The newest member of the CrystEngComm Editorial Board talks to CrystEngCommunity about Crystal Explorer and kangaroos
18 September 2009
Mark Spackman is a professor at the University of Western Australia and is also involved in many crystallographic associations.
His research focuses on bridging the gap between theoretical and experimental determinations of molecular properties and the use of tools and methods from computational chemistry to inform aspects of modern crystallography, especially crystal packing.
1) Why did you to become a scientist?
I guess I have a curious mind, wanting to know about all manner of things and understand how they work and fit together. As a child I remember playing with chemicals, producing hydrogen to propel rockets, burning sulphur, and melting lead. This is so obviously dangerous now, but I was fortunate enough to grow up in a world where children were given the freedom to explore their surroundings in all sorts of ways that now seem impossible. I remember long bike rides with friends in the New Zealand countryside, and getting to know the spectacular geography, the native flora and the wonderful birds. And like many chemists I know, I was also turned on to chemistry by an enthusiastic high school teacher who included all manner of chemical demonstrations in his classes. Those days school students were allowed to undertake experiments that are mostly off limits now. Curiously, I ended up pursuing mostly theoretical and computational research, probably because I discovered that others were much better at experiments than I was, and also because I wanted a deeper understanding than experiments alone could provide.
2) What projects are you working on at the moment?
We are working on the further development of Hirshfeld surface and related tools with our software CrystalExplorer, and experimental charge density studies of some of the fundamental host-guest systems like hydroquinone clathrates and crown ether complexes. We have so many more ideas for CrystalExplorer, for example the characterization of voids in molecular crystals, mapping of a variety of other interesting properties on molecular surfaces, and linking these visual and qualitative tools to the computation of intermolecular interaction energies. For the host-guest systems I’m interested in finding out whether experimental charge density analysis is capable of yielding accurate information on properties of guest molecules, such as dipole moments, and their relationship to the crystal field they experience in different hosts.
3) What do you think will be the next big breakthrough in your field?
What field do I consider myself to be in? I used to be very much involved in charge density research, in particular the detailed analysis and modelling of X-ray diffraction data, but I’ve also worked a great deal on the critical comparison between theory and experiment for a host of electrical properties of molecules. The common thread in all of this has been a focus on molecules, their properties, and their relationship to the structure and properties of molecular crystals, so in a sense it was natural for this to lead to crystal engineering. I’m not a great believer in big breakthroughs, but I do think that we are beginning to see less of a focus on descriptions of crystal structure, and more attempts to understand the key factors that determine why one (or several) structures are observed, and not a multitude of other possibilities. In line with this is an increasing awareness that molecules in crystals are not static (molecular cemeteries) – and their motion and even disorder will often play an important role in determining not just which crystal structures form, but even their bulk properties.
4) How do you think crystal engineering will develop in the next five years?
I would like to see this deeper understanding of intermolecular interactions translated into an appreciation of the relationship between the properties of molecules, their crystal structure, and the properties of the bulk. We’ve recently explored this by looking into linear and nonlinear optical properties of molecular crystals, and their relationship with the molecular polarizabilities and hyperpolarizabilities, and in particular the changes to those properties brought about by the crystalline electric field. For me this work highlighted the widely under-appreciated importance of the magnitude of electric field experienced by molecules in close proximity to one another. These fields can be three orders of magnitude greater than we can apply to crystals in the laboratory, and their consequences reach far beyond molecular crystals and crystal engineering, and into the fundamentals of molecular recognition and protein-ligand binding.
5) What is the most rewarding aspect of your work?
Discovering new things and working with enthusiastic colleagues. I still get excited by new results from experiment or computations, especially results that tell us something we weren’t expecting. On a personal level, one of the most rewarding aspects of involvement and participation in an international scientific community, especially in crystallography, is that so many of the colleagues I’ve met and worked with over the years have become great personal friends.
6) What is the secret to a successful research group?
I’ve never had a large research group, and at times have been working pretty much by myself. But developing and maintaining good relationships with colleagues, co-workers and students has always been important to me. Providing strong support and effective mentoring to students and young post-doctoral workers is absolutely essential.
7) What achievement are you most proud of?
I would have to say our work on Hirshfeld surfaces and the developments that have evolved from that very simple idea. I still find it astonishing that such a simple concept was not discovered before we stumbled on it in 1996, and I’m extremely pleased with the way it has grown from the germ of an idea to a freely available multi-platform software package that embodies this novel approach to crystal structure analysis. It is also extremely satisfying to see that other researchers find these tools useful in their own work. Of course this is far from my work alone – it has been a joint effort with many others, in particular Josh McKinnon and Dylan Jayatilaka, and I’m extremely fortunate to have been able to collaborate with these very talented people.
8 ) What advice would you give to a young scientist?
Don’t just follow what others are doing. Be inventive and original, and pursue a path less travelled. Make sure that you enjoy what you do! And I can’t think of any more important advice than to be persistent in pursuing your goals and try not to be discouraged by negative comments or temporary setbacks. This is especially applicable to research funding these days.
9) What would you do if you weren’t a scientist?
I think I would always be a scientist of some kind. Perhaps if things had been different I might have become a geologist, or even a botanist.
10) Can you tell us a little known fact about yourself?
As a graduate student I played a lot of volleyball, and this continued while a postdoc in America, where I played for Carnegie-Mellon as well as socially. Because I had a naturally high jump, and because I came from Australia, I earned the nickname of “kangaroo”.
Related Links
Mark Spackman’s homepage University of Western Australia
Visualisation and characterisation of voids in crystalline materials
Michael J. Turner, Joshua J. McKinnon, Dylan Jayatilaka and Mark A. Spackman
CrystEngComm, 2011, 13, 1804-1813
Revised electrostatics from invariom refinement of the 18-residue peptaibol antibiotic trichotoxin A50E
Birger Dittrich, Charles S. Bond, Roman Kalinowski, M. A. Spackman and Dylan Jayatilaka
CrystEngComm, 2010, 12, 2419-2423
