ChemWeb Newsletter

Not a subscriber? Join now.April 25, 2006


Slicing up carbon to make a new class of electronics, caught The Alchemist's eye first this week, and then a new class of antibiotics that slices up bacteria came to light. In this issue, we also learn how layered ceramics could build three-dimensional nano-devices and that cars produce too much carbon dioxide for environmental targets. Finally this week, designer zeolites could soon be with us thanks to a new model of the crystal growth process.

Car manufacturers are failing the environment in terms of cutting emissions, claim UK researchers who have analyzed RL Polk Marketing Systems data. The research carried out for the European Federation for Transport and Environment (T&E) reveals that the car industry is very unlikely to meet targets for carbon dioxide reduction by 2008. In 1998, the European Automobile Manufacturers Association promised it could deliver new cars that would release just 140 grams per kilometre by this year. New cars in 2005 averaged 160 g/km, which is a mere 1% down on 2004 figures. A 4.3% annual reduction from now until 2008 is needed to hit the target, but T&E director Jos Dings says the European Commission has "sat back and watched while carmakers put all their technology into making cars heavier and more powerful, rather than more fuel efficient," thus allowing them to default on their promises.

New life could be breathed into those stalwarts of filtering, the zeolites, thanks to University of Minnesota chemical engineer Michael Tsapatsis and his colleagues. Zeolites are commonly used in aquarium filters and as ion-exchange agents in laundry detergents. However, their economic impact is much wider as they are the key to cracking new petroleum products on an industrial scale. Tsapatisis and his colleagues have the past year monitoring the growth of zeolites in a laboratory setting to give them a clearer picture of the crystallization process. Their studies will ultimately allow them to develop, validate and improve a quantitative mathematical model describe such complex systems with a view to creating designer zeolites and related materials with highly specific and so efficient catalytic properties.

Andre Geim of the University of Manchester and his colleagues reckon that a novel form of graphite, made by separating out the carbon allotrope's grapheme layers, could form the basis of a new generation of microelectronic devices. Carbon nanotubes are essentially curled up graphene layers, but Geim believes the secret to using graphene is not to roll it up but to lay it out flat. In this form grapheme behaves more like a strange kind of metal than a carbon sheet and its properties are dictated by quantum mechanics. As such, Geim's team has already fashioned graphene sheets into a so-called spin valve. A device that exploits both the charge and the spin of an electron. Such a spintronic valve could be used as a filter for controlling electron flow.

A new way to test antimicrobial compounds that selectively lyse bacterial cell membranes could lead to new topical or intravenous antibiotics and to self-sterilizing countertops and surgical gowns, according to researchers at the University of Massachusetts Amherst. Gregory Tew and his colleagues report details of the approach, which involves x-ray crystal structures and computer calculations, on April 21 in Chemistry & Biology. The work builds on earlier results from Tew’s lab and from colleague Zhan Chen at the University of Michigan. The team has demonstrated the efficacy of their approach on a new synthetic compound designed by Tew's team. “Being able to see how these molecules interact with the membrane at the molecular level in real-time will prove invaluable,” says Tew. "This will let us build much better models of how these novel antibiotics interact with membranes—if we understand that, we can build drugs that are more effective and less toxic," he says.

Scientists at University College London, the Swiss Federal Institute of Technology in Zurich, the University of Tokyo and Lucent Technologies, USA, have unravelled the properties of a novel manganese oxide ceramic and found that it could point the way to creating layered nanotech devices. Team member Gabriel Aeppli explains how the collaborators have overcome one the major problems associated with nanoscopic layered devices - electron leakage between layers. Currently, making ever smaller and more powerful devices relies on two-dimensional integrated circuits, but this discovery opens up a new realm of opportunity for building three-dimensional structures.