Catalytic Degradation of Organophosphate Esters Using Gold Nanoparticles, Supported Copper(II) Bipyridine Complexes and Plasmonics

Weapons of mass destruction are often comprised of various types of phosphate esters that mimic critical endogenous biological molecules, thereby blocking essential functions, such as heartbeat. It is, therefore, of utmost importance to design systems that degrade phosphate esters as countermeasure for such chemical and biological weapons. An investigation into the unique properties of gold nanoparticles (AuNPs) has shown that gold surfaces can be used for control of the catalytic hydrolysis of phosphate esters under low-power laser irradiation. Using Michaelis-Menten formalism to determine catalytic rate constants, citrate stabilized gold nanoparticles catalyze the hydrolysis of methyl parathion (MeP) with kcat = 1.8 +/- 0.2 x 10-4 s -1 at pH 8.1. Additionally, the AuNP supported copper(II) complex Cu[(N-(6-mercaptohexyl)-2,2'-bipyridinyl-5-carboxamide)]Cl 2 (1) enhances the activity of MeP by 90-fold ( kcat = 1.2 +/- 0.3 x 10-5 s -1) compared to the unattached Cu(II) bipyridine complex. Laser irradiation (300 mW, 532 nm) of 1/AuNPs results in a 12-fold enhancement for MeP hydrolysis (kcat = 4.3 +/- 2 x 10 -4) and a 1000-fold enhancement for BNPP hydrolysis (k cat = 1.3 +/- 0.06 x 10-4). The ability to influence homogeneous catalytic reactions using plasmonics is an important step towards the development of new catalytic reactions.