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Physical chemistry MEHAU KULYK / SCIENCE PHOTO LIBRARY LIBRARY PHOTO SCIENCE / KULYK MEHAU 44 | Chemistry World | August 2010 www.chemistryworld.org Let’s get physical Physical chemists are finding themselves more in demand than ever. Emma Davies finds out why Physical chemistry is entering theory in harmony, he said: ‘with the called Fueling the future, his team something of a golden era. Its overall perspective of contributing In short is using IR spectroscopy to see tools have advanced dramatically accurate, experimentally vetted, The field of physical how protons are accommodated in recent years, so much so that molecular level pictures of reactive chemistry is booming, as in imidazole nanostructures. The scientists from all disciplines are pathways and relevant structures, more and more scientists project is based at the University of entering collaborations with physical physical chemists are in an excellent seek to understand their Massachussetts at Amhurst, US and chemists to gain new insight into position to engage chemistry in work on a molecular level teams are currently working on fuel their specialist subject areas. There is all of its complexity.’ He believes Developing alternative cells containing alternatives to nafion, however some worry that the subject that understanding processes at a energy sources is one a fluoropolymer-copolymer which is could become a victim of its own molecular level is crucial to making area benefiting from a good proton conductor but fails in success, with fundamental research grand scientific leaps forward. a physical chemistry meeting contemporary demand for losing out in the funding stakes to Johnson and his team are working approach high temperature operation. applied science. to understand water’s proton Physical chemistry is The Yale researchers are also using When it comes to applications, chemistry at a molecular level. The now routinely crossing their spectroscopic tools to help using physical chemistry for researchers use gas chromatography- life science boundaries design new catalysts. ‘It’s old school: alternative energy projects can mass spectrometry (GC-MS) with an Obtaining funding Arrhenius [acids forming hydrogen bring in substantial funding. Mark added infrared (IR) capability, which can be problematic, as ions in aqueous solutions] and what Johnson from Yale University, US, gives good structural information. experimental physical is really going on in an aqueous works on one such solar cell project, Working at cryogenic temperatures chemistry is inherently solution,’ says Johnson. ‘I love that drawing on years of spectroscopy- in a rare gas atmosphere, Johnson’s expensive stuff.’ based research into protons in water team can freeze small numbers of Such fundamental science really systems. ‘Physical chemistry is having water molecules (as few as 10 at a fires Johnson. He is aware of a global a renaissance,’ he says. Experimental time) and study the resulting ‘crystal’ move away from funding fundamental and theoretical tools that have taken structures. ‘Very cold ions are nice science but is not overly concerned. decades to yield reliable results are objects. We’re not dealing with floppy Fundamental science has long been finally finding use, he explains. systems at room temperature which ‘directed’, he says, and certainly Today’s physical chemistry pulls are hard to characterise,’ he says. was in his field when he started out together experimental and theoretical over 30 years ago. ‘It’s always up to methods to produce complex model Proton push leaders in the field to nurture the systems which aim to reproduce real Johnson’s fundamental research has basic fundamentals while pointing chemical processes and reveal what found several applications, one of the whole ship towards some possible is happening at a molecular level, says which is fuel cell development. As application,’ he says. Johnson. In a 2009 Nature Chemistry part of a major US National Science This is exactly what Eckart Ruehl, paper entitled Experiment and Foundation-sponsored collaboration professor of physical chemistry at the www.chemistryworld.org Chemistry World | August 2010 | 45 Physical chemistry Free University of Berlin, Germany, isolation, de Vries and his team have does. His research contains both effectively taken biology out of the fundamental and applied elements. equation. ‘We’re finding properties Ruehl uses spectroscopy to study from the time when there was no nanoparticles, looking for example at biology,’ he says. how they penetrate the skin. He also They are looking at the studies properties of single aerosol mechanisms by which the molecules droplets, how pesticides stick to diffuse damaging UV radiation. ‘The particles and what their fate is in the DNA bases can get rid of energy environment. in a very efficient manner, which ‘I like fundamental research yet if I we’re beginning to understand. We were to focus solely on such research think that this may have helped NICOLLE RAGER FULLER / NATIONAL SCIENCE FOUNDATION SCIENCE NATIONAL / FULLER RAGER NICOLLE I would have far fewer collaborators,’ them on early Earth before the he says. He is somewhat disheartened ozone layer formed,’ says de Vries. by today’s move towards applied The researchers are now looking at research, which is partly due to molecules other than DNA’s nuclear changes in societal expectations, he bases – guanine, cytosine, adenine says. ‘When I was a student people and thymine – to help understand worked on very academic and why Nature chose these bases. ‘We’re fundamental projects and now people also beginning to study these things ask: “what is it good for?”’ at femtosecond timescales, trying to ‘Progress comes from fundamental actually observe them in real time and understanding and if people go too to understand at a molecular level fast into applied research, there is a the self-healing process against UV,’ danger that innovation is limited if explains de Vries. people become too tied to possible Vasilios Stavros, a chemist at the practical results,’ Ruehl warns. University of Warwick, UK, is also In May 2010 he attended the focused on the question of why German Bunsen Society of Physical Nature selected these particular Chemistry’s annual meeting. The molecular building blocks. In work conference programme clearly shows that complements that of de Vries, he how applied research is becoming chemistry from the materials science Mark Johnson is is looking at how biological molecules ‘more powerful and accepted,’ he and nanotechnology that ‘everyone is studying proton behave under UV radiation. says. The subtitle of the Bunsen talking about’. Much nanotechnology behaviour in water at a Stavros is co-organising (with conference, Out of the vacuum – and materials science is very applied, fundamental level fellow physical chemist Giovanni through the liquid – into the cell, veering away from classical physical Costantini) the 2010 conference illustrates how physical chemistry is chemistry’s ‘reductionist approach’, for Recent appointees in physical now routinely crossing life science which looks at more fundamental chemistry in Warwick, UK, from 6–8 boundaries. The message is that properties and ‘what makes Nature September. This will offer help and complex physical chemistry at tick,’ he says. encouragement to those embarking solid–gas and solid–liquid interfaces By this reasoning, de Vries could on the funding trail. Talks will is important to help understand himself be described as a classical cover subjects such as how to write transport mechanisms of molecules physical chemist. He uses double into and out of biological cells. resonance spectroscopy to estimate Mike Ashfold is working Such interfacial chemistry is also how DNA bases behaved under the towards a reliable vital for solar cell development. short wavelengths of ultraviolet way to make diamond Organic and polymeric solar cells (UV) radiation at the time of the semiconductors are typically made of organic dye origin of life. His team has discovered molecules grafted to the surface of an that the Watson–Crick bases that oxide material and physical chemists make up our DNA appear to have are well equipped to analyse what unique photochemical properties, happens when a photon is adsorbed giving them a special stability. ‘It’s by the dye molecules and the energy something we had no clue we would transferred to the oxide material. stumble upon when we started Ruehl is organising next year’s looking,’ says de Vries. The study Bunsen meeting. He predicts a came about almost by chance when focus on ultrafast processes such he was using molecular beams to as femtochemistry. ‘There is a bias study species in the vapour phase, but towards control of ultrafast processes limited to analysing small, isolated, and everything you can do with molecules. ‘We had the idea that if we ultrafast lasers,’ he says. ‘People don’t could make larger molecules fly then want to only be spectators – they want we could look at other, more complex to actively change things.’ systems such as DNA bases.’ They managed to overcome the problems Physical nature thrown up by the low vapour pressure Mattanjah de Vries, professor of of the DNA bases and the fact that physical chemistry at the University they tend to decompose when heated. of California, Santa Barbara, US, By transferring the biomolecules into tentatively separates physical the gas phase and studying them in 46 | Chemistry World | August 2010 www.chemistryworld.org a successful grant application. At past meetings, physical chemists have gained courage by sharing their concerns, particularly over grant chasing. One of the people talking at the Warwick meeting is Mike Ashfold, professor of physical chemistry at the University of Bristol, UK, and current president of the RSC’s Faraday division. ‘One problem that experimental physical chemistry has is that it is inherently expensive,’ says Ashfold. ‘The research that I do involves reasonably high vacuum, lots of lasers, and a range of reactors for exploring molecular photochemistry, thin film deposition and for growing diamond. Such sophisticated and specialised equipment makes this kind of physical chemistry expensive,’ he says.

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