Randy L. Lawrence, Billy Scola, Yue Li, Chang-Keun Lim, Yang Liu, Paras N. Prasad, Mark T. Swihart, Marc R. Knecht

We introduce here a concept of remote photoinitiated reconfiguration of ligands adsorbed onto a nanocatalyst surface to enable reversible modulation of the catalytic activity. This is demonstrated by using peptide ligand-capped Au nanoparticles with a photoswitchable azobenzene unit integrated into the biomolecular ligand. Optical switching of the azobenzene isomerization state drives rearrangement of the ligand layer, substantially changing the accessibility and subsequent catalytic activity of the underlying metal surface. The catalytic activity was probed using 4-nitrophenol reduc-tion as a model reaction, where the position of the photoswitch in the peptide sequence and its isomerization state both affected the catalytic activity of the nanoparticles. Reversible switching of the isomerization state produces reversible changes in catalytic activity via reconfiguration of the biomolecular overlayer. These results provide a pathway to catalytic materials whose activity can be remotely modulated, which could be important for multistep chemical transformations that can be accessed via nanoparticle-based catalytic systems.