Ab initio calculation of magnetic properties by the “direct” IGLO method

A direct method for the ab initio calculation of the magnetic susceptibility and chemical shielding tensors based on the individual gauge for localized molecular orbitals (IGLO) formalism is introduced. “Direct” in this context means we avoid storing the two-electron repulsion integrals in favor of recalculating them whenever necessary. In conjunction with the Direct-SCF package TURBOMOLE Direct IGLO (DIGLO) permits calculation of magnetic second-order properties for large molecules by minimizing peripheral disc storage requirements. The size of the molecules to be treated is limited only by the amount of CPU time available. The performance of DIGLO is demonstrated for some selected examples.     

An Allosteric Receptor by Simultaneous “Casting” and “Molding” in a Dynamic Combinatorial Library

Allosteric synthetic receptors are difficult to access by design. Herein we report a dynamic combinatorial strategy towards such systems based on the simultaneous use of two different templates. Through a process of simultaneous casting (the assembly of a library member around a template) and molding (the assembly of a library member inside the binding pocket of a template), a Russian‐doll‐like termolecular complex was obtained with remarkable selectivity. Analysis of the stepwise formation of the complex indicates that binding of the two partners by the central macrocycle exhibits significant positive cooperativity. Such allosteric systems represent hubs that may have considerable potential in systems chemistry.     

“Superpermeability” and “pumping” of atomic hydrogen through palladium membranes

Permeation of atomic as well as molecular hydrogen through palladium membranes has been investigated experimentally in the temperature range from room temperature to 200 °C and at a higher incident flux of hydrogen atoms on palladium surface than in previous studies. The results demonstrate that phenomena of ‘superpermeability’ and ‘pumping’ of atomic gases through metal membranes are of a common nature. A theoretical model based on chemical thermodynamics and diffusion theory adequately describes the quantitative relationships observed in experiments. It was found that permeability of atomic hydrogen depends strongly on the magnitude of surface incident flux and membrane temperature.     

Examples of “intrinsically” and “extrinsically” determined phase morphologies in polymer alloys

The properties of polymer alloys are strongly dependent on their phase morphologies. Usually, the phase dispersion and domain sizes are affected by the process and can be influenced and stabilized only “extrinsically” by dispersants and emulsifiers. But, there are some examples of alloys with phase morphologies which are “intrinsically” determined and thus independently of the processing conditions. This aspect of phase determining factors is discussed using four principally different examples of polymer alloys.