105 research outputs found
Phase behavior of repulsive polymer-tethered colloids
We report molecular dynamics simulations of a system of repulsive,
polymer-tethered colloidal particles. We use an explicit polymer model to
explore how the length and the behavior of the polymer (ideal or self-avoiding)
affect the ability of the particles to organize into ordered structures when
the system is compressed to moderate volume fractions. We find a variety of
different phases whose origin can be explained in terms of the configurational
entropy of polymers and colloids. Finally, we discuss and compare our results
to those obtained for similar systems using simplified coarse-grained polymer
models, and set the limits of their applicability.Comment: 7 pages, 5 figures. Published in the Journal of Chemical Physic
Phase Equilibria Calculations of Polyethylene Solutions from SAFT-Type Equations of State
Hydrogen-transfer catalysis with Cp*Ir<sup>III</sup> complexes:The influence of the ancillary ligands
Fourteen Cp*IrIII complexes, bearing various combinations of N- and C-spectator ligands, are assayed in hydrogen-transfer catalysis from isopropyl alcohol to acetophenone under various conditions to investigate ligand effects in this widely used reaction. The new cationic complexes bearing monodentate pyridine and N-heterocyclic carbene (NHC) ligands were characterized crystallographically and by variable-temperature nuclear magnetic resonance (VT-NMR). Control experiments and mercury poisoning tests showed that iridium(0) nanoparticles, although active in the reaction, are not responsible for the high activity observed for the most active precatalyst [Cp*Ir(IMe) 2Cl]BF4 (6). For efficient catalysis, it was found necessary to have both NHCs in monodentate form; tying them together in a bis-NHC chelate ligand gave greatly reduced activity. The kinetics of the base-assisted reaction showed induction periods as well as deactivation processes, and H/D scrambling experiments cast some doubt on the classical monohydride mechanism. © 2013 American Chemical Society
Developing asymmetric iron and ruthenium-based cyclone complexes : complex factors influence the asymmetric induction in the transfer hydrogenation of ketones
The preparation of a range of asymmetric iron and ruthenium-cyclone complexes, and their application to the asymmetric reduction of a ketone, are described. The enantioselectivity of ketone reduction is influenced by a single chiral centre in the catalyst, as well as by the planar chirality in the catalyst. This represents the first example of asymmetric ketone reduction using an iron cyclone catalyst
Potassium formate as a small molecule switch: controlling oxidation-reduction behaviour in a two-step sequence
Contains fulltext :
111394.pdf (preprint version ) (Open Access
Chemoenzymatic Dynamic Kinetic Resolution of β-Halo Alcohols. An Efficient Route to Chiral Epoxides
Phosphite‐thioether/selenoether Ligands from Carbohydrates: An Easily Accessible Ligand Library for the Asymmetric Hydrogenation of Functionalized and Unfunctionalized Olefins
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