Research Fellows Directory
Professor David O'Hagan FRSE
University of St Andrews
Organic fluorine compounds are hardly found as natural products in mammals, plants and bacteria. On the other hand if we consider industry, we find that fluorine is present in about 20% of all pharmaceutical products on the market, about 30% of all agrochemicals and is a very important constituent of polymers such as the non-stick material PTFE (Teflon). Thus incorporation of fluorine into organic compounds leads to stable, polar compounds, and molecules can be electronically tuned by replacing eg –H or –OH for –F, but without a major change to the shape of the molecule.
We have an interest in the phenomenon of fluorine. It is the most electronegative element and it draws electron density towards it. This makes it small and it is the next largest element to hydrogen that can be covelently bound to carbon. Thus we like to play games and replace fluorine for hydrogens to see how this influences the properties of a molecule. The ability of fluorine to pull electrons towards it can lead to a stiffness when fluorine is incorporated into molecules, and this stiffness results in mobility limitation. This year we have explored this with musk fragrances, to try to assess the shape of the molecule that will provide the best musk scent. The natural musks do not contain fluorine. This involved a major synthesis effort in the lab to make the desired molecules, and then these molecules were tested by a top fragrance company in Switzerland (Givaudan Ltd.). We received good results and got some pleasant odours and some less pleasant. X-Ray structure and computational analysis then allowed us to suggest favoured conformations to trigger musk odour. So we beleive we are helping to understand the secrets of a good muck scent.
Interests and expertise (Subject groups)