Working with his students, Moeller started by running a well-known electrochemical Wacker oxidation reaction, which converts an olefin into a ketone using palladium(II) on selected electrodes on the chip. In order to do this, the palladium(II) reagent needed at a selected electrode was actually made at the desired site using the electrode. This allowed for the desired reaction at only electrodes that were turned on. To keep the palladium(II) from going to a neighboring electrode a second reagent was added to the solution above the chip that destroyed the palladium(II) reagent. In this way, nothing happened at electrodes that were not being used.
Reversing the polarity of things
"The chip is an ongoing battle between active reagent and inactive reagent," Moeller said. "The active reagent is fine ?it does the chemistry I want it to do ?but as soon as it gets away from the turned-on electrode the reaction that inactivates it needs to take over."
With an overall strategy in place, Moeller and his collaborators are working to expand the scope of reactions that can be done. For example, they have carried out the oxidation of an alcohol to form a carbonyl and then used the carbonyl to put a dye down. They placed a green dye at alternating electrodes in a checkerboard pattern, and then used the alternate set of electrodes to put down a red dye. The result was a red and green chip, Washington University's colors. This, Moeller said, is a striking image of the technique's ability to do chemistry at spec
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Source:Washington University in St. Louis