Literatur

Analytical and Bioanalytical Chemistry -     

Synthesis, Characterization, and Reactivity of Dicationic Dihydrogen Complexes of Osmium

The dicationic Os(II) complex [Os(bpy)(PPh(3))(2)(CO)(H(2))](2+) has been prepared as the triflate salt. The presence of a bound dihydrogen ligand is indicated by a short T(1) minimum value consistent with an H-H distance of 1.05 ?. In the partially deuterated derivative J(HD) = 25.5 Hz was observed. By comparison to other structurally characterized complexes, the observed H-D coupling is most consistent with a H-H distance greater than 1 ?, which requires that the bound H(2) ligand be in the slow rotation regime. The dicationic complex is a strong acid, indicating that the bound H(2) is substantially activated toward heterolytic cleavage. The H(2) ligand is tightly bound to the metal center, and does not undergo exchange with D(2) over the course of several weeks at room temperature. A related dicationic Os(II) complex, [Os(bpy)(2)(CO)(H(2))](2+), has also been prepared. A short T(1) minimum value and a J(HD) value of 29.0 Hz in the partially deuterated derivative is most consistent with a H-H distance of 0.99 ?. The bound H(2) ligand of this complex is significantly less activated toward heterolytic cleavage and is stable in solution for less than a day at room temperature.     

Direct discrimination of cell surface glycosylation signatures using a single pH-responsive boronic acid-functionalized polymer

Cell surface glycans serve fundamental roles in many biological processes, including cell–cell interaction, pathogen infection, and cancer metastasis. Cancer cell surface have alternative glycosylation to healthy cells, making these changes useful hallmarks of cancer. However, the diversity of glycan structures makes glycosylation profiling very challenging, with glycan ‘fingerprints’ providing an important tool for assessing cell state. In this work, we utilized the pH-responsive differential binding of boronic acid (BA) moieties with cell surface glycans to generate a high-content six-channel BA-based sensor array that uses a single polymer to distinguish mammalian cell types. This sensing platform provided efficient discrimination of cancer cells and readily discriminated between Chinese hamster ovary (CHO) glycomutants, providing evidence that discrimination is glycan-driven. The BA-functionalized polymer sensor array is readily scalable, providing access to new diagnostic and therapeutic strategies for cell surface glycosylation-associated diseases.

A high-content multichannel sensor array was developed to efficiently discriminate cell states. The binding of boronic acid with glycans is pH-responsive, hence utilizing three pH provides a sensitive multidimensional array from a single polymer.     

Nitrogen‐doped zirconia single crystals

The aim of this work is the preparation of nitrogen‐doped single crystals of cation‐stabilized zirconia. Thin plates of these crystals were nitrided in a graphite heated resistance furnace with nitrogen as reaction gas. Several dwell times and reaction temperatures were tested and their effect on the amount of incorporated nitrogen is investigated. During nitridation at high temperatures a rock salt‐type ‘ZrN’ layer grows on the surface, leading to the destruction of the crystal. In contrast to the fluorite‐type bulk material, which can be described as a fast anion conductor, the surface layer shows electronic conductivity. For possible applications of the bulk material (solid electrolyte) the formation of the surface layer must be avoided. Therefore, the interface between surface epilayer and bulk material was investigated in detail by electron microscopy methods. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Bestimmung des Harnstoffs

Ohne Zusammenfassung     

Electrospray ionization ion mobility spectrometry of carboxylate anions: ion mobilities and a mass-mobility correlation

A number of carboxylate anions spanning a mass range of 87-253 amu (pyruvate, oxalate, malonate, maleate, succinate, malate, tartarate, glutarate, adipate, phthalate, citrate, gluconate, 1,2,4-benzenetricarboxylate, and 1,2,4,5-benzenetetracarboxylate) were investigated using electrospray ionization ion mobility spectrometry. Measured ion mobilities demonstrated a high correlation between mass and mobility in both N2 and CO2 drift gases. Such a strong mass-mobility correlation among structurally dissimilar ions suggests that the carboxylate functional group that these ions have in common is the source of the correlation. Computational analysis was performed to determine the most stable conformation of the studied carboxylate anions in the gas phase under the current experimental conditions. This analysis indicated that the most stable conformations for multicarboxylate anions included intramolecular hydrogen-bonded ring structures formed between the carboxylate group and the neutral carboxyl group. The carboxylate anions that form ring confirmations generally show higher ion mobility values than those that form extended conformations. This is the first observation of intramolecular hydrogen-bonded ring conformation of carboxylate anions in the gas phase at atmospheric pressure.