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Chemistry at McMaster University.

Participants in the 74th Canadian Chemical Conference and Exhibition will have the opportunity to acquaint themselves (or renew acquaintances, as the case may be) with the Chemistry Department at McMaster University, where much of the conference organization has taken place.

The chemistry department at McMaster has undergone many changes in recent years. While several of our internationally-known colleagues have retired, we have grasped the opportunity afforded by the recent NSERC University Research Fellowship programme to attract some talented young scientists, whose early promise is now bearing fruit. In fact, we boast the best track record in the country for attracting URFs in chemistry: they include Gary Schrobilgen (inorganic); Adam Hitchcock, FCIC (physical); Willie Leigh, MCIC (organic); Michael Brook, MCIC (organic); Tim Wildman, MCIC (physical); and Randy Dumont, MCIC (physical). Moreover, we were able to persuade Geraldine Kenney-Wallace, MCIC, to leave the chair of the Science Council of Canada and come to McMaster; she joins a long line of distinguished chemists who have become university presidents, not only here but elsewhere in Canada.

We have long had a tradition of research excellence but, in these days of financial stringency, it takes real determination to attract high-calibre faculty and the necessary equipment to remain at the forefront. One way in which McMaster has responded to these realities has been through the establishment of institutes. These promote interdisciplinary research collaboration and graduate education. One example is the McMaster Isntitute for Materials Research (MIMR), comprised of scientists from chemistry, physics, geology, nuclear medicine and engineering, with many common interests and equipment requirements. The particular effectiveness of such organization is perhaps best exemplified by the way we were able to respond to the recent breakthroughs in the field of high-temperature superconductors. The MIMR is a world leader in this field, as a result of the combined expertise of solid state physicists (both theorericians and experimentalists) and synthetic solid-state chemists such as John Greedan. This group employs neutron diffraction studies and a variety of other methods to characterize these fascinating new materials. Another example is the McMaster Institute for Polymer Production Technology, which consists of a group of polymer scientists from the Departments of Chemistry and Chemical Engineering.

Inorganic Chemistry

Professor emeritus Ron Gillespie, FCIC, established one of the world's best schools of main group chemistry, and these traditions continue at McMaster. Among the exciting recent developments are Schrobilgen's krypton-nitrogen compounds and -- perhaps even better from the pedagogical viewpoint -- his synthesis of [XeF.sup.-.sub.5], which VSEPR predicts to be the first pentagonal planar system; the [D.sub.5h] structure has now been confirmed by X-ray crystallography.

The inorganic chemists make extensive use of high field NMR spectroscopy (more than 50 different nuclei are run on a regular basis) and our 500 MHz and 250 MHz instruments play a crucial role in this regard. [1] Such techniques are essential in gaining an understanding not only of structures (eg. metal complexes of steroids and terpenes) but also of molecular dynamics. For example, the long-standing controversy over the barriers to tripodal rotation in arene-complexes has been resolved by McGlinchey via a low-temperature NMR study of the chiral cation [[(C.sub.6.Et.sub.6]) Cr(CO)CS)NO][.sup.+], which exhibits 18 different [.sup.13]C resonances, one for each carbon in the ligand.

Bio-inorganic and medicinal chemistry is another inter-disciplinary area and again demonstrates the collaborative nature of many graduate thesis projects. Among the more striking examples are Colin Lock's, FCIC, work with gold derivatives which function as anti-arthritic drugs, his numerous X-ray structures of platinum-amine complexes related to cis-platin (an effective agent against some forms of cancer) and the use of technetium-99m for medical imaging purposes. Moreover, Schrobilgen's fluorine chemistry is not simply an academic curiosity; his group has developed novel methods of incorporating radioactive [sup.18.F] into dopa and other molecules related to the treatment of Parkinson's disease.

Powder diffraction methods as well as single crystal techniques are also being used by Jacques Barbier, whose main interests are in crystal chemistry and polymorphic transformations. Greedan also makes extensive use of these facilities in his solid-state studies of inorganic oxides and fluorides and superconducting materials.

Physical and Theoretical Chemistry

Good theory is essential both to interpret experimental results within existing frameworks and to provide predictions which, through experimental tests, can expose the limitations of current chemical understanding. Richard Bader and his group have developed a theory of molecular structure based on rigorous quantum mechanical principles. This approach allows us to define atoms and bonds precisely in terms of the topological properties of the charge density.

Dumont's research interests are in the general area of theoretical reaction dynamics. His main goal is to develop general statisical theories (or refine existing ones) to better understand reaction kinetics and dynamics in both the 'smooth' and 'chaotic' regimes.

The blending of theorerical with experimental methods is rapidly gaining importance as computers become cheaper and increasingly powerful. One obvious area in which theory and experiment are combined is pulse NMR spectroscopy -- a topic which has blossomed almost exponentially in recent years. Alex Bain, MCIC has pioneered methods for determining the robustness of a variety of 2D experiments. That is, when we follow the standard pulse sequences, we need to know their limitations and where they can lead us astray. The application of some of these ideas to fluxional systems has led him into fruitful collaborations with his synthetic and mechanistic colleagues. Moreover, NMR methods of characterizing polymers in solution and in the solid state have been shown to have considerable industrial significance. Wildman employs NMR spectroscopy and theoretical methods to study molecular structure and the dynamics of hydrogen-transfer reactions. Photoelectron spectroscopy (PES) is another are which relies heavily on theoretical calculations. Nick Werstiuk, FCIC, though he has his feet firmly planted in organic chemistry, makes extensive use of semi-empirical and ab initio theoretical calculations in his structural studies of organic molecules by PES.

Experimental physical chemistry is extraordinary equipment intensive and, oftentimes, the best approach is to travel the world to gather data wherever and whenever it is available. Hitchcock's inner shell excitation spectroscopy required not only the equipment built here, but also data from synchrothon laboratories in North America and Europe. These data provide invaluable probes for a wide variety of problems, ranging from biological interactions to improved semiconductor device materials.

Kenney-Wallace uses her research time to pursue her interests in chemical and physical phenomena in the picosecond and femtosecond time domains. She is developing ultrafast laser techniques and focusing her efforts in understanding non-linear optical phenomena; femtosecond tuneable lasers provide the means for real-time probing of materials and devices.

Peter Dawson's research interests are in the area of durface chemistry and heterogeneous catalysis. His studies employ a number of instrumental techniques, such as low energy electron diffraction, Auger electron spectroscopy, and thermal desorption mass spectometry.

Analytical Chemistry

Our analytical graduates have opportunities not only to develop novel qualitative and quantitative techniques but also to put them into direct practical use. While Ed Hileman's, FCIC, group focus their attention on the industrial aspects of hydrogen and dulfur co-production from recovered [H.sub.2]S, they are also developing expertise in fundamental and applied electrochemistry.

Hans Terlouw, MCIC, functions as a member of the analytical faculty as the director of the regional facility for mass spectrometry. The facility currently houses two sophisticated magnetic defletion-type instruments, equipped with EI, CI, and FAB ionization modes and a small benchtop Quad GC/MS instrument. This equipment is used for structure analysis by mass spectrometry and studies of the chemistry of ions and neutrals in the gas-phase.

In terms of public perception, however, perhaps the most widely-known of the department's recent analytical activities have been Brian McCarry's, FCIC, bio-assays to study the environmental effects of the burning of millions of tires in the enormous fire at Hagersville, Ont.

Organic Chemistry

McMaster has always enjoyed a very strong reputation in organic chemistry, and this promises to continue or even expand in the future. Professors emeriti Dave MacLean, FCIC, and Ian Spenser, FCIC, though now formally retired, continue to maintain strong research efforts in natural product chemistry and biosynthesis, respectively. MacLean is internationally known for his work in alkaloids identification and synthesis, and the use of mass spectrometric methods in the structure elucidation of alkaloids and oligosaccharides. Spenser has pioneered the use of isotope tracer methods in studies of the biosynthesis of nitrogen-containing natural products, such as vitamin [B.sub.6].

Russell Bell, FCIC, widely known for his early studies of the use of the nuclear Overhauser effect in organic structure elucidation by NMR, is currently involved with the synthesis and NMR spectroscopy of heteroaromatic cyclophanes, focusing on the aromatic heterobases present in RNA and DNA. Brook's interests are focused on synthetic and mechanistic aspects of aorganosilicon chemistry. While his early work at McMaster was concerned mainly with silane reductions and the chemistry of [beta]-silycarbocations, he is currently more active in the synthesis and chemistry of novel silicon-containing polymers for potential use as water purification membranes, conducting polymers, and slow-release drug matrices. The research interests of Paul Harrison, MCIC, who joined the department in 1989, are in the areas of bio- and biomimetic synthesis and the design and synthesis of enzyme inhibitors. Harold Stover, MCIC, another young faculty member who recently joined the department, is interested in the synthesis and study of novel organic polymers. Particular projects include studies of star polymers, prepared by living anionic polymeration, and the chemical modification of polymers. Department chairman McCarry is a bio-organic chemist known for his work in the synthesis of protein-labeling reagents, receptor agonists and antagonists, and studies of PAH metabolism. His current interests focus on organic analytical and environmental chemistry.

Physical-organic chemistry and photochemistry are strongly represented at McMaster, particularly in the area of organic reactive intermediates. John Warkentin, FCIC, widely respected for his work in free radical chemistry, is now most actively studying mechanistic and synthetic aspects of carbene chemistry. His work revolves around the chemistry of oxadiazolines, which he has shown to be exceedingly versatile precursors of carbenes (upon thermolysis) or diazo compounds (upon photolysis).

Werstiuk is renowned for his expertise in H/D exchange processes. His so-called 'high temperature-dilute acid' (HTDA) method for H/D (and H/T) exchange makes it possible to synthesize isotopically-labeled molecules with remarkably high specificity and in very high yields. One recent, particularly remarkable example is the synthesis of deuterium-labeled indomethacin, a non-steroidal anti-inflammatory drug used in the treatment of arthritis.

Terlouw recently joined the department after gaining an international reputation in organic mass spectrometry at the University of Utrecht. With the aid of a recent major equipment grant, he has just completed the installation of a custom-built BEE/Quad double focusing mass spectrometer. This instrument has been specifically designed for the further development of the technique of neutralization-reionization mass spectrometry (NRMS). This novel branch of mass spectrometry not only holds considerable promise as an analytical tool in structure analysis based on MS/MS-type experiments, but it also permits the generation and identification of unusually reactive, yet thermodynamically stable, species which cannot be sythesized in the condensed phase.

Ron Childs, FCIC, has an international reputation for his studies of homoaromaticity and thermal and photochemical pericyclic reactions of carbenium ions. His most recent efforts have been directed towards solid-state NMR and x-ray crystallographic studies of isolable carbocations, the thermal and photochemistry of iminium salts related to the visual pigments, and the use of photochemical methods for the fabrication of charge-mosaic piezodialysis membranes.

Leigh's research interests lie in the general area of organic photochemistry. He's best known (or would like to think he is) for his recent studies of the photochemistry of cyclobutenes and other strained hydrocarbons of theoretical importance -- in spite of what the textbooks say, the photo-chemical conversion of cyclobutene to butadiene apparently does not follow orbital symmetry selection rules! His other areas of interest include the photochemistry of solutes in organized media such as liquid crystals and cyclodextins and the study of reactive (transient) organosilicon compounds. These studies make freuent use of nonsecond laser flash photolysis methods, and are carried out on his recently completed, home-built system.

Many organic chemists in the department pursue active collaborative research projects with each other, and with scientists in other diverse areas. This is particularly true in polymer chemistry, which is rapidly becoming an area of intense activity in the department. [2] Brook, Stover, Childs anbd McCarry are all associated with the McMaster Institute for Polymer Production Technology, and have ongoing collaborations with other colleagues in the chemistry and chemical engineering departments. By and large, this research is funded substantially by grants from industry and accompanying NSERC matching funds. Werstiuk's UV photoelectron spectrometer and Leigh's nanosecond laser flash photolysis system are also frequently the central instruments in collaborative studies of reactive intermediates in organic as well as inorganic chemistry. Bell maintains active joint ventures with colleagues in the biochemistry, radiology, and nuclear medicine Departments, providing the synthetic and (most of the) spectroscopic expertise in studies of NMR imaging reagents.

The 'McModular' Graduate Curriculum

Increasingly, the somewhat artificial lines of demarcation between the traditional areas of chemistry are disappearing, and we have chosen to reflect this in our graduate course programme. To allow graduate students to follow the most useful selection of courses for their own particular needs, we have recently instituted a new graduate curriculum, in which traditional graduate courses have been replaced with a large number of six-week 'modules'. This approach to graduate chemistry teaching is unique in the country. Its remarkable success is reflected in the fact that a number of other departments at McMaster are now altering their gradutae programmes to follow our model.

In many areas, six weeks is obviously too short a period in which to present a given topic in enough depth to satisfy the specialist. This problem has been met by establishing 'linked' modules, which can be taken in a coherent sequence, in a number of subjects. Typically, most graduate students would take the one-dimensional NMR module, many would continue with that concerned with 2D-techniques, and a subset of these people would select a multinuclear magnetic resonance module and/or one discussing chemical exchange. By this means, one is not restricted to a few prescribed options, but rather each student can tailor-make her or his course programme to meld optimally with their research project. All full-time and associate faculty members of the department (research-active or not) are required to offer one graduate module per year. This results in a very large number of graduate courses being offered each year, and is the single biggest advantage of the modular curriculum.

We cannot end without mentioning Tom Birchall, whose untimely death from cancer left such a huge gap in our department; his contributions to main group chemistry and McMaster University cannot be overstated. The conference will include a symposium in his memory.

References

[1] D.G. Bickley, M.J. McGlinchey and G.J. Schrobilgen, Canadian Chemical News, 36, pp. 19-24 (January 1984).

[2] D.M. Keller, Canadian Chemical News, 43 pp. 13-17 (April 1991).
COPYRIGHT 1991 Chemical Institute of Canada
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1991 Gale, Cengage Learning. All rights reserved.

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Author:McGlinchey, Michael J.; Leigh, William J.
Publication:Canadian Chemical News
Date:May 1, 1991
Words:2509
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