Directed graphs of inner translations of semigroups

A mapping \(\alpha :S\rightarrow S\) is called a Cayley function if there exist an associative operation \(\mu :S\times S\rightarrow S\) and an element \(a\in S\) such that \(\alpha (x)=\mu (a,x)\) for every \(x\in S\). The aim of the paper is to give a characterization of Cayley functions in terms of their directed graphs. This characterization is used to determine which elements of the centralizer of a permutation on a finite set are Cayley functions. The paper ends with a number of problems.     

Thermodynamics of Self-Assembly of Dicarboxylate Ions with Binuclear Lanthanide Complexes

Self-assembly of a range of carboxylic acids (benzoic acid, dinicotinic acid, nicotinic acid, and isophthalic acid) with the europium complex of 5-nitro-α,α′-bis(DO3Ayl)-m-xylene (where DO3A is 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid) has been explored to establish the thermodynamics of binding in a range of solvent systems and in a range of aqueous buffer solutions. In this system, profound effects are observed as a consequence of competition by the hydroxide ion, which outcompetes even dinicotinate at high pH. In the case of isophthalate, which binds most strongly, and dinicotinate, both enthalpic and entropic contributions to binding have been identified. The europium complex with 5-nitro-α,α′-bis(DO3Ayl)-m-xylene is found to have a solution structure significantly different from the related europium complex of 5-amino-α,α′-bis(DO3Ayl)-m-xylene. It is found that phosphate binds strongly to the europium complex of the nitro derivate but not to the europium complex of amino derivative. Lactate, citrate, and pyruvate also bind strongly to 5-nitro-α,α′-bis(Eu⋅DO3Ayl)-m-xylene, and it is concluded that the solution structure of this binuclear lanthanide complex is significantly different from that of the amino-substituted complex.     

The Corrole Radical

The reaction of 5,10,15‐trimesitylcorrole (H₃cor) with tungsten hexachloride and tungsten hexacarbonyl resulted in the unexpected formation of the 3,17‐dichloro‐5,10,15‐trimesitylcorrole radical (H₂cor*) as an air‐stable product. X‐ray crystallography proved the planarization of the corrole radical structure, which was rationalized by the reduced steric hindrance of two versus three hydrogen atoms inside the N₄ cavity. Although the aromaticity was lost, no specific changes in C? C or C? N bond distances could be observed. The regioselectivity of the two‐fold chlorination is the result of the nucleophilic attack of chloride ions to an oxidized corrole macrocycle, and is supported by DFT results. The corrole radical acts as a dianionic ligand and allows the insertion of the divalent zinc(II) cation, which usually does not form neutral corrole complexes.     

Properties of Ca-containing LiCoPO<Subscript>4</Subscript>-graphitic carbon foam composites

LiCo_1???x Ca _x PO₄–graphitic carbon foam composites are prepared using a sol–gel method. The structural analysis reveals LiCoPO₄ as major crystalline phase and Co₂P₂O₇ (for x?=?0.0) and Co₂P, Li₃PO₄, and (Ca,Co)₃(PO₄)₂ (for x?≥?0.05) as secondary phases. The morphology consists of microcrystalline “islands” with acicular crystallites (5–50 μm size). Transmission electron microscopy (TEM) of the powders showed that the Ca is incorporated into the crystal structure evoking exaggerated grain growth. The voltammetric profiles show a decrease of the voltammetric surface between anodic and cathodic sweeps and a shift of the reduction potentials toward higher values (～4.6 V, x?=?0.1). The electrochemical measurements, at a discharge rate of C/10 (room temperature), show an increase of the discharge-specific capacity from 100 mAhg^?1 for x?=?0.0 to 104 mAhg^?1 for x?=?0.1. The ac impedance spectroscopy data revealed an improvement of the Li-ion conductivity at high content of Ca ions (x?=?0.1).     

A GENERAL ROUTE TO TIN-NITROGEN HETEROCUBANES

The reaction of the lithiated bis-stannylamine, ((CH₃)₃)Sn₂NLi·THF (1), with (C₅H₅)₂ZrCl₂ yields the imido-bridged zirconium dimer, [(C₅H₅)₂ZrN(Sn(CH₃)₃)]₂ (3), which was characterized by single crystal x-ray diffractometry. The heteroleptic stannylamine, [{(CH₃)₃Sn}{(CH₃)₃Si}]NLi·Et₂O(2), prepared using(1)as a synthetic precursor, reacts with SnCl₂ to yield the tin-nitrogen heterocubane, [Sn(μ₃-NSi(CH₃)₃)]₄ (4), which is fully characterized by single crystal x-ray diffractometry and standard spectroscopic techniques. The use of this class of stannylamine ligands allows access to heterometallic amido complexes and provides a general route to obtaining tin-nitrogen heterocubanes.     

Einen Apparat zum Filtrieren in feuchtigkeitsfreien oder indifferenten Gasen

Ohne Zusammenfassung     

Combination of different liquid chromatography/mass spectrometry technologies for the identification of transformation products of rhodamine B in groundwater

Rhodamine B and its five de‐ethylated transformation products could be identified in a groundwater sample. Using high‐performance thin‐layer chromatography (HPTLC) six fluorescent zones were detected in the sample. In order to identify the compounds in the zones by exact mass mass spectrometry (MS) measurements and tandem mass spectrometry (MS/MS), they were extracted from the HPTLC plate for subsequent analysis by nano‐chip high‐performance liquid chromatography quadrupole‐time‐of‐flight mass spectrometry (nano‐chip HPLC/QTOFMS). In addition, chemical derivatisation experiments on HPTLC plates were applied to detect the presence of a primary amino group in the transformation products. From the combined analytical results it was possible to allocate rhodamine B and its five de‐ethylated transformation products to the six different HPTLC zones. The quantification of rhodamine B in different groundwater samples was carried out by a high‐performance liquid chromatography/triple quadrupole mass spectrometry (HPLC/MS/MS). The maximum detected concentration of rhodamine B was 83 µg L^?1. Copyright © 2010 John Wiley & Sons, Ltd.