Recent advances in ultrafast time‐resolved chirality measurements: perspective and outlook

Observing chirality changes as they occur is an important topic of research. It provides information that deepens the understanding of biomolecular configuration and conformation under environmental changes. Also, knowing the specific steps in chiral synthesis would simplify the production of specific chiral enantiomers that have a specific function. To gain better insight to the initial steps of conformational and configurational changes, the time‐resolution of chiral spectroscopy is continually pushed toward a shorter time‐scale. Recent advances have produced measurements of chirality changes with a femtosecond time‐resolution. These measurements are hindered by the inherently weak chirality signal, which can be overshadowed by different optical artefacts. This minireview will look at the so far successful techniques which measure chirality changes with femtosecond time‐resolution and discuss the advantages and disadvantages of these techniques. A short outlook will also look at new techniques that could improve the ability to measure chirality changes on an ultrafast time‐scale.     

A resting state network in the motor control circuit of the basal ganglia

Background  

In the absence of overt stimuli, the brain shows correlated fluctuations in functionally related brain regions. Approximately ten largely independent resting state networks (RSNs) showing this behaviour have been documented to date. Recent studies have reported the existence of an RSN in the basal ganglia - albeit inconsistently and without the means to interpret its function. Using two large study groups with different resting state conditions and MR protocols, the reproducibility of the network across subjects, behavioural conditions and acquisition parameters is assessed. Independent Component Analysis (ICA), combined with novel analyses of temporal features, is applied to establish the basis of signal fluctuations in the network and its relation to other RSNs. Reference to prior probabilistic diffusion tractography work is used to identify the basal ganglia circuit to which these fluctuations correspond.     

Determination of allergy-causing metals from coins

Abstract  The majority of everyday items contain metals and their alloys, although many of them may be harmful to human health. Nickel, originating from different sources such as coins, jewelry, or buttons, represents the most common cause of contact allergy dermatitis. Therefore, the aim of this research work was to estimate the possible risk of allergy resulting from skin exposure to coins. In order to obtain information on the amounts of metals released by their daily use, extraction experiments of coins were performed applying an artificial acidic sweat solution during varying extraction periods. After extraction, the mass of the metals released (copper, iron, nickel, and zinc) were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The mass rate of Ni extracted per area considerably exceeded the permissible values according to the European norm: 50 times for 50-lipa coins, 80 times for 20-lipa coins, and 110 times for 1-kuna coins. This indicates that nickel-containing coins may represent a serious health hazard, especially to sensitive people. Graphical abstract        

A Symmetry Theorem on a Modified Jeu De Taquin

For their bijective proof of the hook-length formula for the number of standard tableaux of a fixed shape Novelli et al. define a modified jeu de taquin which transforms an arbitrary filling of the Ferrers diagram with 1, 2, , n(tabloid) into a standard tableau. Their definition relies on a total order of the cells in the Ferrers diagram induced by a special standard tableau, however, this definition also makes sense for the total order induced by any other standard tableau. Given two standard tableaux P, Q of the same shape we show that the number of tabloids which result in P if we perform the modified jeu de taquin with respect to the total order induced by Q is equal to the number of tabloids which result in Q if we perform the modified jeu de taquin with respect to P. This symmetry theorem extends to skew shapes and shifted skew shapes.     

Mono- and bisadducts from the addition of thianthrene cation radical salts to cycloalkenes and alkenes

Thianthrene cation radical salts, Th(*)(+) X(-)(X(-) = a, ClO(4)(-); b, PF(6)(-); c, SbF(6)(-)), add to cycloalkenes (C(5)-C(8)) in acetonitrile (MeCN) to form 1,2-bis(5-thianthreniumyl)cycloalkane salts and 1,2-(5,10-thianthreniumdiyl)cycloalkane salts, most of which have now been isolated and characterized. These are called bis- (3, 6, 9, 12) and monoadducts (4, 7, 10, 13). The proportional amount of the monoadduct obtained in the initial stage of the reaction varied with the cycloalkene in the order C(6) < C(5) < C(7) < C(8). Thus, the ratio bis:mono for C(5) and C(7) was, respectively, about 80/20 and 50/50. In contrast, only about 5% of the C(6) monoadduct (7a) and none of 7b,c was obtained, while for C(8) none of the bisadducts 12a-c was found. Bisadducts 3 and 9 lost thianthrene (Th) slowly in MeCN solution and changed into monoadducts 4 and 10. A comparable change from 6a into 7a was not observed. The monoadducts, themselves, lost a proton slowly in dry MeCN and opened into 1-(5-thianthreniumyl)cycloalkenes (5, 8, 11, 14). With 3 and 9, particularly, it was possible to follow with NMR spectroscopy the succession of changes, for example, 3 to 4 to 5. The opening of a monoadduct was made faster by adding a small amount of water to the solution. The bisadducts of 4-methylcyclohexene (15a) and 1,5-cyclooctadiene (17a) were isolated and characterized. Although a small amount of monodduct (16a) of 4-methylcyclohexene was found with NMR spectroscopy, it could not be isolated. Bis- and monoadducts were obtained also in additions of Th(*)(+) ClO(4)(-) to acyclic alkenes, in relative amounts that, again, varied with the alkene. From cis-2-butene the dominant product was the bisadduct (18), while the monoaduct (19) was characterized with NMR spectroscopy but could not be isolated. In contrast, trans-3-hexene gave mainly the monoadduct (21), while the bis adduct (20) could not be isolated. With 4-methyl-cis-2-pentene, both bis- (22) and monoadduct (23) were isolated, the former being dominant. The conversion of 18 into 19 was characterized with NMR spectroscopy. In all cycloalkene bisadducts, the configurational relationship of the two thianthrenium groups was trans, while in the monoadducts, the bonds to the single thianthrene dication were (necessarily) cis. In both bis- and monoadducts of acyclic alkenes, the configuration of the alkene was retained. The mechanisms of addition with retention of configuration, of conversion of a bis- into a monoadduct, and of opening of a monoadduct are discussed. Products were identified with a combination of NMR spectroscopy, X-ray crystallography, elemental analysis, and (for cycloalkene adducts) reaction with thiophenoxide ion.     

III. Mitteilung Die Reaktion von Phenol mit 4-Aminoantipyrin

Zusammenfassung Die aus der Literatur in sehr vielen, zum Teil stark unterschiedlichen Verfahren bekannte Reaktion von Phenol mit 4-Aminoantipyrin wurde systematisch untersucht und insbesondere im Hinblick auf ihre Brauchbarkeit für die Biochemie und die physiologische Analyse überprüft. Dabei wurden zum Teil deutliche Abweichungen zu früher publizierten Arbeiten festgestellt. Die Methode ist in ihrer jetzigen Form (als Anwendungsbeispiel wird die Verwendung der Reaktion als Suchreaktion für Phenylester spaltende Fermente des menschlichen Serums nach präparativer elektrophoretischer Auftrennung desselben beschrieben) für alle Belange der physiologischen- und Biochemie brauchbar und zeichnet sich durch besondere Sicherheit und Empfindlichkeit aus. Der Bereich von 0,01–70,0 Mol Phenol kann bei einem mittleren Fehler von ±0,5% (rel.) erfaßt werden. Außerdem können wäßrige Phenollösungen analysiert werden.

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Summary The reaction of phenol with 4-aminoantipyrine (in literature a great deal of partly differing reaction procedures are known) was investigated systematically and checked in particular with a view to its usefulness for biochemistry and physiological analysis. Some distinct deviations from formerly published methods were found. The method in its present form (as an example of application the use of the reaction as a test for phenyl ester-splitting enzymes of human serum after electrophoretic separation into its components is described) is usefull for all tasks of physiological and biochemistry and is characterised in particular by reliability and sensitivity. The range of 0.01 to 70.0 Moles of phenol can be covered with a mean error of ±0.5% (rel.). It is also possible to analyse aqueous phenol solutions.

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II. Mitteilung: Pilz, W., u. I. Johann: diese Z. 210, 358 (1965).     

Polyethylene with Reverse Co‐monomer Incorporation: From an Industrial Serendipitous Discovery to Fundamental Understanding

A triethylaluminium(TEAl)‐modified Phillips ethylene polymerisation Cr/Ti/SiO₂ catalyst has been developed with two distinct active regions positioned respectively in the inner core and outer shell of the catalyst particle. DRIFTS, EPR, UV‐Vis‐NIR DRS, STXM, SEM‐EDX and GPC‐IR studies revealed that the catalyst produces simultaneously two different polymers, i.e., low molecular weight linear‐chain polyethylene in the Ti‐abundant catalyst particle shell and high molecular weight short‐chain branched polyethylene in the Ti‐scarce catalyst particle core. Co‐monomers for the short‐chain branched polymer were generated in situ within the TEAl‐impregnated confined space of the Ti‐scarce catalyst particle core in close proximity to the active sites that produced the high molecular weight polymer. These results demonstrate that the catalyst particle architecture directly affects polymer composition, offering the perspective of making high‐performance polyethylene from a single reactor system using this modified Phillips catalyst.     

Trace elemental characterization of edible oils by ICP-AES and GFAAS

A method for the determination of the inorganic profile in edible oils is proposed. The quantification of selected metals in various oils (olive, pumpkin seed, sunflower, sesame seed, hazelnut, grape, soya, rice oil) was carried out using microwave assisted digestion followed by ICP-AES and GFAAS. The detection power of the ICP-AES technique was sufficient for the determination of Ca, Fe, Mg, Na, and Zn. Since the samples contained very low amounts of Al, Cu, Co, Cr, K, Ni, Mn, and Pb, these elements were measured by GFAAS. Differences of metal concentrations for edible oils obtained in this preliminary study represent a starting basis for the development of an additional analytical procedure applicable for oil characterization.     

A simple synthesis of symmetric phthalocyanines and their respective perfluoro and transition‐metal complexes

We report a simple synthesis protocol for making phthalocyanines (Pcs) starting from phthalonitriles. This method is general and requires no specialised equipment. The complexes are isolated and characterised using X‐ray diffraction, NMR, FTIR and Raman spectroscopy and high‐resolution mass spectrometry. First, we study and present a one‐step synthesis route to a metal‐free Pc (H₂PcH₁₆), as well as to the corresponding MPcH₁₆ complexes of Mn, Fe, Co, Ni, Cu and Zn. Then, we show that this route can also be used to make the fluorinated Pc analogues (MPcF₁₆). Finally, we present a new and useful procedure for inserting a metal ion into a metal‐free H₂PcH₁₆ ring, by direct metalation, yielding the corresponding MPcH₁₆ complex. This last method is especially useful if you want to make different MPcH₁₆ complexes.