Transparent conducting Sn:ZnO films deposited from nanoparticles

Homogeneous transparent conducting Sn:ZnO films on fused silica substrates were prepared by dip-coating from nanoparticle dispersions, while the nanocrystalline Sn:ZnO particles with different dopant concentrations were synthesized by microwave-assisted non-aqueous sol–gel process using Sn(IV) tert-butoxide and Zn(II) acetate as precursors and benzyl alcohol as solvent. The dopant concentration had a great impact on the electrical properties of the films. A minimum resistivity of 20.3 Ω cm was obtained for a porous Sn:ZnO film with initial Sn concentration of 7.5 mol% after annealing in air and post-annealing in N₂ at 600 °C. The resistivity of this porous film could further be reduced to 2.6 and 0.6 Ω cm after densified in Sn:ZnO and Al:ZnO reaction solution, respectively. The average optical transmittance of a 400-nm-thick Sn:ZnO film densified with Sn:ZnO after the two annealing steps was 91%.     

Heterobimetallic Cuprates Consisting of a Redox‐Switchable,Silicon‐Based Metalloligand: Synthesis,Structures, and Electronic Properties

A series of bimetallic silyl halido cuprates consisting of the new tripodal silicon‐based metalloligand [κ³N‐Si(3,5‐Me₂pz)₃Mo(CO)₃]^? is presented (pz=pyrazolyl). This metalloligand is straightforwardly accessible by reacting the ambidentate ligand tris(3,5‐dimethylpyrazolyl)silanide ({Si(3,5‐Me₂pz)₃}^?) with [Mo(CO)₃(η⁶‐toluene)]. The compound features a fac‐coordinated tripodal chelating ligand and an outward pointing, “free” pyramidal silyl donor, which is easily accessible for a secondary coordination to other metal centers. Several bimetallic silyl halido cuprates of the general formula [CuX{μ‐κ¹Si:κ³N‐Si(3,5‐Me₂pz)₃Mo(CO)₃}]^? (X=Cl, Br, I) have been synthesized. The electronic and structural properties of these complexes were probed in detail by X‐ray diffraction analysis, electrospray mass spectrometry, infrared‐induced multiphoton dissociation studies, cyclic voltammetry, spectroelectrochemistry, gas‐phase photoelectron spectroscopy, as well as UV/Vis and fluorescence spectroscopy. The heterobimetallic complexes contain linear two‐coordinate copper(I) entities with the shortest silicon–copper distances reported so far. Oxidation of the anionic complexes in methylene chloride and acetonitrile solutions at ${E{{0\hfill \atop 1/2\hfill}}}$ =?0.60 and ?0.44 V (vs. ferrocene/ferrocenium (Fc/Fc⁺)), respectively, shows substantial reversibility. Based on various results obtained from different characterization methods, as well as density functional theory calculations, these oxidation events were attributed to the Mo⁰/Mo^I redox couple.     

First total synthesis of the marine steroid alkaloid plakinamine B

The first total synthesis of the marine steroid alkaloid plakinamine B (1) was accomplished in seven steps starting from known aldehyde 3. Key steps in this synthesis are the attachment of a vinylpyridine side chain by an aldol reaction, a chemoselective reduction of a pyridinium salt to a vinyl tetrahydropyridine, and the introduction of the 3α-methylamino group under Mitsunobu conditions. Plakinamine B and some of its precursors with amino or pyridinium side chains show significant antimicrobial activities.     

Polymer Chain Conformation on Deuterated Polystyrene Nanoparticles Investigated by SANS

We previously reported that grafted polystyrene (PS) chains on silica nanoparticles at a low grafting density show similar conformations to free PS chains in the same solvent, THF (diameter ?50 nm, Colloid.poly.Sci. (2013), 291, 9, 2087–2099). As an extension of our previous study we choose an organic nanoparticle (deuterated polystyrene, dPS) instead of inorganic nanoparticle to see the impact of the substrate material on chain conformation. Additionally, a wider range of molecular weights were prepared to investigate the conformation feature of grafted PS chains more in detail. Small angle neutron scattering (SANS) experiments were performed to characterize PS grafted dPS particles in good solvent condition, with deuterated toluene and deuterated THF as solvent. To get insight into the conformation of the grafted PS layer we apply a scaling law describing the dimension of free PS polymer in good solvent condition to the obtained thickness of the grafted PS layer. We find an overall agreement with the scaling law where the thickness of the grafted PS layer is slightly larger than 2R_g of the free polymer chains in the respective solvent giving hint for semi dilute polymer brush (SDPB) situation.     

Dimethocaine,a synthetic cocaine analogue: studies on its in-vivo metabolism and its detectability in urine by means of a rat model and liquid chromatography–linear ion-trap (high-resolution) mass spectrometry

Dimethocaine (DMC, larocaine), a synthetic derivative of cocaine, is a widely distributed “legal high” consumed as a “new psychoactive substance” (NPS) without any safety testing, for example studies of metabolism. Therefore, the purpose of this work was to study its in-vivo and in-vitro metabolism by use of liquid chromatography–(high resolution) mass spectrometry (LC–HRMS ⁿ ). DMC was administered to male Wistar rats (20 mg kg^?1) and their urine was extracted either by solid-phase extraction after enzymatic cleavage of conjugates or by use of protein precipitation (PP). The metabolites were separated and identified by LC–HRMS ⁿ . The main phase I reactions were ester hydrolysis, deethylation, hydroxylation of the aromatic system, and a combination of these. The main phase II reaction was N-acetylation of the p-aminobenzoic acid part of the unchanged parent compound and of several phase I metabolites. The metabolites identified were then used for identification of DMC in rat urine after application of a common user’s dose. By use of GC–MS and LC–MS ⁿ standard urine-screening approaches (SUSAs), DMC and its metabolites could be detected in the urine samples.     

Studies on the metabolism and the detectability of 4-methyl-amphetamine and its isomers 2-methyl-amphetamine and 3-methyl-amphetamine in rat urine using GC-MS and LC-(high-resolution)-MS n

4-Methyl-amphetamine (1-(4-methylphenyl)propane-2-amine; 4-MA) and its isomers 2-methyl-amphetamine (2-MA) and 3-methyl-amphetamine (3-MA) belong to the group of amphetamine-type stimulants and of new psychoactive substances. Several studies showed similar potencies in releasing noradrenalin and dopamine, but higher potencies in releasing serotonin than amphetamine. In March 2013, the EU Council decided on an EU-wide control based on the European Monitoring Centre for Drugs and Drug Addiction risk assessment report documenting that 4-MA was sold as amphetamine on the illicit market and detected in several fatal cases. Therefore, 4-MA and its isomers should be covered by drug testing in clinical and forensic toxicology. The aims of the presented work were to study the metabolism and detectability of each isomer in urine samples. For metabolism studies, rat urine samples were isolated by solid-phase extraction without and after enzymatic cleavage of conjugates. The phase I metabolites were separated and identified after acetylation by gas chromatography–mass spectrometry (GC-MS) and/or liquid chromatography–high resolution-linear ion trap mass spectrometry (LC-HR-MS ⁿ ) and the phase II metabolites by LC-HR-MS ⁿ . From the identified phase I and II metabolites, the following main metabolic pathways were deduced: aromatic hydroxylation, hydroxylation of the phenylmethyl group followed by oxidation to the corresponding carboxylic acid, hydroxylation of the side chain, and glucuronidation and/or sulfation of the hydroxy and carboxy groups. CYP2D6 was involved in the aromatic hydroxylation. Finally, the intake of a commonly used dose of the MAs could be confirmed in rat urine using the authors’ GC-MS and the LC-MS ⁿ standard urine screening approaches. Differentiation of the isomers to confirm the intake of a specific isomer was possible with an additional workup in rat urine.