Silanetriols as in vitro inhibitors for AChE

AbstractThree stable silanetriols with increasing steric protection of the silicon atom have been tested for inhibition of acetylcholinesterase (AChE). For all tested silanetriols we found reversible inhibition of the AChE activity at a 100μM concentration. The highest inhibition rate was found for the sterically least hindered cyclohexylsilanetriol with 45% inhibition relative to galanthamine hydrobromide for which an IC50 value of 121±3μM was determined as well. The cytotoxicity of the silanetriols used was found to be negligible at concentrations relevant for inhibition

Optimized Synthesis of Tetrafluoroterephthalic Acid: A Versatile Linking Ligand for the Construction of New Coordination Polymers and Metal-Organic Frameworks

Pure 2,3,5,6-tetrafluoroterephthalic acid (H(2)tfBDC) is obtained in high yields (95%) by reacting 1,2,4,5-tetrafluorobenzene with a surplus (>2 equiv) of n-butyllithium in tetrahydrofuran (THF) and subsequent carbonation with CO2 without any extensive purification procedure. A single crystal X-ray structure analysis of H2tfBDC (1) confirms former data obtained for a deuterated sample (P (1) over bar, Z = 1). Recrystallization from water/acetone leads to single crystals of H(2)tfBDC center dot 2H(2)O (2, P2(1)/c, Z. 2), where an extensive hydrogen bonding network is found. By reacting H2tfBDC with an aqueous ammonia solution, single crystals of (NH4)(2)tfBDC (3, C2/m, Z. 2) are obtained. 3 is thermally stable up to 250 degrees C and shows an enhanced solubility in water compared to H(2)tfBDC. Monosubstituted 2,3,5,6-tetrafluorobenzoic acid (H(2)tfBC, 4) is obtained by reacting 1,2,4,5-tetrafluorobenzene with stoichiometric amounts (1 equiv) of n-butyllithium in THF. Its crystal structure (Fdd2, Z = 16) shows dimeric units as characteristic structural feature

Moving on from Silicon to the Heavier Tetrels: Germyl- and Stannyl-Substituted Phosphole Derivatives

Germyl- and stannyl-substituted phospholes have been prepared and isolated. The increased reactivity of the tetrel carbon bond requires increased effort in purification by initial transformation to the chalcogen derivatives and subsequent reduction to the phosphole after subsequent to chromatographic purification for the germanium derivative. The photophysical properties of the germyl phosphole are comparable to that of its silyl analogue, whereas the stannyl phospholes turned out to be nonluminescent. All isolated compounds have been characterized by NMR spectroscopy, mass spectrometry, and elemental analysis. Furthermore, single-crystal X-ray diffraction and density functional theory (DFT) calculations have been performed on selected compounds

Tailoring the Fe → Pd interaction in cationic Pd(ii) complexes via structural variation of the ligand scaffold of sterically demanding dppf-analogs and their P,N-counterparts

Two 1,1′-azaphospha substituted dppf-analogues Fc′(NMe2)(PPh2) (Ph = C6H5, Fc′ = 1,1′-ferrocenediyl, 3a) and Fc′(NMe2)(PMes2) (Mes = 2,4,6-Me3C6H2, 3b) have been prepared, via reductive amination, followed by salt-metathesis (of 2), starting from 1,1′-azabromoferrocene 1. Their donor properties have been explored using heteronuclear NMR spectroscopy based on their 1JP–Se coupling, and the formation of PdCl2-complexes in comparison to a set of related dppf analogs with gradual steric variation, such as Fc′(PMes2)(PPh2) (5) and Fc′(PMes2)(PtBu2) (6). Chloride abstraction from these complexes, namely Fc′(PMes2)(PPh2)·PdCl2 (7), Fc′(PMes2)(PtBu2)·PdCl2 (8), and [Fc′(NMe2)(PPh2)]2·PdCl2 (9) using AgSbF6 produced the corresponding cationic Pd(II) complexes [Fc′(PMes2)(PtBu2)·PdCl][SbF6] (10), [Fc′(PPh2)(NMe2)·PdCl][SbF6]2 (11) and [Fc′(PPh2)(NMe2)·Pd(PPh2C5H5)][SbF6]2 (12) featuring Fe → Pd interactions. Variation of the counter anion by coordination of 3a to a chloride-free Pd(II) source furnished [Fc′(PPh2)(NMe2)·Pd(PPh3)][BF4]2 (13), [Fc′(PPh2)(NMe2)·Pd(PPh2)Fc′(NMe2)][BF4]2 (14), and [Fc′(PPh2)(NMe2)·PdP(p-OMe-C6H4)3][BF4]2 (15) with similar Fe → Pd interactions. Comparison with previously reported diphospha- and azaphospha- counterparts, revealed that 10 and 11 display the shortest and 15 the longest Fe–Pd bond, within their ligand scaffold congeners. DFT calculations performed on compounds 10–15 were further able to verify their intrinsic structural features and trends and shed light on the nature of the Fe → Pd bonding interactions which are furthermore consistent with CV measurements

Gradual Donor Stabilization of a Transient Ferrocene Bridged Bisphosphanyl Phosphenium Cation

A transient phosphenium cation embedded into a [3]ferrocenophane scaffold was formed via chloride abstraction. The cation has been trapped with phosphane, carbene, and silylene donors resulting in stable adducts or bond activation of the ferrocenophane bridge. In the absence of donors, dimerization of the phosphenium cation to the corresponding dication is observed or P–C bond activation with migration of a substituent leading to a putative phosphoniodiphosphene. Using 1,3-di-tert-butylimidazol-2-silylene as the donor, further reaction of the initially formed chlorosilane leads to activation of a P–P bond of the ferrocenophane scaffold with ring expansion of the ansa-bridge. The donor formation and bonding situation are investigated by density functional theory calculations as well as experimental methods (e.g., NMR spectroscopy and X-ray crystallography)

SolNet:PhD-scholarships and courses on solar heating

AbstractSolNet, founded in 2006, is the first coordinated International PhD education program on Solar Thermal Engineering. The SolNet network is coordinated by the Institute of Thermal Engineering at Kassel University, Germany. The network offers PhD courses on solar heating and cooling, conference-accompanying Master courses, placements of internships, and PhD scholarship projects. A new scholarship project, “SHINE”, will be launched in autumn 2013 in the frame work of the Marie Curie program of the European Union (Initial Training Network, ITN). 13 PhD-scholarships on solar district heating, solar heat for industrial processes, as well as sorption stores and materials will be offered, starting in December 2013. Additionally, the project comprises a training program with five PhD courses and several workshops on solar thermal engineering that will be open also for other PhD students working in the field. The research projects will be hosted by six different universities and five companies from all over Europe

Bis-[3]Ferrocenophanes with Central >E-E'<Bonds (E, E'=P, SiH) : Preparation, Properties, and Thermal Activation

Cover profile:10.1002/open.201900279.Invited for this month's cover picture are the groups of Professors Rudolf Pietschnig at the University of Kassel, Professor Dietrich Gudat at the University of Stuttgart and Professor Laszlo Nyulaszi at the Budapest University of Technology and Economics. The cover picture shows the thermally induced homolytic cleavage of the central P-P bond in a phosphorus-rich bis-ferrocenophane furnishing P-centered radicals (as evidenced by the computed spin-density highlighted in blue). The central P-6 unit in the title compound is a structural analog of the connecting unit in Hittorf's violet phosphorus, which links the orthogonally arranged tubular entities. A portrait of the German physicist Johann Wilhelm Hittorf is included. Read the full text of their Full Paper at 10.1002/open.201900182.Peer reviewe