Conservation of angular momentum is a fundamental property of nature,
one that astronomers use to detect the presence of satellites circling
distant planets. In 1927, it was proposed that this principle should
apply to chemical reactions, but a clear demonstration has never been
achieved.
MSU chemist Jim McCusker and postdoctoral researcher Dong Guo proved an 84-year-old theory.
In the current issue of Science, MSU chemist Jim McCusker
demonstrates for the first time the effect is real and also suggests how
scientists could use it to control and predict chemical reaction
pathways in general.
"The idea has floated around for decades and has been implicitly
invoked in a variety of contexts, but no one had ever come up with a
chemical system that could demonstrate whether or not the underlying
concept was valid," McCusker said. "Our result not only validates the
idea, but it really allows us to start thinking about chemical reactions
from an entirely different perspective."
The experiment involved the preparation of two closely related
molecules that were specifically designed to undergo a chemical reaction
known as fluorescence resonance energy transfer, or FRET. Upon
absorption of light, the system is predisposed to transfer that energy
from one part of the molecule to another.
McCusker's team changed the identity of one of the atoms in the
molecule from chromium to cobalt. This altered the molecule's properties
and shut down the reaction. The absence of any detectable energy
transfer in the cobalt-containing compound confirmed the hypothesis.
"What we have successfully conducted is a proof-of-principle
experiment," McCusker said. "One can easily imagine employing these
ideas to other chemical processes, and we're actually exploring some of
these avenues in my group right now."
The researchers believe their results could impact a variety of
fields including molecular electronics, biology and energy science
through the development of new types of chemical reactions.
Dong Guo, a postdoctoral researcher, and Troy Knight, former graduate
student and now research scientist at Dow Chemical, were part of
McCusker's team. Funding was provided by the National Science
Foundation.
From sciencedaily
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