Comment

Trevor Keel and Graham Hutchings celebrate a partnership that rarely gets a mention

When you ask someone what comes into their mind when you say the word ’gold’, the responses you receive rarely offer any surprise. Jewellery is probably at the forefront of most people’s mind, along with various examples of gold’s role in the world of finance. Words such as ’science’, ’technology’ and (most definitely) ’chemistry’ rarely get a mention. This, perhaps, is not a surprise. To most people’s mind gold is eternal - the ultimate preserver of wealth, a constant typified by the jewellery many of us wear often throughout our entire lives. Physical sciences such as chemistry on the other hand are all about change - manipulating the elements to generate useful materials. How could gold play a role in chemistry?

Gold in science 

Of course many of you reading this article will know something of gold’s place within the sciences. There are a number of ancient, yet well documented, examples of the metal’s unique properties. For example the Lycurgus Cup, now over 1400 years old, is coloured with colloidal gold and silver (an early example of nanotechnology, albeit an unwitting one). In the seventh century BC the Etruscan peoples used gold wire to secure substitute teeth, understanding that the metal was both malleable and would not degrade in the mouth.  

But it is more recent examples that directly link the metal to the physical sciences in a traditional, scientific sense. Michael Faraday’s 1857 report¹ conjectured (correctly) that gold could exist in solution as a ’finely divided metallic state’ rather than as an oxide, and exactly 100 years ago the Nobel prize winner Ernest Rutherford published data from what became known as the ’gold foil’ experiments.² This study, carried out by Hans Geiger and Ernest Marsden under Rutherford’s direction at the University of Manchester, UK, involved directing a beam of alpha particles at a very thin film of gold, and measuring deflection of those particles. Of course, the resulting data eventually led to definitive proof of the existence of the nucleus and hence structure of the atom.  

Recent breakthroughs 

Since the pioneering studies of Faraday and Rutherford, gold has become increasingly important in science and technology generally. The 1960s saw two major breakthroughs - firstly, work at Bell Laboratories, Murray Hill, US, led to the development of the first gold-bonded microchips. This was quickly followed by Nasa’s use of gold to protect sensitive instruments from radiation in space. These applications highlight bulk gold’s unique properties: malleability, corrosion resistance and excellent electrical conductance. However, it was the 1970s and 1980s that saw gold and chemistry become increasingly synonymous through pioneering work in the field of catalysis. A handful of studies, most notably those of Geoff Bond and colleagues,³ were published throughout the 1970s which described gold having some catalytic activity in certain reactions, albeit less so than other metals. It was not until the 1980s that gold was shown to be the superior catalyst, both theoretically and experimentally, in a range of reactions including acetylene hydrochlorination⁴ and CO oxidation⁵. Much of this work coincided with a growing interest in the chemistry of gold-based compounds for the generation of new materials and medicines. Famously, one of these compounds was successfully brought to market by Smith Kline & French (now part of GlaxoSmithKline) as a treatment for rheumatoid arthritis.⁶ Most recently it has been nanotechnology that has benefitted from gold’s unique properties, with numerous breakthroughs in a range of fields reliant on the metal’s functionality and reliability on the nanoscale.  

Celebrating gold   

The growth in the use of gold in catalysis, chemistry and nanotechnology has been phenomenal - there really is no other way it can be described. In the period 2001-10, the word ’gold’ or the symbol ’Au’ appeared in the title or abstract of over 2500 Royal Society of Chemistry book or journal articles. 2010 alone made up 669 of these, further illustrating the importance of the metal in present day cutting-edge research.  

To help celebrate gold’s role in science and technology in the International Year of Chemistry, the World Gold Council and the RSC have teamed up to develop a unique microsite⁷offering free access to some of the RSC’s best gold-related publications until the end of 2011. There is a spread of historical and cutting-edge papers, spanning catalysis, chemistry, nanotechnology and novel materials. We hope you enjoy the collection.

Trevor Keel is project manager at the World Gold Council; Graham Hutchings is professor of physical chemistry at the University of Cardiff, UK