Frontier molecular orbital effects control the hole-catalyzed racemization of atropisomeric biaryls.

Atropisomeric biaryl systems are privileged architectures used in asymmetric synthesis and pharmaceutical structures. We report that by simply removing a single-electron, the resistance of biaryls towards racemization is reduced dramatically. Even though the steric properties are unaltered, biaryl oxidation changes atropisomerization into a two step mechanism with considerably smaller activation barriers than closed-shell biaryls.

Dynamic Intermediates in the Radical Cation Diels-Alder Cycloaddition: Lifetime and Suprafacial Stereoselectivity.

Cation radical Diels-Alder cycloadditions proceed via an acyclic intermediate that exists on a flat region of the potential energy surface. Competition between cyclization and C-C bond rotation results in varying levels of suprafacial stereoselectivity. Quasi-classical trajectories were used to explore reaction dynamics on this surface.

Interfacial Properties and Monolayer Collapse of Alkyl Benzenesulfonate Surfactant Monolayers at the Decane-Water Interface from Molecular Dynamics Simulations.

The molecular structure of a surfactant molecule is known to have a great effect on the interfacial properties and the type of nanostructures formed. In this work, we have performed molecular dynamics simulations on six isomers of an alkyl benzenesulfonate surfactant to investigate the effect of the degree and position of aromatic substitution on the interfacial properties and on the collapse of the surfactant monolayer at a decane-water interface. The surface pressure of the monolayers was shown to increase with increasing surface coverage, until some of the monolayers become mechanically unstable and form large undulations.