Ruthenium complexes containing group 5b donor ligands : Part VII. Rearrangement reactions of some ruthenium (II) complexes containing triphenylphosphine,tri-p-tolylphosphine or ethyldiphenylphosphine ligands.

As for [RuCl₂(PPh₃₃], carbonylation of [RuCl₂(PR₃)₃] [PR₃ = P(p-tolyl)₃, PEtPh₂) in N,N ¹-dimethylformamide (dmf) gives [Ru(CO)Cl₂ (dmf) (PR₃)₂] (II). For PR₃ = PEtPh₂, rearrangement of (II) in various solvents gives inseparable mixtures (³¹P evidence) but for PR₃ = P(p-tolyl)₃ [Ru₂(CO)₂Cl₄-{P(p-tolyl)₃}₃]is obtained. Reaction of [Ru(CO)Cl₂ (dmf) - {P(p-tolyl)₃}₂] with [RuCI₂{(P(p-tolyl)₃}₃] (1:1 mol ratio) gives [Ru₂ (CO) Cl₄ {P (p-tolyl)₃}₄] whereas reaction of [Ru (CO) Cl₂ (dmf) - (PPh₃₂] with (Rul₂ {P (p-tolyl)₃}₃] gives [Ru₂(CO)Cl₄ (PPh₃)₂] - {P(p-tolyl)₃}₂] - Reaction of [RuCl₂ {P(p-tolyl)₃}₃] with CS₂ gives the related [Ru₂Cl₄(CS) {P(p-tolyl)₃}₄] and [{RuCl₂(CS)}P(p-tolyl)₃{₂}₂] whereas [RuCl₂(PEtPh₂)₃] and CS₂ produce [RuCl₂(S₂CPEtPh₂) (PEtPh₂)₂]CS₂ and [Ru₂Cl₄(CS)₂(PEtph₂)₃].     

A validated LC-MSMS method for the simultaneous quantification of meropenem and vaborbactam in human plasma and renal replacement therapy effluent and its application to a pharmacokinetic study

A simple method for the simultaneous quantification of meropenem and the recently approved β-lactamase inhibitor, vaborbactam, in human plasma and renal replacement therapy effluent (RRTE) was developed and validated. This antibiotic combination protects a primary β-lactam, meropenem, with a new β-lactamase inhibitor, and expands the limited options for treatment of multidrug-resistant Gram-negative infections. Meropenem, vaborbactam, and the internal standards [²H₆]-meropenem and sulbactam in plasma and RRTE were processed using acetonitrile followed by a chromatographic separation on a Poroshell HPH-C18 column with a gradient elution of the mobile phases and monitored using mass spectrometry detection. The calibration range was 0.05 to 100 μg mL⁻¹ for both meropenem and vaborbactam. The intra-day and inter-day precision and accuracy were less than 15% for both meropenem and vaborbactam and the recovery from plasma was 96% for both meropenem and vaborbactam and the recovery from RRTE was 93% and 103% for meropenem and vaborbactam, respectively. This methodology was successfully applied to an ex vivo characterisation study of the effects of renal replacement therapy modalities on the pharmacokinetics of meropenem and vaborbactam (Antimicrob Agents Chemother 62(10), 2018).

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Evaluation of separation in gradient elution ion chromatography by combining several retention models and objective functions

In this work, three different methods for modeling of gradient retention were combined with several optimization objective functions in order to find the most appropriate combination to be applied in ion chromatography method development. The system studied was a set of seven inorganic anions (fluoride, chloride, nitrite, sulfate, bromide, nitrate, and phosphate) with a KOH eluent. The retention modeling methods tested were multilayer perceptron artificial neural network (MLP-ANN), radial-basis function artificial neural network (RBF-ANN), and retention model based on transfer of data from isocratic to gradient elution mode. It was shown that MLP retention model in combination with the objective function based on normalized retention difference product was the most adequate tool for optimization purposes.     

An Inconvenient History: the Nuclear-Fission Display in the Deutsches Museum

One of the longstanding attractions of the Deutsches Museum in Munich, Germany, has been its display of the apparatus associated with the discovery of nuclear fission. Although the discovery involved three scientists, Otto Hahn, Lise Meitner, and Fritz Strassmann, the fission display was designated for over 30 years as the Arbeitstisch von Otto Hahn (Otto Hahn’s Worktable), with Strassmann mentioned peripherally and Meitner not at all, and it was not until the early 1990s that the display was revised to include all three codiscoverers more equitably. I examine the creation of the fission display in the context of the postwar German culture of silencing the National Socialist past, and trace the eventual transformation of the display into a contemporary exhibit that more accurately represents the scientific history of the fission discovery.     

The Politics of Forgetting: Otto Hahn and the German Nuclear-Fission Project in World War II

As the co-discoverer of nuclear fission and director of the Kaiser Wilhelm Institute for Chemistry, Otto Hahn (1879–1968) took part in Germany‘s nuclear-fission project throughout the Second World War. I outline Hahn’s efforts to mobilize his institute for military-related research; his inclusion in high-level scientific structures of the military and the state; and his institute’s research programs in neutron physics, isotope separation, transuranium elements, and fission products, all of potential military importance for a bomb or a reactor and almost all of it secret. These activities are contrasted with Hahn’s deliberate misrepresentations after the war, when he claimed that his wartime work had been nothing but “purely scientific” fundamental research that was openly published and of no military relevance.     

Crystal and molecular structure of 4,4′-dichlorodiphenyl sulphone, 4,4′-dibromodiphenyl sulphone and 4,4′-diiododiphenyl sulphone

The crystal and molecular structure of 4,4-dichloro-diphenyl sulphone (A), 4,4-dibromodiphenyl sulphone (B) and 4,4-diiododiphenyl sulphone (C) have been determined from three-dimensional MoK. diffractometer data. These structures are isomorphous in the monoclinic space groupI2/a, with four molecules per unit-cell. The cell dimensions ofA,B andC area = 20.216 (4),b = 5.004(1),c = 12.248(2) Å, = 90 °34(1);a = 20.813(10),b = 5.055(3),c = 12.421(9) Å, = 92 °46(2) anda = 19.762(8),b = 4.947(2),c = 14.480(5) Å, =103 ° 18(1), respectively. Least-squares refinements converged toR-factors of 6.0% over 925 reflections, 6.8% over 1273 reflections and 3.8% over 995 reflections forA,B andC, respectively.The S—O bond lengths are 1.432(3), 1.453(5) and 1.445(7) Å and the S—C bond lengths 1.766(4), 1.764(6) and 1.756(7) Å inA,B andC, respectively. The C—Cl, C—Br and H—-I bond lengths are 1.748(5), 1.905(6) and 2.103(7) Å, respectively. The dihedral angle between the plane of each aromatic ring and the C—S—C plane is 84.6 ° inA, 83.8 ° inB and 86.9 ° inC. Intermolecular BrBr and II contacts of 3.65 and 3.90 Å are considerably shorter than the van der Waals contacts given by Pauling.     

Corresponding states of nematic birefringence: an order parameter universality

In this work, experimental birefringence data of several nematic liquid crystals, which share the presence of a nematic–isotropic and a nematic–crystalline phase transition, are used to show that the birefringence presents a universal behaviour which encompasses the entire range of the nematic phase. The meaning and consequences of such behaviour are discussed; as the order parameter is proportional to the birefringence, this result implies that the order parameter has an extended universal profile, similar to a corresponding state law, which is independent of the liquid crystal compound and becomes determined once the temperature interval of the existence of the nematic compounds is obtained.     

Corresponding states in the smectic-A phase

In the last few years, experimental data of many different sources has been gathered to show that order parameter curves of essentially all nematic liquid crystals (NLCs) compounds can be reduced to a single and universal curve of the corresponding states; experimental data of an impressive number of different nematic compounds has been linearly rescaled in such a way that all them coalesced in a single curve. The surprising novelty observed on NLCs is that this universal behaviour is not restricted to the neighbourhoods of a critical region, as is usually expected from critical phenomena, but it covers the entire domain of the nematic phase, from the nematic isotropic temperature to the nematic crystalline temperature. The aim of this paper is to study the statistical mechanics fundamentals of this behaviour and show that it is a consequence of the universality of the angular part of the potential of the interaction between the particles composing the liquid crystal (LC). We will illustrate this behaviour presenting evidences that it can be found on the smectic-A phase.     

A dielectric study of three chiral liquid crystals presenting SmC*FI phases

We have performed a detailed dielectric study of three compounds presenting ferrielectric phases over large temperature intervals. The relaxation processes detected in the SmC*_FI phases are highly polidispersive. We have repeatedly observed the surface layer mode described by Bourny et al. [1] and a weak ferrielectric mode, whose relaxation frequency is always higher on heating than on cooling runs. The temperature interval where SmC*_FI phases occur is apparently independent of cooling/heating rates and of the history of the sample.