Enantioselective construction of C-chiral allylic sulfilimines via the iridium-catalyzed allylic amination with S,S-diphenylsulfilimine: asymmetric synthesis of primary allylic amines

We have devised a highly regio- and enantioselective iridium-catalyzed allylic amination reaction with the sulfur-stabilized aza-ylide, S,S-diphenylsulfilimine. This process provides a robust and scalable method for the construction of aryl-, alkyl- and alkenyl-substituted C-chiral allylic sulfilimines, which are important functional groups for organic synthesis. Additionally, the combination of the allylic amination with an in situ deprotection of the sulfilimine constitutes a convenient one-pot protocol for the construction of chiral nonracemic primary allylic amines.     

Physico-chemical characterisation of a new polymorph of caffeine

Caffeine is a widely used drug substance. Two polymorphic forms and one hydrate of caffeine are known. Thanks to scanning transitiometry, the curves pressure versus temperature, P = f(T), of the caffeine were plotted. A (temperature, pressure) unary phase diagram was deduced. It confirms the existence of a new polymorph of caffeine at low pressure synthesized by sublimation. Its identification and its physico-chemical properties were determined using a variety of experimental methods: X-ray powder diffraction, differential scanning calorimeter, thermogravimetric analysis, thermally stimulated current and electrochemical impedance.     

Graph limits of random graphs from a subset of connected k‐trees

For any set Ω of non‐negative integers such that , we consider a random Ω‐k‐tree G_n,k that is uniformly selected from all connected k‐trees of (n + k) vertices such that the number of (k + 1)‐cliques that contain any fixed k‐clique belongs to Ω. We prove that G_n,k, scaled by where H_k is the kth harmonic number and σ_Ω > 0, converges to the continuum random tree . Furthermore, we prove local convergence of the random Ω‐k‐tree to an infinite but locally finite random Ω‐k‐tree G_∞,k.     

Glycolipids from natural sources: dry liquid crystal properties,hydrogen bonding and molecular mobility of Palm Kernel oil mannosides

ABSTRACT

Glycolipids prepared from palm kernel oil, PKO, in tropical regions represent an excellent opportunity to develop new surfactant formulations for cosmeceutical and pharmaceutical applications while contributing to sustainable economies. Here we report the synthesis of a new mannoside obtained from palm kernel oil, aManPKO, and we characterise its thermotropic properties by using DSC, POM, SAXS, WAXS, FT-IR and broadband dielectric spectroscopy. aManPKO exhibits a monotropic smectic phase with a partially interdigitated bilayer structure, similar to its major unsaturated component, the oleyl mannoside with a C18:1 monounsaturated alkyl chain. The smectic phase of aManPKO vitrifies below room temperature, which is associated to the C18:1 component, but also to the activation of short-range motions, ~4 Å, by cleavage of strong hydrogen bonding between the polar heads of the mannosides. The stability of the liquid crystal phase, on the other hand, is linked to the presence of weak hydrogen bonding, whose breakage leads to the activation of long rate motions in the range of the layer distances, ~39 Å.     

Robust Self‐Assembled Monolayers of RuII and OsII Polypyridines on Gold Surfaces: Exploring New Potentials

Functional monolayers : Ru^II and Os^II bis‐terpyridine complexes have been attached through a piperazine‐supported dithiocarbamate to a gold substrate (see picture). The robust tether, and the favourable reduction in oxidation potential induced by the electron‐rich piperazine result in self‐assembled monolayers with excellent reversible redox behaviour and exceptional stability.

     

Towards the evolution of social structure

To what extent can social structure result from evolutionary processes as popposed to being deliberately organised? To begin to answer this questions five different but releated social simulations are reviewed, and a map of which mechanisms might results in what structures under what conditions being started. These show that different structures can be brought about by evolutionary processes based on the abilities and propensities of the individuals. The article ends with some challenges—to construct a credible simulations of more sophisticated structures: social group selection and self-organised value chains.