Skip to Main Content

Latest News

Advertisement
Advertise Here
March 14, 2011
Volume 89, Number 11
p. 12

Poised To React

Nanoscience: Tethering molecules to gold surface forces reaction

Bethany Halford

Close Encounter  A 4 + 4 photocycloaddition of two anthracene analogs occurs when the molecules are tied next to each other on a gold surface.
  • Print this article
  • Email the editor

Latest News



October 28, 2011

Speedy Homemade-Explosive Detector

Forensic Chemistry: A new method could increase the number of explosives detected by airport screeners.

Solar Panel Makers Cry Foul

Trade: U.S. companies complain of market dumping by China.

Novartis To Cut 2,000 Jobs

Layoffs follow similar moves by Amgen, AstraZeneca.

Nations Break Impasse On Waste

Environment: Ban to halt export of hazardous waste to developing world.

New Leader For Lawrence Livermore

Penrose (Parney) Albright will direct DOE national lab.

Hair Reveals Source Of People's Exposure To Mercury

Toxic Exposure: Mercury isotopes in human hair illuminate dietary and industrial sources.

Why The Long Fat?

Cancer Biochemistry: Mass spectrometry follows the metabolism of very long fatty acids in cancer cells.

Text Size A A

Using exquisite control at the nanoscale, researchers have demonstrated that they can foster an extremely unlikely chemical reaction—one that simply would not occur in the bulk. Exercising control over reactivity in this manner “has great potential for both understanding and measuring complex chemical reactions,” the researchers write in Science (DOI: 10.1126/science.1200830).

In the work, chemists led by Paul S. Weiss and Kendall N. Houk of the University of California, Los Angeles, and Alex K-Y. Jen of the University of Washington, Seattle, tied two anthracene analogs next to each other on a gold surface. This forced the molecules to react in a manner that, although theoretically possible in solution, rarely occurs there because of unfavorable geometry.

In principle, the mallet-shaped molecule 9-phenylethynylanthracene (PEA) should undergo a 4 + 4 photocycloaddition with another molecule of PEA. But because of geometric constraints, that reaction rarely happens. Instead, one PEA’s anthracene moiety tends to do Diels-Alder chemistry with the ethynyl unit on another PEA’s phenylethynyl handle.

To force the disfavored reaction, the researchers attach a thiol group to the end of PEA’s handle and tether two such molecules next to one another on a gold surface within the defect sites of a self-assembled alkanethiolate monolayer. The anthracene moieties are then poised in the correct orientation to do the photocycloaddition when photoexcited.

The team used scanning tunneling microscopy to follow the course of the reaction—a feat that took considerable modifications of the microscope. “The most important aspect of this work is to see the effect that photoexcitation has on single molecules in well-defined environments,” Weiss tells C&EN. “We now have a tool to do this.”

The researchers were able to “harness the full power of nanoscale science and engineering toward their ends,” comments Ted Sargent, a nanoscience expert at the University of Toronto.

Chemical & Engineering News
ISSN 0009-2347
Copyright © 2011 American Chemical Society
  • Print this article
  • Email the editor

Services & Tools

ACS Resources

ACS is the leading employment source for recruiting scientific professionals. ACS Careers and C&EN Classifieds provide employers direct access to scientific talent both in print and online. Jobseekers | Employers

» Join ACS

Join more than 161,000 professionals in the chemical sciences world-wide, as a member of the American Chemical Society.
» Join Now!