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Edward R. T. Tiekink
Research Interests
Positions AvailableIf the information above or in any of the related sites interests you, Opportunities for financial support are available on a competitive basis. Tiekink group - Spring 2008
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Edward R.T. Tiekink is a graduate of The University of Melbourne (Ph.D., 1985), majoring in Inorganic Chemistry/Crystallography. He has gained most of his academic experience at The University of Adelaide and joined UTSA in the Fall (Autumn) of 2005 after a stint at Griffith University as a Smart Returns Fellow sponsored by the Queensland Government. His research interests revolve around chemical crystallography with an emphasis on main group element chemistry, but not exclusively. This is complemented by research into the development of metal-based drugs for the treatment of cancer (Au & Bi), rheumatoid arthritis (Au) and tropical diseases (Sb & Bi). He has published over 900 research papers, reviews, book chapters, etc. and currently serves as co-/associate-editors of Acta Crystallographica E, Applied Organometallic Chemistry, Bioinorganic Chemistry & Applications, and Zeitschrift für Kristallographie. The research interests of our group are conveniently divided into two themes but, inevitably, there is some overlap between these. The themes are i) metal-based drugs and ii) chemical crystallography. Our research in metal-based drugs is motivated by the desire to generate novel metal-containing chemical compounds that have a greater efficacy and reduced deleterious side-effects in the treatment of human ailments such as rheumatoid arthritis, various forms of cancer, and different types of viruses. While it might seem a little odd that one might wish to use metal-containing species as drugs, for example for fears of toxicity, it turns out that metal-based drugs have been used since antiquity for the simple reason: they work where other treatments fail. A recent book we co-edited with Prof Marcel Gielen (Vrije Universiteit Brussel) highlights the many and varied uses of metal complexes in all aspects of medicine; see http://eu.wiley.com/WileyCDA/WileyTitle/productCd-0470864036.html. The success of metal-based drugs might be due to several reasons. An advantage of metal-based drugs is that they might serve as a carrier to deliver/transport pharmacologically active substrates to diseased sites, owing to altered metabolic pathways, different solubility profiles, slow release mechanisms, etc. In this application, the metal species has no direct role in curing the disease but rather functions as a platform for drug delivery. Alternatively, the metal may be the therapeutic agent, i.e. essential for efficacy. A good example of this is found in cisplatin, a very widely used platinum-containing anti-cancer drug, where is it known that the metal centre complexes DNA, disrupting cell division leading to cell death and cure for cancer, in favourable outcomes. Our research achievements are found in recent reviews and patents (see Tiekink group publications). CLICK HERE for a listing of recent relevant publications. We are always looking forward and at present, our work is focussed upon generating novel ways of delivering gold for the treatment of rheumatoid arthritis, designing gold and bismuth complexes with anti-tumour activity and, especially, developing novel main group element species for the treatment of viruses and tropical diseases. The second major focus of our research revolves around chemical crystallography. Here, we are able to determine the three-dimensional structure of molecular species using X-ray crystallographic techniques and use the derived information to determine novel chemical structures, rationalise physical and chemical properties, etc. A particular emphasis of our work revolves around the desire to understand the interplay between the molecular structure and the host crystalline environment in which the molecule finds itself. Thus, using a systematic approach where crystallographic results are compared with spectroscopic results and theoretical calculations, we are able to delineate the influence of crystal structure upon molecular structure. This knowledge is pivotal in enabling the rational design of crystal structure, i.e. crystal engineering. "Just as synthetic chemists desire to form bonds between designated atoms to synthesise specific molecules, the crystal engineer desires to take molecules and to arrange these is a specific manner in the solid-state, a most challenging quest; see (http://www.wiley.com/WileyCDA/WileyTitle/productCd-0470022582.html) for a recently published book edited by Tiekink and Vittal on Crystal Engineering. A beautiful example of the principles for crystal design developed by our group is illustrated by the following. The idea of steric control over supramolecular aggregation is nicely illustrated in the series of three binary zinc xanthate structures, i.e. of empirical formula Zn(S2COR)2 [1]. Here, when the xanthate-bound iso-propyl group is present, isolated tetrameric squares are found in the solid state as shown in the view below.
Reducing the size of the R group to n-propyl now allows greater access to supramolecular aggregation so that a chain motif is found as shown in the view below-left. Finally, reducing the size of the R group even further to ethyl, results in the formation of a 2-D motif, as in the view below-right.
The motivation for such “molecular materials chemistry” is to generate new molecular materials with applications in fields as diverse as electronic devices, magnetic materials, separation science and catalysis. This is because the chemical and physical properties of isolated molecules or even solvated molecules in a solution must be, by definition, different to those exhibited by a collection of molecules existing in a crystalline manifold, i.e. in the condensed phase. So, over and beyond determining the principles of crystal packing, as outlined above, many of our new systems, in particular those containing gold, zinc and cadmium, show luminescence characteristics giving extra impetus to our work. For example, red-shifts in solid-state emission spectra are controlled, in part, by the designed topology of di-imine base adducts of zinc(II) xanthates.
We are also interested to discover the role between the nature of precursor structure and the morphology of nanocomposites generated by thermal degradation. An example of this is beautifully illustrated below.
However, when a polymeric bismuth(III) xanthate precursor is used, e.g. Bi(S2COR)3 for R = i-Pr: microcrystals are formed under the same conditions: CLICK HERE for a listing of recent relevant publications; please go to the link for “Tiekink publications” for a full listing. Prospective members of our group are encouraged to contact me directly (Edward.Tiekink@utsa.edu) for more details of our current interests. |
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