Chemistry

Site-Specific Catalysis

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Science  16 Sep 2005:
Vol. 309, Issue 5742, pp. 1791
DOI: 10.1126/science.309.5742.1791b

Chemical patterning of surfaces has traditionally been achieved by zapping a reactive coating with light or electron beams. More recently, “dip pen” techniques have used atomic force microscope (AFM) probes to plant molecules in selected surface locations. Davis et al.show that AFM probes can also be used as spatially selective catalysts. They capped the silicon nitride probe tips with palladium nano-particles, which catalyzed the Suzuki coupling of aryl boronic acids to a layer of aryl bromides that were bound through sulfide linkages to a gold surface. After submerging the film in a methanol solution of the boronic acid and a base, they maneuvered the probe to the desired reaction site and induced coupling by applying 20 to 25 nN of force between tip and surface. Reducing the force to the 1- to 5-nN range allowed imaging of the patterned surface without further catalysis. For verification of spatial selectivity, coupling was performed with amine-substituted boronic acid substrates, which were subsequently labeled with fluorescent dye. — JSY

J. Am. Chem. Soc. 10.1021/ja043235+ (2005).

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