Guy Bertrand is a distinguished professor of chemistry at UC Riverside. Credit: L. Duka. |
Chemists
at the University of California, Riverside have accomplished in the lab
what until now was considered impossible: transform a family of
compounds which are acids into bases.
As
our chemistry lab sessions have taught us, acids are substances that
taste sour and react with metals and bases (bases are the chemical
opposite of acids). For example, compounds of the element boron are
acidic while nitrogen and phosphorus compounds are basic.
The
research, reported in the July 29 issue of Science, makes possible a
vast array of chemical reactions – such as those used in the
pharmaceutical and biotechnology industries, manufacturing new
materials, and research academic institutions.
“The
result is totally counterintuitive,” said Guy Bertrand, a distinguished
professor of chemistry, who led the research. “When I presented
preliminary results from this research at a conference recently, the
audience was incredulous, saying this was simply unachievable. But we
have achieved it. We have transformed boron compounds into nitrogen-like
compounds. In other words, we have made acids behave like bases.”
Bertrand’s
lab at UC Riverside specializes on catalysts. A catalyst is a
substance?usually a metal to which ions or compounds are bound?that
facilitates or allows a chemical reaction, but is neither consumed nor
altered by the reaction itself. Crucial to the reaction’s success, a
catalyst is like the car engine enabling an uphill drive. While only
about 30 metals are used to form catalysts, the binding ions or
molecules, called ligands, can number in the millions, allowing for
numerous catalysts. Currently, the majority of these ligands are
nitrogen- or phosphorus-based.
“The
trouble with using phosphorus-based catalysts is that phosphorus is
toxic and it can contaminate the end products,” Bertrand said. “Our work
shows that it is now possible to replace phosphorus ligands in
catalysts with boron ligands. And boron is not toxic. Catalysis research
has advanced in small, incremental steps since the first catalytic
reaction took place in 1902 in France. Our work is a quantum leap in
catalysis research because a vast family of new catalysts can now be
added to the mix. What kind of reactions these new boron-based catalysts
are capable of facilitating is as yet unknown. What is known, though,
is that they are potentially numerous.”
Bertrand
explained that acids cannot be used as ligands to form a catalyst.
Instead, bases must be used. While all boron compounds are acids, his
lab has succeeded in making these compounds behave like bases. His lab
achieved the result by modifying the number of electrons in boron, with
no change to the atom’s nucleus.
“It’s almost like changing one atom into another atom,” Bertrand said.
His research group stumbled upon the idea during one of its regular brainstorming meetings.
“I
encourage my students and postdoctoral researchers to think outside the
box and not be inhibited or intimidated about sharing ideas with the
group,” he said. “The smaller these brainstorming groups are, the freer
the participants feel about bringing new and unconventional ideas to the
table, I have found. About 90 percent of the time, the ideas are
ultimately not useful. But then, about 10 percent of the time we have
something to work with.”
The research was supported by grants to Bertrand from the National Science Foundation and the U.S. Department of Energy.
Bertrand
was joined in the research by Rei Kinjo and Bruno Donnadieu of UCR; and
Mehmet Ali Celik and Gernot Frenking of Philipps-Universitat Marburg,
Germany.
