Computer-designed molecule to clean up fluo...( The chemical bond between carbon and f...)

The chemical bond between carbon and fluorine is one of the strongest in nature, and has been both a blessing and a curse in the complex history of fluorocarbons. Now, in a powerful demonstration of the relatively new field of "computational chemistry," researchers at the National Institute of Standards and Technology (NIST) and the Interdisciplinary Network of Emerging Science and Technology group (INEST, sponsored by Philip Morris USA) have designedin a computera wholly theoretical molecule to pull the fluorine out of fluorocarbons.*

At sea level, the strong C-F bond makes fluorocarbons thermally and chemically stable. As a result, fluorocarbons have been used in many commercial applications including refrigerants, pesticides and non-stick coatings. In the upper atmosphere, however, high-energy photons and highly reactive ozone molecules can break apart fluorocarbons, with the well-known consequence of a depleted ozone layer and increased ultraviolet radiation at ground level. A determined chemist can break down fluorocarbons at ground level with certain organometallic compounds, but the reactions take a long time at very high temperatures. Other known reagents are both highly toxic and inefficient, so chemists have been searching for an economical and environmentally friendly method to dispose of fluorocarbons.

Reasoning that the problem already may have been solved by nature, the NIST/Philip Morris team looked to an enzyme called fluoroacetate dehalogenase used by a South African bacterium, Burkholderia sp. The enzyme enables the bacterium to pull the fluoride ion out of sodium fluoroacetate (disrupting a poisonous compound) at room temperature and without problematic metal ions. Enzymes are giant molecules, evolved to survive and work in the complex environment of a living organism; they can be difficult and expensive to adapt to an industrial process. Instead, the research team applied basic quantum mechanical theory of electron structur
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Contact: Michael Baum
michael.baum@nist.gov
301-975-2763
National Institute of Standards and Technology (NIST)
2-Mar-2007