A load of bowls
Goverdhan
Mehta and Srirama Sarma at the Indian Institute of Science, in Bangalore are
trying to build a buckyball from scratch. Rather than using the standard
carbon discharge techniques they hope to be able to synthesise the
soccer-ball shaped
molecules from simpler carbon units so they can control the inclusion of
functional groups in a far more specific way than the simple substitution or
addition of groups to the fullerene surface.
Mehta and Sarma have now developed a simple route to the bowl-shaped
fragments benzocorannulenes, which provide a recognised starting point for
fullerene synthesis. They begin with the polyaromatic organic compound
13-methylbenzochrysene, which is readily available from
9-methyl-phenanthrene. The use of FVP (flash vacuum pyrolysis) leads to the
sequential formation of five- and six-membered rings to build up the
buckybowls. 'Our strategy is not only quite general but conceptually so
simple that it should be possible to adapt it for the synthesis of the
buckyball itself,' says Mehta. The team is continuing efforts in that
direction. (Chemical Communications, 2000, 19)
BN, BN
Tough,
tiny cages of boron nitride can trap silver particles according to Japanese
researchers who say the capsules could be used as ball bearings in
nanotechnology devices of the future, components in high-density
optical-magnetic memory devices, catalysis, biotechnology and single
electronic transistors. Takeo Oku and colleagues at Osaka University have
devised a method that works at 700 Celsius to encapsulate metal ions in
spherical capsules of boron nitride. They can easily mass produce (up to a
gram) cheaply. The team simply mixes urea and boric acid in water with
silver nitrate dissolved in deionised water. Evaporating off the solvent
leaves a dry material, which can be annealed by heating in hydrogen for 7
hours. This reduces the BN to a stiff cage-like framework in which the
silver particles are trapped. The team could see their tiny BN balls using
high-resolution electron microscopy and see their structure with energy
dispersive spectroscopy. (Journal of Materials Chemistry, 2000, 255)
Resistance isn't futile
Medicinal
chemists may be partly to blame for the rise of antibacterial resistance to
antibiotics because no new classes have been developed since the 1960s, at
least that is the implications of a recent paper in the British Medical
Journal. According to medical microbiologist Sebastion Amyes of the
University of Edinburgh, it has taken a long time to determine the extent of
the problem and we still have a lot to learn about the way bacteria develop
resistance to antibiotics. Almost all the drugs launched since the 1960s
have been modifications of antibiotics developed up to 1961, explains Amyes,
which means bacteria that evolved resistance to one generic antibiotic type
did not have much to learn to overcome its chemical descendants. Increased
knowledge through genomics and molecular biology, however, will ultimately
provide chemists with new strategies with which to design chemical weapons
for the bug war. (British Medical Journal, 2000, 320, 199) sciencebase
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