New aryl ethynylene substituted silicon-centered molecules

The reactions of substituted dichlorosilane monomers,Cl₂SiRR′, with two equivalents of lithium aryl acetylide(1), LiC ≡ C-4-C₆H₄-Ph, afford RR′Si(C ≡ C-4-C₆H₄-Ph)₂ (6: R,R′ =CH₃; 7: R = CH₃, R′ = CH=CH₂; 8: R,R′ = Ph). An isomeric mixture of meso, (R,R)- and (S,S)-Bis[2-(N,N-dimethylaminomethyl)ferrocenyl]dichlorosilane (5) was used as starting chlorosilyl compound for reaction with LiC ≡ C-4-C₆H₄-Ph to give (FcN)₂Si(C ≡ C-4-C₆H₄-Ph)₂ (9). A detailedcharacterization of 6, 7, 8 and 9 has been carried out by ¹H-NMR, ¹³C-NMR, ²⁹Si-NMR, IR and UV-VIS spectroscopy. The crystal structure of 9 has been determined by X-ray diffraction analysis.     

Heterologous expression of a myxobacterial natural products assembly line in pseudomonads via red/ET recombineering

Natural products of microbial origin are widely used as pharmaceuticals and in agrochemistry. These compounds are often biosynthesized by multifunctional megasynthetases whose genetic engineering and heterologous expression offer considerable promise, especially if the natural hosts are genetically difficult to handle, slow growing, unculturable, or even unknown. We describe a straightforward strategy that combines the power of advanced DNA engineering (recombiogenic cloning) in Escherichia coli with the utility of pseudomonads as the heterologous host for the analysis and mutagenesis of known and unknown secondary metabolite pathways. The myxochromide S biosynthetic gene cluster from Stigmatella aurantiaca was rebuilt and engineered in E. coli to contain the elements required for expression in pseudomonads. The successful production in Pseudomonas putida, at unprecedented levels, demonstrates the feasibility of the new approach to the analysis and mutagenesis of these important pathways.     

Polymer-assisted dithane hydrolysis with minimum workup

The first solid-phase-assisted protocol for the hydrolysis of dithioacetals is described using three different functionalized ion exchange resins. The hydrolysis and the purification proceed under milder conditions than common homogeneously employed reagents so that very reactive carbonyl compounds can be prepared.     

Nickel electrodes as a cheap and versatile platform for studying structure and function of immobilized redox proteins

Practical use of many bioelectronic and bioanalytical devices is limited by the need of expensive materials and time consuming fabrication. Here we demonstrate the use of nickel electrodes as a simple and cheap solid support material for bioelectronic applications. The naturally nanostructured electrodes showed a surprisingly high electromagnetic surface enhancement upon light illumination such that immobilization and electron transfer reactions of the model redox proteins cytochrome b₅ (Cyt b₅) and cytochrome c (Cyt c) could be followed via surface enhanced resonance Raman spectroscopy. It could be shown that the nickel surface, when used as received, promotes a very efficient binding of the proteins upon preservation of their native structure. The immobilized redox proteins could efficiently exchange electrons with the electrode and could even act as an electron relay between the electrode and solubilized myoglobin. Our results open up new possibility for nickel electrodes as an exceptional good support for bioelectronic devices and biosensors on the one hand and for surface enhanced spectroscopic investigations on the other hand.     

On Albanese and Picard 1-motives with $${\mathbb{G}_a}$$ -factors

We construct Laumon-1-motives Pic⁺_a(X), Alb^-_a(X), Pic^-_a(X){{\rm Pic}^+_a(X), {\rm Alb}^-_a(X), {\rm Pic}^-_a(X)}, and Alb⁺_a(X){{\rm Alb}^+_a(X)} associated to an algebraic variety X with complete singular locus, whose associated étale (Deligne-)1-motives coincide with Picard and Albanese motives constructed by Barbieri Viale and Srinivas.     

Improved phase separation in polymer solar cells by solvent blending

The effect of solvent blending on the performance of an anthracene‐containing poly(p‐phenylene‐ethynylene)‐alt‐poly(p‐phenylene‐vinylene) backbone‐based donor polymer with asymmetrically substituted branched 2‐ethylhexyloxy and methyloxy side‐chains in bulk heterojunction solar cells is reported. This copolymer yields relatively high open‐circuit voltages with fullerene‐based electron acceptors. We systematically studied the thin‐film blend morphology and solar cell performance as a function of solvent composition (chlorobenzene to chloroform ratio) and polymer to [6,6]‐phenyl C61‐butyric acid methylester (PCBM) ratio. We combined photophysical investigations with atomic force microscopy and grazing incidence wide‐angle X‐ray scattering to elucidate the solid‐state morphology in thin films. In the investigated polymer system, the blend morphology becomes independent of the supporting solvent for high PCBM concentrations. Deposition from solvent blends rather than from pure chlorobenzene facilitates the beneficial phase separation between polymer and PCBM, leading to improved charge transport properties (short‐circuit currents) at lower PCBM concentrations. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013, 51, 868–874