Reactivity of a Cyclopentadienyl Containing Heterobimetallic Alkoxide

The synthesis of the new heteroleptic heterotrimetallic cluster, [(C₅H₅)Sn(μ-OBu^t)₂Ge(OBu^t)Mo(CO)₅] (1) has been achieved by a thermally induced CO substitution of the transition metal derivative, Mo(CO)₆, by the basic germanium atom of the cyclopentadienyl heterobimetallic alkoxide, [(C₅H₅)Sn(μ-OBu^t)₂Ge(OBu^t)]. The microanalysis, molecular weight (monomer in benzene), IR and multinuclear NMR data and X-ray diffraction study is consistent with the formulation of 1. The Sn atom has a trigonal pyramidal coordination environment formed by a aysmmterically π-bonded terminal C₅H₅ ring and two symmetrically bridged tert-butoxy groups. The four-coordinate Ge atom lies at the centre of a distorted tetrahedron and is terminally attached to a tert-butoxy group and a Mo(CO)₅5^? fragment.     

Vertical Electronic Spectra of the Isovalent Molecules H2CNH,H2SiNH,H2CPH and H2SiPH on the Basis of MRD-CI Calculations

Abstract

Large-scale multi-reference single and double-excitation configuration interaction (MRD-CI) calculations are employed for the study of the isovalent compounds H₂CNH, HLSiNH, hLCPH and H₂SiPH in their ground state equilibrium geometry. The dipole moments and charge distributions are given. The vertical excitation energies to the intravalence states ^3,1 (n, π*) and ^3,1(π,π*) and to the first members of the Rydberg series originating from n and - MO's respectively are predicted; the first two ionization potentials and the Rydberg term values are also calculated. In H₂CNH, mixing of Rydberg and valence-shell states with CN stretching is analyzed. The trends in relative stability of electronic and ionized states can be directly related to increased orbital stability of n relative to π as soon as a first-row constituent is replaced by a second-row atom. The calculations explain the diffuse character of the uv spectrum of imines; they treat the molecules H₂SiNH and H₂SiPH for the first time and present a large number of data for all four molecules which can serve as a basis for future experimental investigations on these and related compounds.     

Detection and identification of the designer benzodiazepine flubromazepam and preliminary data on its metabolism and pharmacokinetics

The appearance of pyrazolam in Internet shops selling ‘research chemicals’ in 2012 marked the beginning of designer benzodiazepines being sold as recreational drugs or ‘self medication’. With recent changes in national narcotics laws in many countries, where two uncontrolled benzodiazepines (phenazepam and etizolam), which were marketed by pharmaceutical companies in some countries, were scheduled, clandestine laboratories seem to turn to poorly characterized research drug candidates as legal substitutes. Following the appearance of pyrazolam, it comes with no surprise that recently, flubromazepam (7‐bromo‐5‐(2‐fluorophenyl)‐1,3‐dihydro‐2H‐1,4‐benzodiazepin‐2‐one), a second designer benzodiazepine, was offered on the market. In this article, this new compound was characterized using nuclear magnetic resonance, gas chromatography‐mass spectrometry (GC–MS), liquid chromatography–mass spectrometry (LC–MS/MS) and liquid chromatography quadrupole time‐of‐flight MS (LC–Q–ToF–MS). Additionally, a study was carried out, in which one of the authors consumed 4 mg of flubromazepam to gain preliminary data on the pharmacokinetic properties and the metabolism of this compound. For this purpose, serum as well as urine samples were collected for up to 31 days post‐ingestion and analyzed applying LC–MS/MS and LC–Q‐ToF‐MS techniques. On the basis of this study, flubromazepam appears to have an extremely long elimination half‐life of more than 100 h. One monohydroxylated compound and the debrominated compound could be identified as the predominant metabolites, the first allowing a detection of a consumption for up to 28 days post‐ingestion when analyzing urine samples in our case. Additionally, various immunochemical assays were evaluated, showing that the cross‐reactivity of the used assay seems not to be sufficient for safe detection of the applied dose in urine samples, bearing the risk that it could be misused in drug‐withdrawal settings or in other circumstances requiring regular drug testing. Furthermore, it may be used in drug‐facilitated crimes without being detected. Copyright © 2013 John Wiley & Sons, Ltd.     

Electrical conductivity of poly(vinylidene fluoride)/polyaniline blends under oscillatory and steady shear conditions

Blends of poly(vinylidene fluoride) (PVDF) and polyaniline (PAni) were prepared through melt blending in a batch mixer. The morphology, rheological behavior and electrical conductivity were investigated through transmission electron microscopy (TEM) and combined electro-rheological measurements. Through TEM analysis, it was possible to observe that all blends showed typical phase separation with the presence of conductive polymer aggregates. Deformations imposed during a strain sweep caused, not only disturbance of the linear viscoelastic behavior, but also changes in electrical conductivity. The oscillatory shear altered the morphology, breaking the PAni domains into smaller ones. This effect increases the distance between them and, consequently, resulted in a decrease of the electrical conductivity. The measurements under quiescent conditions and steady shear proved that the disturbance in morphology for PVDF/PAni system is non-recoverable. Through combined electrical and rheological measurements, it was possible to achieve good correlation between the electrical and flow behavior of PVDF/PAni blends.     

Isoporous Block Copolymer Membranes

The developments in membranes based on tailored block copolymers are reported with an emphasis on isoporous membranes. These membranes can be prepared in different geometries, namely flat sheets and hollow fibers. They display narrow pore size distributions due to their formation by self‐assembly. The preparation of these membranes and possibilities to further functionalize such membranes will be discussed. Different ways to control the pore size will be addressed, and the potential of block copolymer blends to fabricate membranes with tailored pore sizes will be shown.

     

Parallel simulation of large scale multibody systems

Virtual prototyping plays an ever increasing role in the engineering disciplines. Nowadays, engineers can rely on powerful tools like object oriented modeling languages, e.g., Modelica. Models written in this language can be simulated by open source software as well as commercial tools. The advantage of this approach is that the engineers can concentrate themselves on modeling, whereas the numerical intricacies of the simulation are handled by the software. On the other hand the simulations are usually slower than implementations which are parallelized and optimized manually. This can lead to computation times which are infeasible in practice, e.g., when a real time simulation is necessary for a hardware-in-the-loop simulation. In this contribution we are concerned with speeding up such automated simulations by parallelization (on desktop hardware as well as HPC systems). We examine the parallelism across the system approaches. Additionally, the influence of the problem formulation on the simulation time is discussed. The implemented methods are demonstrated on engineering examples. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Fixed index gratings in LiNbO(3):Fe upon long-term exposure to an intense laser beam

Permanently fixed noisily recorded refractive index gratings are discovered in single crystals of LiNbO(3):Fe upon long-term exposure to a single laser beam with high intensities of I=100 kW/m(2) and ambient temperature. The fixing process is explained by considering the effect of laser-induced heating of the sample and the well-known simultaneous thermal fixing procedure.