Cover Picture: On the Function and Structure of Synthetically Modified Porins (Angew. Chem. Int. Ed. 26/2009)

Synthetic Modulators are introduced into the trimeric porin OmpF by protein semisynthesis/click chemistry or by S‐alkylation, as U. Koert, L.‐O. Essen et al. report in their Communication on page 4853 ff. The choice of synthetic modulator and the type of covalent attachment significantly affect the blockage efficiency. A model for the functional properties is postulated on the basis of an X‐ray structure analysis of a crown ether/OmpF hybrid.

     

Cover Picture: Angew. Chem. Int. Ed. 13/2002

The cover picture shows benzoborirene, the product of the crossed‐molecular‐beam reaction between benzene molecules and boron atoms, displayed above the three‐dimensional plot of the angular‐ and translational‐energy‐dependent flux of the benzoborirene molecules in the center‐of‐mass system. As the reaction conditions preclude secondary collisions, the intermediate initially formed from the reactive collision decays by ejection of a hydrogen atom. The structure of the benzoborirene depicted is based on a DFT computation, which, combined with results of highly accurate coupled‐cluster calculations has been used to assign the reaction product by comparing experimental and theoretical reaction energies. Details are described by R. I. Kaiser and H. F. Bettinger on p. 2350 ff.     

Selective Ion Exchange in Supramolecular Channels in the Crystalline State

Artificial ion channels are of increasing interest because of potential applications in biomimetics, for example, for realizing selective ion permeability through the transport and/or exchange of selected ions. However, selective ion transport and/or exchange in the crystalline state is rare, and to the best of our knowledge, such a process has not been successfully combined with changes in the physical properties of a material. Herein, by soaking single crystals of Li₂([18]crown‐6)₃[Ni(dmit)₂]₂(H₂O)₄ ( 1 ) in an aqueous solution containing K⁺, we succeeded in complete ion exchange of the Li⁺ ions in 1 with K⁺ ions in the solution, while maintaining the crystalline state of the material. This ion exchange with K⁺ was selectively conducted even in mixed solutions containing K⁺ as well as Na⁺/Li⁺. Furthermore, remarkable changes in the physical properties of 1 resulted from the ion exchange. Our finding enables not only the realization of selective ion permeability but also the development of highly sensitive biosensors and futuristic ion exchange agents, for example.     

Cover Picture: Metal–Organic Spheres as Functional Systems for Guest Encapsulation (Angew. Chem. Int. Ed. 13/2009)

The infinite coordination polymerization…? of metal ions and multitopic organic ligands is explored to fabricate metal–organic micro‐ and nanospheres that can be used as functional matrices. In their Communication on page 2325 ff., D. Maspoch and co‐workers show how this simple process affords spheres that encapsulate active substances, such as magnetic nanoparticles, organic dyes, and quantum dots, to result in multifunctional spheres. Marianne Verdoux is thanked for the cover graphic design.