Carbon-13 nuclear magnetic resonance spectra: V—substituent interactions at 4-substituted adamantanones and bicyclo[2.2.2]octanones

The ¹³C n.m.r. data of a variety of 4_eq- and 4_ax-substituted adamantanones and bicyclo[2.2.2]octanones are presented. It is shown that for a number of carbons the chemical shifts cannot be predicted by a given additivity rule. The deviations of the observed chemical shifts from the calculated ones are discussed in terms of different interaction mechanisms operating through the σ bond frameworks or through space.     

3(2H)-Furanones from mercuric acetate oxidation of allenic ketones. A synthesis of bullatenone

Treatment of allenic ketones $\underset{?}{1}$ with mercuric acetate yields 3(2H)-furanones $\underset{?}{2}$ (90+%). The oxidation of $\underset{?}{1}\underset{?}{c}$ constitutes a new synthesis of bullatenone $(\underset{?}{2}\underset{?}{c})$.     

Investigation of the interaction of a polyelectrolyte with low molecular weight electrolytes containing nonidentical counterions by differential refractometry

If the counterion of a polyelectrolyte is not identical with any of the ions of a low molecular weight electrolyte added to the solution, the system may be regarded as a four-component system. Relations for the refractive index increments have been derived which allow the determination of the coefficient of selective sorption of the added electrolyte from the refractive index increments of the components independent of the original counterion of the polyelectrolyte. Equilibrium dialysis and differential refractometry were used to study the interaction of KCl, KBr and NaI with poly[-1(2-hydroxyethyl)pyridiniumbenzenesulfonate methacrylate] or with an analogous polymer containing a toluenesulfonate counterion in aqueous solutions. The coefficient of selective sorption increases in the series Cl^? < Br^? < I^? from strongly negative to strongly positive values; the specific interaction of these counterions with the macroion increases in the same order.     

Über das Spektrum von Verbandshomomorphismen in Banach-Verbänden

Ohne Zusammenfassung     

An NMR study of the rates of single-molecule exchange in a cylindrical host capsule

Self-assembled cylindrical capsule 1 is reversibly formed from dimerization of two tetraimide resorcinarenes. Studies of guest exchange involving host capsule 1 reveal a mechanistic continuum for exchange that depends on the structure of the guest. Kinetic and dynamic NMR measurements demonstrate the direct displacement of one guest by another. Surprisingly, in the case of benzene exchange in the pairwise encapsulation of benzene and p-xylene, the incoming benzene occupies the same half of the capsule as the outgoing benzene. As the size of the guests increases, solvent-bridged intermediates determine the rates; empty volumes on the molecular scale need not be invoked.     

Control of chaotic Taylor-Couette flow with time-delayed feedback

We demonstrate that unstable periodic orbits embedded in the experimental chaotic attractor determined by the Taylor-Couette flow can be stabilized with a time-delay autosynchronization algorithm. The optimal parameters of the feedback and their dependence on the control parameter are shown as experimental results.     

Some got away, but others didn't

A history of research projects undertaken in the group-ranging from mechanistic investigations to biomimetic chemistry to molecular devices and synthesis-is presented.