Surface plasmon resonance promotion of homogeneous catalysis using a gold nanoparticle platform

Reaction of 10 nm gold nanoparticles (AuNPs) with a thiol-functionalized bipyridine copper(II) complex, Cu[( N -(6-mercaptohexyl)-2,2′-bipyridinyl-5-carboxamide)]Cl 2 ( 3 ), and (1-mercaptohex-6-yl)tri(ethylene glycol) ( 5 ) in different ratios resulted in mixed monolayer modified NPs with varying surface coverage of capping agent. The copper complex modified NPs were used for surface plasmon resonance (SPR) promoted homogeneous catalysis applied to the hydrolysis of the nerve agent methyl parathion (MeP) at pH 8.0. Low power green laser (532 nm) irradiation of solutions of modified AuNPs with MeP resulted in significant increase in the rate of phosphate ester hydrolysis which could not be attributed to a thermal process. Ratios of initial rates (laser/dark) at high substrate concentrations of MeP as a function of copper catalyst coverage were determined. A possible mechanism for catalytic enhancement involving dissociation of catalytically inactive hydroxy-bridged Cu(II) dimer is discussed.