fig. 2.3). He received his PhD from the Australian National University and has had postdoctoral research experience in practically every capital city in Australia, the USA, Germany and Japan. He has been in Singapore for more than a decade beginning with the establishment of the Environmental Technology Institute in 1996. Presently, he is the Director of the Facility for Analysis, Characterization, Testing and Simulation (FACTS) which is the largest multipurpose electron microscopy and X-ray diffraction laboratory serving the crystallographic community in Singapore.Tim says, “Singapore is an unusual, and possibly unique country, in which to build a research group. The support for research is tremendous, but an appreciation of the utility of fundamental scientific investigations such as crystallography is only just developing. Undoubtedly, the many opportunities to create international collaborations are the most invigorating aspects of working in Singapore, and our group has developed strong links with groups in Australia, Europe and the US.”

Kum Fun Mok is one of the distinguished crystallographers in Singapore. After retirement from the Department of Chemistry, NUS, he established the X-ray Crystallography unit for the Division of Chemistry and Biological Chemistry, NTU along with his former student Yongxin Li.
Reginald B.H. Tan is the Programme Manager of Crystallization and Particle Science at the Institute of Chemical & Engineering Sciences (ICES). ICES is one of the twelve research institutes of A*STAR. He obtained his PhD in chemical engineering from the University of Cambridge and his research interests include modeling of transport phenomena, crystallization and formulation sciences. He also holds an Associate Professorship in the Department of Chemical & Biomolecular Engineering (ICES) at NUS. At ICES he leads a team of more than 20 scientists and engineers in investigating crystallization and formulation sciences from fundamentals to industrial applications. His team is currently studying the fundamental scientific principles underlying nucleation and crystallization phenomena, with the aim of controlling crystal size, shape, form, purity and formulability. He is also implementing his results for industrial applications with the aid of process analytical technology (PAT). In the area of formulation sciences, Tan’s group is actively studying topics in particle formation and design, powder technology and interfacial phenomena related to pharmaceutical and fine chemical applications. He is also investigating novel formulations in potentially valuable areas, including co-crystals and nanoparticle drugs, functional excipients and direct precipitation of stabilized fine particles (see Fig. 2.4). Ning Shan is a Research Fellow at ICES interested in crystal engineering, crystallization and molecular modeling. He did his Ph.D. at Cambridge, UK and was a visiting engineer at the Massachusetts Institute of Technology in 2004-2005.
Chris Boothroyd is a Principal Scientist in the Institute of Materials Research and Engineering (IMRE, one of the institutes of A*STAR) where he is in charge of the electron microscopes. He has 24 years of experience in transmission and scanning electron microscopy including energy loss spectroscopy (EELS), energy filtered microscopy (EFTEM) and high resolution electron microscopy (HREM). In the past he worked in the electron microscopy group at the Department of Materials Science and Metallurgy, Cambridge, where his research covered a wide variety of topics related to electron microscopy. Currently he is interested in the quantitative measurements of contrast in HREM and its comparison with image simulations. His recent work has been on measurement of phonon scattering and its contribution to HREM using convergent beam and holographic methods.Apart from hardcore single crystal diffraction studies, several scientists are working on chemical vapor deposition, surface science problems such as self-assembly, reactivity of molecules, functionalizing metal surfaces, etc. Also, experimental techniques such as low energy electron diffraction (LEED), high resolution electron energy loss spectroscopy (HREELS), X-ray photoelectron spectroscopy (XPS), ultra-violet photoelectron spectroscopy (UPS) and Auger electron spectroscopy (AES) are also being used extensively.

Nobel Laureate Robert Huber is a visiting faculty member at the Department of Chemistry, NUS and teaches an MSc Industrial Chemistry course, jointly offered by NUS and the Technical University of Munich. He is a familiar face at the NUS campus.

Macromolecular crystallography

The density of charged amino acids per unit surface area is … oops, we are lost. Yes, now we remember. When you come to macromolecular crystallography, you will be surprised to know that the density of protein crystallographers in Singapore is significant! There are 9 protein crystallography labs on this tiny island. The first protein crystallographer to land in Singapore in 1997 was Prasanna Kolatkar (popularly known as PK), from Michael Rossmann’s lab. He did his Ph.D. at University of Texas at Austin and a Postdoc at Purdue. He is working on the structural Biology of transcription factors and proteins involved in stem cell and cancer biology and analysis of protein-protein interactions. He is now a senior investigator at the Genome Institute of Singapore, one of the A*STAR research institutes.
PK says, “My time in Singapore has been well spent as I have had access to funding at a reasonable level to do good science. In addition I have been able to recruit many talented people from around the world including Norway, Germany, India and China as well as the US over the years. In addition a growing pool of Singaporean talent has helped to fill manpower needs in the lab. We have been able to determine the structures of several interesting proteins including the fve mushroom protein (Fig. 3.1). We have also carried out structural bioinformatics related work dealing with protein-protein interactions and relationships of domains. I would like to see a much greater output of quality structures and interesting findings in the future. I also am hoping to better integrate my informatics and wet-lab portions of the lab to focus on transcription factors”.
The next to join the club in 1998 were Kunchithapadam Swaminathan (Swami) from the Wistar Institute, Philadelphia and Terje Dokland (now at the University of Alabama, Birmingham) from Purdue.

Swami says, “My first day in Singapore was laced with childhood memories. Interestingly, in third grade (1969) in my village school, a friend’s grandfather returned to our village after a trip to Singapore. In fact, we used to call him ‘the great man who traveled in a ship’. He presented me with a pencil with a small eraser attached at the end. Even today, this pencil is one of my most unforgettable surprises. After that I saw Singapore in several Indian films. However, I never had a chance to come here”.

Swami did his Ph.D. at the Indian Institute of Technology, Mumbai, India (1989) and post-doctoral research at Penn (1989-95) and the Wistar Institute (1995-97). Currently he heads two labs, one at the Institute of Molecular and Cell Biology and the other at the Department of Biological Sciences, National University of Singapore. “In one of the Scientific Advisory Board meetings, Nobel Laureate Sydney Brenner (who also has a lab at IMCB) joked with me that I am a bigamist. I just replied that I enjoy it! If I have to comment about science in Singapore, the efforts by A*Star, NUS and NTU to promote quality research and publication are wonderful. Funding is sumptuous. There is no problem for facilities, resources and freedom. At the same time the level of competition is challenging.”
Haiwei Song is another protein crystallographer at IMCB who came from Oxford University in June 2001. Julien Lescar came next. He was originally trained as a Physicist (University Paris XI, Orsay, France) but became gradually more interested in macromolecular recognition in the immune system through the study of antigen-antibody complexes during his Ph.D. and a Postdoc at the Immunology Department of the Pasteur Institute in Paris (1990-1996), In January 1997, he moved to the European Synchrotron Facility in Grenoble, where he took an active part in the development of the ID2 High Brilliance Bio-Crystallography Beamline, maintained by the European Molecular Biology Laboratory (EMBL). In September 1999, he was a research scientist at the University Joseph Fourier in Grenoble where he got involved in several studies on Protein-Carbohydrate interactions. In January 2002, he came to Singapore to take part in the launching of a new School of Biological Sciences at NTU. A schematic view of the dengue ns3 helicase catalytic domain structure from his lab is shown in Fig. 3.2.
Rupert C. Wilmouth is also a faculty member of the School of Biological Sciences, NTU. He got his Ph.D. and post-doctoral experience at University of Oxford. His field of research includes mechanistic crystallography, proteases, helicases and kinases. On the research experience in Singapore, Rupert says, “Very good: excellent new buildings, superb quality and quantity of research equipment, good level of grant funding. Main downside so far has been difficulty in reruiting researchers. My only wish list is a synchrotron suitable for protein crystallography in Singapore”! His structure of anthocyanidin synthase from Arabidopsis thaliana is shown in Fig. 3.3.
Our next player J. Sivaraman, who moved to Singapore in July 2003, did his PhD (1995) at Anna University, India and his post doctoral research (1995-2003) at the Biotechnology Research Institute, National Research Council of Canada, Montreal. “Singapore is an exciting place to do research because science has been targeted as a key to the country’s future development. This is especially true in the life sciences area, where many research opportunities are available at institutes, universities, and companies. In our lab we are focusing on the crystal structure and catalytic mechanism of several cysteine proteases of the papain superfamily, ribosomal RNA modifying enzymes and enzymes involved in carbohydrate metabolism”. His recent crystal structure of RluF is shown in fig. 3.4.

Bob Robinson (who is carrying his lab members on his head in the figure in the photograph) is from Lancashire, England and completed his B.Sc. in chemistry at King’s College, London University and an M.Sc. in the same subject at the University of British Columbia, Vancouver. After working at Regeneron Pharmaceuticals in New York, he undertook a D.Phil at Oxford University specializing in protein crystallography and and then did a postdoc at the Salk Institute, San Diego. Bob started the Actin Structure Laboratory at Uppsala University, Sweden. His group moved to IMCB in the spring of 2005 where he is an Associate Professor.

“IMCB provides a stimulating environment for science. I made the jump from a granting system to a fully funded Institute. In this system scientists can dedicate their time to doing science, rather than hypothesizing about what they would like to be doing, and target questions without excessive limitations of time and resources. We are pretty much only limited by our own abilities and imaginations.”

Bob’s main interest is in understanding the mechanisms behind cell movement. The Lab focuses on actin polymerization machinery (related structures above), which provides the force during cell locomotion. “We use protein crystallography to determine the shape of key molecular complexes that regulate the spatial and temporal patterning of actin assembly and disassembly. In the long term we would like to design drugs to interfere with these processes, with the aim of stopping pathogens and cancer cells from invading tissues or to speed up the recruitment of repair cells to wound sites.”

Curt Alexander Davey [Ph.D., Univ. of Miami School of Medicine, USA (1996), Postdoc, Univ. of Miami, USA (1996-1997), staff scientist postdoc, ETH-Zurich, Switzerland (1998-2003)] is now an Assistant Professor, Division of Structural & Computational Biology, School of Biological Sciences, NTU. “My lab is interested in the molecular and atomic details of how the expression of genetic information is regulated. Our main focus is on structural characterization of large DNA-protein assemblies, such as the nucleosome core particle of chromatin, using primarily X-ray crystallography. In particular, we are studying the relationship between DNA sequence, protein binding, and the resulting DNA conformation, and how this protein-bound DNA conformation influences association of small molecules or additional protein factors.

In Singapore, research in the biological sciences is on the rise. The current funding atmosphere holds special promise for investigators who are embarking on novel research avenues or engaging in unique interdisciplinary ventures. For the hard-core X-ray crystallographer, the only major item to wish for would be to have our own macromolecular synchrotron facility!”

The latest addition to our club is Adam Yuan (another bigamist) from Memorial Sloan Kettering Cancer Center, New York. He will have a joint appointment with Temasek Life Science Laboratory and the Department of Biological Sciences, National University of Singapore.

Singapore Synchrotron Light Source (SSLS)

Don’t you think the wish of all crystallographers for a synchrotron in Singapore should be fulfilled? Yes, Singapore now has its own synchrotron. According to Herbert O. Moser, Director of SSLS, “Singapore is a special place for synchrotron radiation. Due to the strong concentration of high-tech industries and the high level of scientific research and education there is a huge potential for synchrotron radiation applications. The mission of SSLS is to bring synchrotron radiation into industrial, institutional, and academic daily life in order to add value to the wealth-creating process”.

The Singapore Synchrotron Light Source (SSLS, http://ssls.nus.edu.sg) is a university-level research institute at NUS. It is dedicated to generating and exploiting synchrotron radiation for research and development purposes and provides services for customers including research institutions, industry and institutions of public interest. At present, synchrotron radiation is produced by a compact 700 MeV electron storage ring with two 4.5 T superconducting dipoles. It covers a spectral range of 7 orders of magnitude from hard X-rays to the far infrared. Five beamlines and experimental stations are in operation comprising a micro/nano-manufacturing facility (LiMiNT), a phase contrast imaging and tomography beamline (PCIT), a soft X-ray facility for surface, interface, and nanostructure science (SINS), a hard X-ray facility for diffraction, absorption spectroscopy and fluorescence (XDD, X-ray demonstration and development) and an infrared spectro/microscopy facility (ISMI). A further beamline for electron beam diagnostics will be ready in 2006. This portfolio of experimental facilities makes SSLS rather attractive for a wide variety of research disciplines including biomedical engineering, catalysis, data storage, environmental science and engineering, life sciences, materials science and engineering, micro/nanotechnology and semiconductor manufacturing.

The XDD beamline was designed for general-purpose diffractometry including high-resolution diffractometry, powder diffractometry, reflectometry, and topography. It also features XAFS (Xray absorption fine structure). With high-resolution diffractometry, precise structural parameters, minute strain status, composition, thickness, surface/interface roughness and texture/stress analysis for crystalline materials can be obtained. Powder diffractometry makes possible crystal structure determination and refinement, phase identification both in quality and quantity, precise lattice-parameter determination, measurement of crystal grain size & texture/stress analyses. With grazing-incidence-diffraction, reflectometry and diffuse scattering, information on surface and interface structure ordering, as well as surface phase identification/transition can be obtained. XAFS can offer information on neighboring coordination and valence status in a complex, particularly for non-crystalline materials.

SSLS has proposed to disentangle the methods currently combined in XDD and to build dedicated beamlines for powder diffraction, for long-wavelength macromolecular structure determination enabling phasing from phosphorus up (2.149 keV) and for X-ray absorption fine structure spectroscopy, all of them serving research institutes, universities, and industry, locally as well as regionally. They are also slowly expanding in other areas like XAFS, XANES (X-ray absorption near edge structure) and reflectometry.

Conferences, meetings and workshops

Asian Crystallographic Association Meeting (AsCA’92): The Inaugural AsCA Conference was held in Singapore, in November 1992. The Crystallographic Society of Japan and the Society of Crystallographers in Australia and New Zealand supported this by holding their annual meetings at AsCA’92. Syd Hall of Western Australia was the conference chairman and Lip Lin Koh chaired the local organizing committee. The then President of the IUCr, Andre Authier, attended the meeting. The total registration was 320 from more than 20 countries with 260 full participants and 60 students, excluding 30 accompanying persons. The scientific program consisted of 16 oral sessions with 73 papers and 22 poster topics with 190 papers.

Singapore National Crystal Growing Challenge: The crystal growing challenge has been very popular among students from secondary schools, junior colleges and polytechnics in Singapore. In this challenge the students have an opportunity to show their creativity and learn about the science and art of growing crystals. The crystal growing challenge is designed to reveal the importance of the technique, to show that science can be fun, and to get students interested and involved in scientific activities at a young age. NUS and the Singapore National Institute of Chemistry organize this event which was initiated by J.J. Vittal in 1997 and conducted with the support of the Department of Chemistry at NUS. Since 2000 it is conducted once in two years. The 6^th challenge was conducted in September 2004 with a record number of participants (168 entries from 68 educational institutions). The number of entries has doubled since the first challenge. Each year we are challenging these young minds with new innovative crystal growing challenges such as crystals inside crystals, the longest single crystal, cubic or tetrahedral shaped NaClO₃, bluish-green NiSO₄.6H₂O but not greenish NiSO₄.7H₂O. The students have responded well to these challenges. This has been generously sponsored by various agencies from time to time but George Tang of Bruker Singapore has been a constant supporter of this event ever since it started. The winning crystals are kept in display cabinets decorating the chemistry department for two years until the next challenge. Details of the current challenge (September 2006) are available at the website: www.chemistry.nus.edu.sg/ncgc1.htm.

New Materials by Crystal Engineering Design Symposium: This symposium, which was one of the symposia of the International Conference on Materials for Applied Technologies (ICMAT 2003), was organized by J.J. Vittal, Edward R.T. Tiekink and Suresh Valiyaveettil during December, 2003. Covered topics included prediction of crystal structures, polymorphism, metal coordination polymers, and magnetic and optoelectronic materials. A highlight of the meeting was a session to honor Richard Robson for his contributions to crystal engineering. Over 70 registered delegates from 17 countries presented 44 oral presentations in 11 scientific sessions over 5 days and featured 3 poster sessions.

International Conference of Structural Biology: The Department of Biological Sciences hosted three International Structural Biology Conferences (2000, 2002 and 2004). The participants of the 2004 conference included Jack Johnson, Susan Taylor and Roger Tsien. Very importantly, in the 2004 conference they conducted a 3 day crystallography workshop that covered all aspects of crystallography. The workshop was free and about 50 graduate students from countries like India, China, and Malaysia attended. The Department of Biological Sciences is now gearing up for the 4th conference in December 2006.

By now you might have realized that most Singaporean crystallographers are active, enthusiastic and striving hard to achieve their best. Each time you see the name Singapore, we hope you will remember us. Next time you cross Singapore or plan a wonderful vacation here, along with your rush to enjoy curried fish-heads or pepper crabs, please plan to give a seminar at NUS, NTU or any one of the research institutes of A*STAR!

Kunchithapadam Swaminathan and Jagadese J. Vittal

Singapore’s leading crystallographer

Lip Lin Koh is the most distinguished X-ray crystallographer in Singapore. He received his B.Sc. degree from Nanyang University in 1959 and Ph.D. degree from Boston University in 1964 on the crystal structure of tris(p-aminophenyl)carbonium perchlorate which was published in Acta Cryst., B27, 1405-13 (1971). He taught at in the Department of Chemistry at Nanyang University (1964-79) and at NUS (1980-96). He was the first Dean of Science at NUS (1981- 85), and had previously served as Head of the Department of Chemistry and Dean of Science at Nanyang University, before the merger of Nanyang University and University of Singapore. Apart from his enduring contributions to the university, he also provided service to the public. From 1979 to 1996, he was an elected Member of Parliament of Singapore, playing his part in national policies. He also served the University as a member of the Council. He is currently the president of the Singapore Association for the Advancement of Science. After his retirement from the Department of Chemistry, he was engaged as a part-time research fellow at CE Resources Pte Ltd, an NUS spin-off company.

He rejoined the Department as an Adjunct Senior Research Fellow in 1992, offering selfless guidance to staff and students on solving crystal structures. He was the first Singaporean to serve as a co-editor of the scientific journal Acta Crystallographica (during the period 1994-97). He organized the first AsCA Meeting in 1992. He has been helping the Singapore National Crystal Growing Challenge organizers in selecting the winners.