Controlling the oxidation state of arsenic in cyclic arsenic cations

Reduction of AsCl3 with SnCl2, followed by treatment of the "AsCl" with a 1,4-diimine results in electron transfer and formation of an arsenic(III) salt, while treatment of this arsenic(I) reagent or AsI3 with an alpha,alpha'-diiminopyridine ligand forms an arsenic(I) salt.     

An N,N'-chelated phosphenium cation supported by a beta-diketiminate ligand

The first example of a phosphenium cation supported by N,N'-chelation of a beta-diketiminate ligand has been prepared and structurally characterized.     

Do enzymes sleep and work?

Single-enzyme studies suggest that dynamic disorder is a general characteristic of enzyme catalysis.     

A mechanistic rationalization of unusual kinetic behavior in proline-mediated C-O and C-N bond-forming reactions

Kinetic evidence supports the role of the reaction product in the catalytic cycle of proline-mediated alpha-aminoxylation and alpha-amination reactions, providing both design principles as well as a model for the evolution of efficiency in catalysis.     

X-Ray crystallographic and EPR spectroscopic characterization of a pyrrolidine adduct of Y3N@C80

Crystallographic data for the pyrrolidine adduct Y3N@C80C4H9N x 2.5CS2 reveals a slightly pyramidalized Y3N unit with idealized mirror symmetry that straddles the site of addition but does not directly interact with the addend.     

A high power hybrid mid-IR laser source

An efficient hybrid mid-IR laser system comprising a thulium fibre laser, Ho:YAG solid state laser and a zinc germanium phosphide optical parametric oscillator is presented. A 790 nm diode pumped 1908 nm thulium fibre laser operating at 30 W pumps an RTP q-switched Ho:YAG laser emitting 17 W at 40 kHz and 2090 nm. The zinc germanium phosphide optical parametric oscillator efficiently converts this into the 3-5 μm region producing 10.1 W with 59% optical conversion efficiency and an M² = 1.5.     

Role of sub-surface oxygen in Cu(100) oxidation

Density functional theory (DFT) calculations are used to investigate the role of sub-surface oxygen in Cu(100) oxidation. We find that the presence of sub-surface oxygen atoms causes the top copper layer of the missing-row reconstructed surface to rise by 1.7 Å compared to the bare surface. This prediction compares well to an earlier scanning tunneling microscopy measurement of 1.8 Å [Lampimaki et al. Journal of Chemical Physics 126 (2007) 034703]. When the missing-row reconstructed surface is exposed to an additional oxygen molecule, surface restructuring that leads to oxide-like structures is only observed when sub-surface oxygen is present. The oxide-like nature of these structures is confirmed through structural, Bader, and electron density of states analyses. These findings, combined with our previous DFT results that predicted low energy barriers for the embedment of oxygen atoms into the sub-surface [Lee and McGaughey, Surface Science 603 (2009) 3404], demonstrate the key role played by sub-surface oxygen in Cu(100) oxidation.