One day, scientists hope, they will be able to sit down at their
computers with a list of requirements—an easily tolerated drug
that targets one specific cancer, say, or an auto panel that’s
tough, light, cheap and completely recyclable—and design a substance
that meets those requirements precisely.
Today’s reality is more prosaic; most useful compounds
are still discovered by old-fashioned trial and error, guided
by the researchers’ knowledge, experience and educated
guesses. Nonetheless, that long-range vision of molecules
and materials "by design" is a lot closer to
fruition than it used to be, thanks to rapid progress in
three areas—all of which are supported strongly by
NSF.
First, scientists are getting a much better understanding
of what’s actually going on inside materials, and in
chemical reactions. Over the past quarter-century, for example,
scientists have been using facilities such as the NSF-funded
Cornell High Energy Synchrotron Source (CHESS)
to probe the structures of molecules and materials with ultra-bright
x-ray light. More recently, scientists have also begun to
probe those structures with slow-moving, "cold" neutrons,
which have found applications in fields ranging from drug
design to corrosion detection in airplane wings. In 2003,
in fact, NSF committed some $6.4 million to Indiana University
to produce cold neutrons at a Low Energy Pulsed Neutron Source
(LENS).
(A much larger facility, the Department of Energy's billion-dollar Spallation
Neutron Source, is scheduled for completion in 2006 at
the Oak Ridge National Laboratory in Tennessee.) And in 1999,
meanwhile, Caltech’s Ahmed Zewail won the Nobel
Prize in chemistry for his pioneering, NSF-funded work
with "femtosecond" lasers—in effect, ultra-fast
strobe lights that allowed him to study the making and breaking
of chemical bonds on timescales of a millionth of a nanosecond.
Second, chemists and materials scientists are making rapid
progress in mathematical theories, computer simulations and
data analysis. Much of their work builds on the theoretical
and computational methods pioneered by John Pople of Northwestern
University and Walter Kohn of the University of California,
Santa Barbara, for which they shared the 1998 Nobel
Prize in chemistry. But new concepts and approaches are
being developed all the time. At Stanford University, for
example, Vijay Pande and his group have made remarkable strides
in simulating the folding (and mis-folding) of protein molecules
through their Folding@home project,
in which the calculations are parceled out across the Internet
and processed on thousands of idle PCs running a special
screen-saver program. And at MIT, Professor Gerbrand Ceder
and research associate Dane Morgan are applying advanced data-mining techniques
to predict the crystalline structure of proteins, alloys
and other new materials.
And finally, since designing a compound does you no good unless
you can also make it, researchers are pushing hard
to develop new molecular building blocks that will help them
do just that. Perhaps the most famous of these building blocks
are the long, thin nanotubes and
the spheroidal fullerene molecules,
a.k.a. "buckyballs"—new forms of carbon that
show great promise in applications ranging from drug delivery
to light-emitting electronic materials for use in flat-screen
televisions. But a wide variety of other molecular modules
are being explored as well, notably by Jean
Fréchet and his team at the University of California,
Berkeley, and by Virgil
Percec and his group at the University of Pennsylvania.
And in the meantime, researchers are coming up with some remarkably
innovative chemical synthesis techniques, such as those being
developed by Krzysztof
Matyjaszewski and his group at Carnegie Mellon University.
Creating New Kinds of Materials
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