The Trifluoromethyl Anion

First evidence for the existence of free trifluoromethyl anion CF₃^? has been obtained. The 3D‐caged potassium cation in [K(crypt‐222)]⁺ is inaccessible to CF₃^?, thus rendering it uncoordinated (“naked”). Ionic [K(crypt‐222)]⁺ CF₃^? has been characterized by single‐crystal X‐ray diffraction, solution NMR spectroscopy, DFT calculations, and reactivity toward electrophiles.     

Shape-persistent linear, kinked, and cyclic oligo(phenylene-ethynylene-butadiynylene)s: self-assembled monolayers

Shape-persistent rigid phenylene-ethynylene-butadiynylenes form lamellar self-assembled monolayers (SAMs) at the HOPG/TCB interface, which were studied by scanning tunneling microscopy (STM) with submolecular resolution. Substitution of the terminating acetylene functions with polar cyanopropyldimethylsilyl groups leads to 2D phase separation and defined rod-rod interactions, which determine the packing distances between the rigid rods. The results stimulated the connection of rigid rods via septiarylene clamp units. They covalently link two rigid rod units and define the intramolecular rod-rod distance that matches the alkoxy substituent chain lengths. The systems can be described as half-ring structures of two rigid rods connected via a rotatable joint unit. These acetylene-terminated half-ring structures were also oligomerized under Cu and Pd catalysis to yield defined acyclic and cyclic oligomers. Detailed STM studies decoded the molecular origin of the surface patterning of such systems. The dodecyloxy side chains are adsorbed along the HOPG main axes and, together with the alkoxy backbone angle, determine the adsorption direction of the adlayers.     

Nanocelluloses: a new family of nature-based materials

Cellulose fibrils with widths in the nanometer range are nature-based materials with unique and potentially useful features. Most importantly, these novel nanocelluloses open up the strongly expanding fields of sustainable materials and nanocomposites, as well as medical and life-science devices, to the natural polymer cellulose. The nanodimensions of the structural elements result in a high surface area and hence the powerful interaction of these celluloses with surrounding species, such as water, organic and polymeric compounds, nanoparticles, and living cells. This Review assembles the current knowledge on the isolation of microfibrillated cellulose from wood and its application in nanocomposites; the preparation of nanocrystalline cellulose and its use as a reinforcing agent; and the biofabrication of bacterial nanocellulose, as well as its evaluation as a biomaterial for medical implants.     

A Self‐Improved Water‐Oxidation Catalyst: Is One Site Really Enough?

The homogeneous catalysis of water oxidation by transition‐metal complexes has experienced spectacular development over the last five years. Practical energy‐conversion schemes, however, require robust catalysts with large turnover frequencies. Herein we introduce a new oxidatively rugged and powerful dinuclear water‐oxidation catalyst that is generated by self‐assembly from a mononuclear catalyst during the catalytic process. Our kinetic and DFT computational analysis shows that two interconnected catalytic cycles coexist while the mononuclear system is slowly and irreversibly converted into the more stable dinuclear system: an extremely robust water‐oxidation catalyst that does not decompose over extended periods of time.     

Generalized nuclearity conditions and the split property in quantum field theory

Generalized nuclearity conditions that are applicable in arbitrary superselection sectors of a quantum field theory and to theories with a maximal temperature are discussed. They are shown to imply the (distal) split property and to impose specific restrictions on the spectral properties of modular operators associated with local algebras and vectors of compact energy support.     

Matrixunabh?ngige kontinuierliche Dampfraum-Gas-Chromatographie

Zusammenfassung Ausgehend von systematischen Untersuchungen des Matrixeinflusses bei der gas-chromatischen Dampfraum-Analyse und aufgrund prinzipieller Überlegungen wird ein neues Arbeitsverfahren vorgestellt, das es erlaubt, sehr viele Stoffe matrixunabhängig zu bestimmen. Dieses wird durch eine fast quantitative Überführung der flüchtigen Komponenten in das Strip-Gas durch Zusatz von Salzlösungen und durch eine kontinuierliche multiple Gegenstromextraktion über einem strömenden Flüssigkeitsfilm erreicht. Die daraus erwachsenden Vorteile dieses Verfahrens gegenüber der herkömmlichen Technik werden anhand von Beispielen erläutert und aufgezeigt.

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Matrix-independent continuous Head-Space gas-chromatography

Summary A new Head-Space gas-chromatography is presented by means of which it is possible to perform a continuous and selective measurement of numerous organic components dissolved in water. By addition of salt solutions to the sample and a continuous multiple distribution between a thin film of the fluid sample and an inert strip-gas, organic components are nearly quantitatively transferred from the water sample to the strip-gas. The transfer is widely unaffected by the matrix components. The strip-gas, containing more then 95% of the organic components, is analyzed by gas-chromatography. The advantages of the new method as against the hitherto used techniques are demonstrated by means of several examples.

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Die vorliegende Arbeit wurde mit Mitteln des Ministers für Wissenschaft und Forschung des Landes Nordrhein-Westfalen gefördert. Dafür sei an dieser Stelle herzlich gedankt.