Cutting edge chemistry in 2009

Later in the year, a team at Kharkov Institute for Physics and Technology, Ukraine, gave the first ever glimpse of atomic orbitals. Using field-emission electron microscopy, they were able to directly image the electron density surrounding a carbon atom - unveiling the shapes of both s- and p-like orbitals (CW October, p4).¹⁰ 

US scientists demonstrated the remarkable power of magnetic resonance imaging (MRI) by adapting it to create 3D nanoscale pictures of a tobacco mosaic virus. The group, led by Daniel Rugar at IBM’s Almaden Research Center in California, hope their technique will eventually allow researchers to analyse the 3D structure of large biological molecules at atomic resolution without damaging them (CW February, p28).¹¹ 

Peering more closely at the world around us revealed some surprises, such as finding pentagonal ice. Javier Carrasco at the Fritz-Haber Institute of the Max Planck Society in Berlin, Germany, found that water molecules arrange in a pentagonal manner on a copper surface - crushing previous beliefs that the crystal structure of bulk ice is always hexagonal.¹² 

An extraordinary allotrope of elemental boron was uncovered by Artem Oganov at Stony Brook University, New York, and team. This new form, containing B2 and B12 clusters, was particularly surprising because it is held together by ionic bonds (CW March, p5).¹³ 

Additionally, the first video evidence that carbon nanotubes turn as they grow was obtained. Using field emission spectroscopy, Stephen Purcell’s group at the University of Lyon 1, France, showed that carbon atoms add in a regular pattern to the tip of a rotating tube (CW September, p26).¹⁴ 

Catalysing basic knowledge A number of significant fundamental insights into catalytic processes were seen during 2009. This included work by Tobias Ritter and David Powers from Harvard University that boosted our understanding of widely used palladium catalysts - showing for the first time that palladium(III) complexes can take part in the formation of carbon-heteroatom bonds. Previously, only Pd(II) and Pd(IV) complexes were though to be involved (CW July, p29).¹⁵ 

Stephen Buchwald at the Massachusetts Institute of Technology and Carsten Bolm at Aachen University in Germany spent the year playing a game of ’which metal is catalysing your reaction’. In 2007 Bolm announced the first copper-free iron-catalysed cross-coupling reaction, but investigations by Buchwald in 2009 showed that tiny amounts of copper impurities in the iron catalyst have been catalysing the reactions all along (CW August, p4).¹⁶ 

The size and shape of nanocatalysts was under the microscope again, with two groups devising routes to controlling the shape of smaller particles than ever before. Matthias Ballauff and team, at the University of Bayreuth in Germany, developed a method for creating 2-5nm platinum crystals with well defined surfaces.¹⁷ 

In a separate study Francisco Zaera at the University of California, Riverside, made tetrahedral crystals of a similar size and used them in cis-trans isomerisation reactions (CW March, p29).¹⁸ 

The Copenhagen effect 

Climate change and green energy has dominated the headlines during 2009, thanks to the UN Climate Change Conference held in Copenhagen, Denmark, in December. There were a number of unexpected revelations about how chemicals in our atmosphere are effecting climate change, including the scary discovery by Kimberly and Ryan Prather, from the University of California, San Diego, that sulfate and nitrate particles previously thought to help combat global warming (because they reflect sunlight), when combined with soot could instead enhance global warming (CW August, p4).¹⁹ 

Additionally, Akkihebbal Ravishankara’s team at the National Oceanic and Atmospheric Administration in Boulder found that nitrous oxide is currently the most important manmade substance reducing atmospheric ozone. The impact of this chemical has previously been overlooked (CW October, p4).²⁰ 

In the energy area, there has been ongoing progress in research using sunlight to split water - generating hydrogen and oxygen. One potential breakthrough was a new system that doesn’t need rare noble metals, developed by Richard Eisenberg and colleagues at the University of Rochester. Their system used a molecular photocatalyst containing cheap and abundant cobalt.²¹ 

The efficiency of dye-sensitised solar cells (DSSC) crept up again during the year. In an alternative approach, a team led by Licheng Sun at the Royal Institute of Technology at Stockholm, Sweden, suggested that a DSSC with a photoactive anode could be combined with a photoactive cathode-type cell to make a tandem DSSC that would in theory be twice as efficient (CW  June, p4).²² 

Another interesting development was the growing realisation, pioneered by Dan Nocera at Massachusetts Institute of Technology, that instead of improving the efficiency of solar devices, researchers should instead be developing cheaper technology to allow widespread implementation. The green chemistry arena saw an increasing number of novel routes to convert waste into useful products. Examples include an efficient electrochemical method to turn urine into hydrogen fuel, developed by Gerardine Botte of Ohio University (CW August, p25),²³ and super-efficient catalysts for converting waste carbon dioxide emitted from power stations into cyclic carbonate molecules, devised by Michael North’s team at the University of Newcastle (CW December, p29).²⁴

It’s electrifying 

Graphene, the single atom thick layer of carbon, hogged the spotlight yet again in 2009. One fascinating finding was that electrical conducting graphene can be reversibly hydrogenated to electrically insulating graphane, using atomic hydrogen. Daniel Elias’s team, at the University of Manchester, hope their technique will boost the prospects of graphene-based nanoelectronics (CW March, p23).²⁵