Molecular Dynamics of Polyrotaxane in Solution Investigated by Quasi-Elastic Neutron Scattering and Molecular Dynamics Simulation: Sliding Motion of Rings on Polymer.

In this study, we investigated the molecular dynamics of polyrotaxane (PR), composed of α-cyclodextrins (CDs) and a poly(ethylene glycol) (PEG) axial chain, in solution by means of quasi-elastic neutron scattering (QENS) measurements and full-atomistic molecular dynamics (MD) simulations. From QENS experiments, we estimated the diffusion coefficients of CD and PEG monomers in PR, which are in quantitative agreement with those obtained by MD simulations. By analyzing the simulation results, we succeeded, for the first time, in observing and quantifying the sliding motion of CD along a PEG chain.

Measurement of dipole potential in bilayer lipid membranes by dielectric spectroscopy.

Planar bilayer lipid membranes formed from egg phosphatidylcholine in aqueous media containing the lipophilic anion, dipicrylamine (DPA), were studied by dielectric spectroscopy over a frequency range of 10 Hz-10 MHz. The membranes showed dielectric relaxation due to the translocation of DPA between the membrane interfaces. Incorporating either cholesterol or 6-ketocholestanol into the membranes increased the characteristic frequency of the relaxation, which is proportional to the translocation rate constant of DPA.

Deciphering DNA-based asymmetric catalysis through intramolecular Friedel-Crafts alkylations.

We describe asymmetric intramolecular Friedel-Crafts alkylations with a DNA-based hybrid catalyst and propose a plausible binding model. This study shows promise for studying relationships between the helical chirality of DNA and enantioselectivity of the chemical reaction.