Rafaela Nita

Accelerating the initial rate of hydrolysis of methyl parathion with laser excitation using monolayer protected 10 nm Au nanoparticles capped with a Cu(bpy) catalyst

Using a low power green laser, we have demonstrated a rate acceleration of ~2-fold for the hydrolysis of methyl parathion by irradiating the plasmon absorption band of Au nanoparticles capped with a Cu(bpy) catalyst.

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.

Tunable subnanometer gap plasmonic metasurfaces

The index of refraction governs the flow of light through materials. At visible and near-infrared wavelengths the real part of the refractive index is limited to less than 3 for naturally occurring transparent materials, fundamentally restricting applications. Here, we carried out experiments to study the upper limit of the effective refractive index of self-assembled metasurfaces at visible and near-infrared wavelengths. The centimeter-scale metasurfaces were made of a hexagonally close packed (HCP) monolayer of gold nanospheres coated with tunable alkanethiol ligand shells, controlling the interparticle gap from 2.8 to 0.45 nm. In contrast to isolated dimer studies, the macroscale areas allow for billions of gaps to be simultaneously probed and the HCP symmetry leads to large wavelength shifts in the resonance mode, enabling subnanometer length scale mechanisms to be reproducibly measured in the far-field. We demonstrate for subnanometer gaps that the optical response of the metasurfaces agrees well wit...

Crystal structure of catena-poly[[chlorido­(4,4′-dimethyl-2,2′-bi­pyridine-κ2N,N′)copper(II)]-μ-chlorido]

The structure of a previously unknown form of dichlorido(4,4′-dimethyl-2,2′-bipyridine)copper(II) was obtained via a DMSO-mediated dehydration of Cu(4,4′-dimethyl-2,2′-bipyridine)copper(II)·0.25H2O. The crystal structure reveals chloride-bridged copper(II) chains connected via intermolecular C—H⋯Cl hydrogen bonds.