04 February 2014
Materials to benefit from insight into the stability of crystals
A new project at the University of Copenhagen’s Department of Chemistry will make it easier to design materials with far more predictable and precise properties. Associate Professor Anders Ø. Madsen has received a four million kroner grant from the Villum Foundation to develop a combination of x-ray experiments and advanced computer simulations that will be able to predict the structure of a given material’s crystals.
Crystals decide taste of chocolate and effect of medicine
For everyone but chemists, crystals are usually associated with jewellery. But the durability of molecular crystals is decisive for the properties of a long list of materials. From chocolate’s ability to taste good, to a pharmaceutical product’s ability cure an illness, to the ability of an explosive to detonate when one wants it to. “Unfortunately, the properties and durability of crystals are determined by their structure and their structures cannot yet be predicted. Therefore, chemists are somewhat in the dark when designing new materials,” says Anders Østergaard Madsen, a chemist at the University of Copenhagen.
"Today chemists are somewhat in the dark when designing new materials!
Anders Østergaard Madsen
Department of Chemistry
University of Copenhagen
Crystal insight secure longevity
By investigating how crystals are formed in different materials, Madsen hopes that it will become easier to design products that can be stored without losing their desired attributes.
When medicine loses its potency or an explosive detonates upon the slightest touch, it is typically because the crystals within have changed form. Therefore, it is important to understand why and how small crystals transform from one structure into another.
Madsen explains: “Today, we have absolutely no control over how substances crystallise. It occurs almost haphazardly. Within pharmaceutical development, for example, enormous sums are spent to identify which crystal forms might emerge. My hope is that if we can understand what crystals are possible, and understand their properties and stability, we can produce better materials with specifically desired properties.”
Molecules chain dancing
The use of computers has expanded broadly across chemistry research and development to calculate how new substances ought to be combined in a flask. Still, the structure of crystals is outrageously difficult to calculate. This is partially due to the many molecules in a crystal, but also because the molecules within a crystal move. These fluctuating movements, known as phonons lessen the stability of a material.
“Molecules in a crystal lattice are a bit like folk dancers dancing a chain dance. We need to understand what the individual dancers are doing, as well as how the entire chain is moving, in order to describe the dance. The difference is that crystals are so small that we can only study them using radiological techniques,” explains Madsen.
Computing and experiment combined with new instrument
Anders Madsen’s project will combine the development of calculation methods and detailed laboratory experiments with crystals. The University of Copenhagen affords him the use of some of Denmark’s best-suited instruments for the task. The Department of Chemistry has recently purchased two X-ray diffractometers with help from the Villum Foundation. This makes it possible to peer deeply into the microscopic structures. And, with one of the diffractometers, he will be able to investigate crystals under temperatures varying from five degrees Kelvin (5 degrees above absolute zero) to 500 Kelvin (226.85 Celsius). The incredible temperature range is important in understanding how crystals vibrate, as the higher the temperature, the more they move.
Anders Ø. Madsen plans to use the Villum Foundation’s generous grant to cover his own salary for three years, as well as to hire a Postdoc for two-years.