Photo-enhanced hydrolysis of bis(4-nitrophenyl) phosphate using Cu(II) bipyridine-capped plasmonic nanoparticles

We show that the hydrolysis of bis(4-nitrophenyl) phosphate by a Cu(II) bipyridine complex was enhanced by 1000-fold when covalently attached to 10 nm gold nanoparticles (AuNP) and irradiated with a 120 mW green laser at 532 nm when compared to an unsupported vinyl-substituted Cu bipyridine analog. The catalytic reaction was monitored by UV-vis spectroscopy in 20 mM MOPS buffer at pH 8 and at room temperature by observing the growth of the product, 4-nitrophenolate, at 405 nm. Initial rate data was analyzed using a Michaelis-Menten formalism. Control experiments suggested that the photo-enhanced hydrolysis reaction required that the Cu metal center be attached to the AuNPs via a thiolated bpy ligand. At higher laser power, the initial rate data deviated from the Michaelis-Menten formalism. Possible mechanisms are discussed.