Materials theorist wins Nobel in physics French theorist Pierre-Gilles de Gennes has won the 1991 Nobel Prize in Physics for describing how complex chemical systems such as liquid crystals and polymers behave during the transition from an or­dered to a disordered state. The Roy­al Swedish Academy of Sciences cites him, in addition, for showing that such phase transitions, also seen in magnetic systems and supercon­ductors, can be described in surpris­ingly general mathematical terms.

De Gennes, 59, is a professor at the Collège de France and director of the Ecole de Physique et Chimie, both in Paris.

Some have called him "the Isaac Newton of our time/' in admiration of his perceptive thinking on the

; common threads of order and disor­der in widely differing physical sys­tems. The academy, which awarded the $1 million prize, notes that some systems de Gennes has studied are so complicated that few physicists

. thought they could be incorporated into a general physical description. Physicists often have sought systems as simple and "pure" as possible. But de Gennes has shown that even "un­tidy" systems can be described suc­cessfully in general terms.

"His work, which is theoretical, has had broad implications in both chemistry and physics," comments physical chemist Carl W. Garland of

De Gennes: forging interconnections

Massachusetts Institute of Technolo­gy. Basic research on liquid crystals, and their application in laptop com­puter and digital watch displays, have been influenced by de Gennes' writings. Those writings include a seminal book, "The Physics of Liquid Crystals," which Garland says "is very widely referred to and used." De Gennes also has written books on polymer physics and low-tempera­ture superconductors.

Garland observes that de Gennes has "a very great talent" for seeing connections between apparently dif­ferent problems. For example, this talent allowed de Gennes to discern important similarities in the behav­ior of liquid crystals and inorganic superconductors. And in what phys­ical chemist William M. Gelbart of the University of California, Los An­geles, calls a "mathematical tour de force," de Gennes uncovered formal

The family of carbon-cage molecules known as fullerenes now appears to contain members significantly more complex than the perfectly symmet­rical prototype of the family, C60, and its highly symmetrical first cousin, C70.

Scientists discussing largely un­published research on fullerenes at a meeting of the Electrochemical Soci­ety last week in Phoenix revealed that C78 exists as two separable iso­mers. And evidence is beginning to accumulate that large fullerenes may, in some cases, have a tubular shape rather than a hollow, balloon­like shape.

Perhaps it was inevitable: C60, or buckminsterfullerene, can have only one geometry—that of a truncated icosahedron—that accounts for its properties. For somewhat more com­plex reasons, C70, too, can have but a single symmetrical structure. Most early speculation on the structure of larger fullerenes simply built on this motif.

Now Robert L. Whetten, chemistry professor at the University of Califor­nia, Los Angeles, and his collabora­tors—who include chemistry profes­sor François Diederich—report that C78 separates as two peaks on a high-performance liquid chromatography

similarities between the motions of long polymer chains and a system of magnetic moments undergoing a phase transition. The forging of such interconnections between widely different systems has stimulated new research and new ways of thinking about the results.

Another major contribution of de Gennes—the reptation model—de­scribes the serpentine motion of a polymer chain as it slithers, snake­like, through a tangle of surrounding polymer chains. "That's been the key idea in understanding the dynamics of concentrated polymers, whether they're polymer solutions or polymer melts," Gelbart says.

For his work on polymer behav­ior, de Gennes has won a number of other awards, including the Ameri­can Chemical Society's Award in Polymer Chemistry in 1988.

Ron Dagani

column. The two isomers display dis­tinct optical and 13C nuclear magnet­ic resonance spectra, Whetten says. Recent calculations by David E. Manolopolous of the University of Nottingham, England, indicate that C78 could have five possible fuller-ene structures, and the UCLA 13C NMR spectra show that the isomers do, in fact, possess two of these struc­tures. Furthermore, C84 also appears to form as a mix of isomers, the UCLA researchers have found.

Richard E. Smalley, chemistry professor at Rice University, Hous­ton, and one of the codiscoverers of the fullerenes, described in Phoenix research on fullerenes that encapsu­late lanthanum atoms.

Early research in Smalley's lab demonstrated that laser vaporization of La203-impregnated graphite pro­duces C60 containing a single lantha­num atom, which Smalley designates (La@C60) (C&EN, Sept. 2, page 6). Given the sizes of a lanthanum atom and the cavity of C60, the lanthanum actually "rattles around" inside buck­minsterfullerene, Smalley says. Re­search at Rice has shown that laser photolysis of (La@C60) produces suc­cessively smaller, even-numbered carbon cages containing the lantha­num atom, a series that terminates in

Fullerenes more complex than previously thought

October 21, 1991 C&EN 5