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Free Radicals Rock!

Posted on 13/10/2008

Free radicals are everywhere, causing ageing related illnesses in people, the deterioration of plastics, the fading of paint in houses, the degradation of works of art, and can contribute to heart attacks, stroke and cancers.

Normally the unpaired electron in the radical is the most reactive part of the molecule and it is this reactivity that can have dire consequences at the molecular level. "Imagine our surprise when we discovered classes of free radicals in which the unpaired elecron is not the most reactive bit", says Dr Uta Wille, Chief Investigator in the Melbourne node of the Centre.

"We were looking at the reaction trajectory of silicon-based radicals in their reaction with certain substrates when we noticed an unusual rocking and rolling motion in the computer simulation”. “It was a bit like looking at a couple dancing to a rock and roll rhythm”, remarked Professor Carl Schiesser, “we immediately knew that something strange was going on”. It's not every day that one discovers a new phenomenon in free radical chemistry.

Now termed “the dual orbital effect” or “multi-component orbital effect”, this discovery, made possible with the aid of high-performance computing using quantum chemical techniques, effectively allows radicals to masquerade as non-radical species, taking advantage of the chemistry of both radical and non-radical entities. “But it only works when the conditions are right”, says Sara Kyne, a PhD student working on the project, “the radical and its reacting partner need to be matched energetically”.

This work has led to an active collaboration between Centre researchers and colleagues in Osaka Prefecture University (OPU) in Japan.

“This discovery allows us to better explain many observations in radical chemistry that previously were either unexplained, or were explained in a hand-wavey sort of way”, say Professor Ilhyong Ryu of OPU, "but most importantly, it can be exploited by us in the synthesis of molecules, many of which are biologically relevant”.

“Whatever use this discovery is put to, it cannot be denied that Centre researchers discovered a new fundamental phenomenon and that’s exciting and it further highlights Australia’s strong position in the field”, says Professor Carl Schiesser.