Analytische Anwendung von Polymethylenammoniumsalzen

Zusammenfassung Unter den Hexamethonium [HM]-Übergangsmetall-Halogeniden, bzw. Halogenoiden, von welchen eine Reihe der komplexen Rhodanide beschrieben werden, sind die Verbindungen [HM][PtCl₆], [HM][PdCl₄] und [HM][IrCl₆] zum Nachweis der betreffenden Platinmetalle mit Empfindlichkeiten zwischen 0,2 und 3g Metall geeignet. Das Hexamethonium-Ion kann als [HM][Cr(NCS)₄(NH₃)₂]₂ in Mengen ab 1,5 mg gravimetrisch bestimmt werden.

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Summary The hexamethonium [HM] compounds of transition metal halogenides and halogenoides have been examined and some complex rhodanides have been described. The compounds [HM][PtCl₆], [HM][PdCl₄], and [HM][IrCl₆] have proved to be suitable for the detection of the metals concerned with sensitivities between 0,2 and 3g of the metal. The gravimetric determination of the hexamethonium ion in quantities above 1.5mg has been achieved by help of the compound [HM][Cr(NCS)₄(NH₃)₂]₂.

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II. Teil:Ziegler, M., u. G.Pape ¹.

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HerrWolfgang Renner hat in dankenswerter Weise Darstellung und Analysen der Rhodanokomplexe ausgeführt.     

The chemistry of coordinate polymerization of dienes

Conclusions This review has brought together the diverse ionic initiators for dienes into a consistent series of four polymerization mechanisms. The ionic freedom characteristic of the electrophilic and free anionic initiators catalyze the rapid formation of 1–4 trans structures. Coordinate initiation produces 1–4 cis structures via a cyclic transition state while anionic initiation produces 1–2 (3–4) structures.The catalytic activity in the coordinate and anionic catalysts depends largely on complex formation. The equilibrium characteristics of complex formation produces the different rate, structure and molecular weight effects observed in coordinate initiation studies.I wish to thank Drs. P. H.Moyer and M. R.Frederick for many helpful discussions of the mechanisms of coordinate polymerizations.     

Untersuchungen über Phenthiazinderivate, 19. Mitt. Neue piperazinsubstituierte Phenthiazine

Zusammenfassung Es wird über die Einführung weiterer Substituenten, z. B. Cyanäthyl und Aminopropyl, in Piperazinylalkylphenthiazine und -Piperazinyl-4,10-trimethylenphenthiazin berichtet.18. Mitt. dieser Reihe:O. Hromatka, M. Knollmüller undF. Sauter, Mh. Chem.93, 723 (1962).     

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Isomer Information from Ion Mobility Separation of High-Mannose Glycan Fragments

Extracted arrival time distributions of negative ion CID-derived fragments produced prior to traveling-wave ion mobility separation were evaluated for their ability to provide structural information on N-linked glycans. Fragmentation of high-mannose glycans released from several glycoproteins, including those from viral sources, provided over 50 fragments, many of which gave unique collisional cross-sections and provided additional information used to assign structural isomers. For example, cross-ring fragments arising from cleavage of the reducing terminal GlcNAc residue on Man₈GlcNAc₂ isomers have unique collision cross-sections enabling isomers to be differentiated in mixtures. Specific fragment collision cross-sections enabled identification of glycans, the antennae of which terminated in the antigenic α-galactose residue, and ions defining the composition of the 6-antenna of several of the glycans were also found to have different cross-sections from isomeric ions produced in the same spectra. Potential mechanisms for the formation of the various ions are discussed and the estimated collisional cross-sections are tabulated.

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Ultraparamagnetic Cells Formed through Intracellular Oxidation and Chelation of Paramagnetic Iron

Making cells magnetic is a long‐standing goal of chemical biology, aiming to enable the separation of cells from complex biological samples and their visualization in vivo using magnetic resonance imaging (MRI). Previous efforts towards this goal, focused on engineering cells to biomineralize superparamagnetic or ferromagnetic iron oxides, have been largely unsuccessful due to the stringent required chemical conditions. Here, we introduce an alternative approach to making cells magnetic, focused on biochemically maximizing cellular paramagnetism. We show that a novel genetic construct combining the functions of ferroxidation and iron chelation enables engineered bacterial cells to accumulate iron in “ultraparamagnetic” macromolecular complexes, allowing these cells to be trapped with magnetic fields and imaged with MRI in vitro and in vivo. We characterize the properties of these cells and complexes using magnetometry, nuclear magnetic resonance, biochemical assays, and computational modeling to elucidate the unique mechanisms and capabilities of this paramagnetic concept.     

Mimicking Class I b Mn2‐Ribonucleotide Reductase: A MnII2 Complex and Its Reaction with Superoxide

A fascinating discovery in the chemistry of ribonucleotide reductases (RNRs) has been the identification of a dimanganese (Mn₂) active site in class I b RNRs that requires superoxide anion (O₂^.?), rather than dioxygen (O₂), to access a high‐valent Mn₂ oxidant. Complex 1 ([Mn₂(O₂CCH₃)(N‐Et‐HPTB)](ClO₄)₂, N‐Et‐HPTB=N,N,N′,N′‐tetrakis(2‐(1‐ethylbenzimidazolyl))‐2‐hydroxy‐1,3‐diaminopropane) was synthesised in high yield (90 %). 1 was reacted with O₂^.? at ?40 °C resulting in the formation of a metastable species ( 2 ). 2 displayed electronic absorption features (λ_max=460, 610 nm) typical of a Mn‐peroxide species and a 29‐line EPR signal typical of a Mn^IIMn^III entity. Mn K‐edge X‐ray absorption near‐edge spectroscopy (XANES) suggested a formal oxidation state change of Mn^II₂ in 1 to Mn^IIMn^III for 2 . Electrospray ionisation mass spectrometry (ESI‐MS) suggested 2 to be a Mn^IIMn^III‐peroxide complex. 2 was capable of oxidizing ferrocene and weak O?H bonds upon activation with proton donors. Our findings provide support for the postulated mechanism of O₂^.? activation at class I b Mn₂ RNRs.