Chemistry isn't about to be left out of the buzz surrounding the upcoming 2012 Summer Olympics in London. British chemists have collaborated with IBM Research - Zurich to develop and image a molecule just 1.2 nanometers wide that looks like the five Olympic rings.

Dubbed Olympicene the five-ringed hydrocarbon contains 19 carbon atoms and 12 hydrogen atoms. The formal name is pentacyclo[^{5,18}.0^{8,17}.0^{11,16}]nonadeca-1,3,5(18),6,8,11,13,15(19),16-nonaene, but that doesn't carry quite the same panache.


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The Olympicene story goes something like this - Graham Richards, late of Oxford University and council member of the Royal Society of Chemistry (RSC), talked with Antony Williams, Fellow of the RSC (FRSC), about the possibilities of the five ringed compound. Williams later spoke with Peter Scott (Professor of Chemistry at the University of Warwick, and FRSC) about the Olympic rings. They were (and are) involved in pushing the mission of the ChemSpider Synthetic Pages (an open-source database of practical synthetic procedures).

In response to this Olympic challenge, they announced a competition for the most elegant synthesis and the simplest synthesis for the five ring compound. Very little interest was expressed, but David Fox (Associate Professor of Chemistry at the University of Warwick) agreed to attempt a synthesis, together with Anish Mistry, a researcher in Fox's group. They used clever applications of relatively standard methods to successfully make what was to be called Olympicene.

Sample of olympicene powder - the pure powder is white, but degrades with exposure to light

"Alongside the scientific challenge involved in creating olympicene in a laboratory, there's some serious practical reasons for working with molecules like this," said Prof. Fox. The compound is related to single-layer graphite, also known as graphene, and is one of a number of related compounds which potentially have interesting electronic and optical properties."

There was still one part of the project to be accomplished - imaging the molecule. Scanning electron microscopy was not capable of resolving individual atoms in a 1.2 nanometer wide molecule (that's around 100,000 times thinner than a human hair). Fox and Mistry did see some structure using a scanning tunneling microscope, but the resolution was still inadequate for the purpose.

In response, they made contact with Dr. Leo Gross, of IBM-Zurich. Dr. Gross is among the world's few experts on noncontact atomic force microscopy, an imaging technique that measures the interaction between electrons on a scanning probe with electrons in a molecule. This technique, when carried out by a single carbon monoxide molecule attached to the scanning tip, detects the strength of the short-range chemical forces - the bonds between the atoms. In 2009, his team was the first to image the structure of an isolated organic molecule, pentacene. (As an aside, pentacene also has five benzene rings, but in a linear structure.)

Dr. Gross and his colleagues at IBM Research-Zurich, in collaboration with Assoc. Prof. of Chemistry Giovanni Constantini of the University of Warwick, succeeded in imaging the olympicene molecule with remarkable precision.

The result is not only a tribute to the 2012 Olympics, but also an affirmation of the power of modern synthetic organic chemistry.

Source: Royal Society of Chemistry

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