Professor Alex Jen, Boeing-Johnson Chair professor of materials science and engineering and professor of chemistry, and his co-workers have demonstrated the ability to foster an extremely unlikely chemical reaction between two molecules by tethering them into the correct orientation on a gold surface. The study is reported in the March 11, 2011 issue of Science. The research was also highlighted in the March 14, 2011 issue of Chemical & Engineering News:
“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.”
To learn more about Prof. Jen’s research, visit his group research page.
For more information about the Science article, read the UW press release.