Molekularer Magnetismus von mono- und heteropolymetallischen Verbindungen basierend auf Bispidinkomplexen

Diese Arbeit zeigt die Vielfältigkeit der Bispidine-Liganden als Bausteine in molekularen Magneten. Durch die Reaktion von Hexacyanometallaten mit Bispidinkomplexen konnte eine Reihe von heterotrinuklearen Verbindungen hergestellt werden. Diese Verbindungen wurden durch experimentelle Messungen und sorgfältige theoretische Betrachtungen untersucht. Die theoretische Analyse beinhaltet drei Modelle zur Simulation der experimentellen Daten. Das einfache Modell 1 basiert auf einem isotropen Austausch-Hamiltonian. Das Modell 2 bezieht auch die Aufspaltung des 2T2g-Grundzustands des Hexacyanoferrat(III)zentrums in die theoretische Betrachtung mit ein. Das Modell 3 wurde benutzt, wenn die experimentellen Daten das Auftreten einer starken Anisotropie zeigen und das Modell 2 aufgrund fehlender Strukturdaten nicht eingesetzt werden konnte. Durch die Verwendung des Modells 2 konnte gezeigt werden, dass eine Abweichung von der perfekten Oktaedergeometrie des Hexacyanoferrat(III)zentrums um wenige Grad eine Verringerung der magnetischen Anisotropie um eine Größenordnung zur Folge hat. Der zweite Teil der vorliegenden Arbeit beschäftigt sich mit mononuklearen Bispidinkomplexen als mögliche Einzelmolekülmagnete. Der Bispidinligand verursacht eine axiale Verzerrung des Metallzentrums, was eine Voraussetzung für das Auftreten einer Nullfeldaufspaltung darstellt und somit die Möglichkeit einer langsamen Relaxation der Magnetisierung eröffnet. Der letzte Teil beschäftigt sich mit einem neuen Bispidinligand, der durch eine Bipyridin Koordinationsstelle die Möglichkeit schafft, Fotoaktivität in eine Verbindung einzuführen. Der Ligand L3 besitzt außer dem Bipyridin-Substituenten eine weitere Koordinationsstelle in Form eines substituierten Bispidingerüsts. Die Untersuchungen des Fluoreszenzverhaltens und der magnetischen Eigenschaften durch ESR-Spektroskopie zeigen einen Energietransfer zwischen einem an das Bipyridin koordinierten Rutheniumion und einem durch den Bispidinbereich komplexierten Kupferion

Optimization and evaluation of variability in the programming window of a flash cell with molecular metal-oxide storage

We report a modeling study of a conceptual nonvolatile memory cell based on inorganic molecular metal-oxide clusters as a storage media embedded in the gate dielectric of a MOSFET. For the purpose of this paper, we developed a multiscale simulation framework that enables the evaluation of variability in the programming window of a flash cell with sub-20-nm gate length. Furthermore, we studied the threshold voltage variability due to random dopant fluctuations and fluctuations in the distribution of the molecular clusters in the cell. The simulation framework and the general conclusions of our work are transferrable to flash cells based on alternative molecules used for a storage media

Encapsulation of a {Cu16} cluster containing four [Cu4O4] cubanes within an isopolyoxometalate {W44} cluster

We report a {Cu16} embedded within a {W44} cluster containing four cubane-like [Cu4O4] units within an isopolyoxotungstate (isoPOT) in a {Na4Cu4[(H2W11O38) (CH3COO)(OH)3]}4·88H2O (1) and a polyanion Cu-linked {W11} chain Na6Cu2[(H2W11O38)(CH3COO)(OH)]·26H2O (2). Electronically, the redox properties show that both compounds 1 and 2 undergo irreversible reductions resulting in the demetalation of the compounds, whilst the magnetic behavior of 1 and 2 shows a weak antiferromagnetic and a stronger ferromagnetic coupling, respectively

Hybrid Amperometric and Potentiometric Sensing Based on a CMOS ISFET Array

Potentiometry and amperometry are some of the most important techniques for electroanalytical applications. Integrating these two techniques on a single chip using CMOS technology paves the way for more analysis and measurement of chemical solutions. In this paper, we describe the integration of electrode transducers (amperometry) on an ion imager based on an ISFET array (potentiometry). In particular, this integration enables the spatial representation of the potential distribution of active electrodes in a chemical solution under investigation

Comparison between bulk and FDSOI POM flash cell: a multiscale simulation study

In this brief, we present a multiscale simulation study of a fully depleted silicon-on-insulator (FDSOI) nonvolatile memory cell based on polyoxometalates (POMs) inorganic molecular clusters used as a storage media embedded in the gate dielectric of flash cells. In particular, we focus our discussion on the threshold voltage variability introduced by random discrete dopants (random dopant fluctuation) and by fluctuations in the distribution of the POM molecules in the storage media (POM fluctuation). To highlight the advantages of the FDSOI POM flash cell, we provide a comparison with an equivalent cell based on conventional (BULK) transistors. The presented simulation framework and methodology is transferrable to flash cells based on alternative molecules used as a storage media

A 16 x 16 CMOS amperometric microelectrode array for simultaneous electrochemical measurements

There is a requirement for an electrochemical sensor technology capable of making multivariate measurements in environmental, healthcare, and manufacturing applications. Here, we present a new device that is highly parallelized with an excellent bandwidth. For the first time, electrochemical cross-talk for a chip-based sensor is defined and characterized. The new CMOS electrochemical sensor chip is capable of simultaneously taking multiple, independent electroanalytical measurements. The chip is structured as an electrochemical cell microarray, comprised of a microelectrode array connected to embedded self-contained potentiostats. Speed and sensitivity are essential in dynamic variable electrochemical systems. Owing to the parallel function of the system, rapid data collection is possible while maintaining an appropriately low-scan rate. By performing multiple, simultaneous cyclic voltammetry scans in each of the electrochemical cells on the chip surface, we are able to show (with a cell-to-cell pitch of 456 μm) that the signal cross-talk is only 12% between nearest neighbors in a ferrocene rich solution. The system opens up the possibility to use multiple independently controlled electrochemical sensors on a single chip for applications in DNA sensing, medical diagnostics, environmental sensing, the food industry, neuronal sensing, and drug discovery

Elucidating the paramagnetic interactions of an inorganic–organic hybrid radical-functionalized Mn-Anderson cluster

A family of six polyoxometalate-based magnetic compounds were synthesized by anchoring N-oxide type TEMPO radicals onto an Anderson type polyoxometalate cluster. The complexes were structurally characterised by single crystal X-ray diffraction and the intramolecular paramagnetic interactions between TEMPO radicals and Mn ions of the resulting hybrids were investigated in detail by electron paramagnetic resonance and the Evans NMR method

Effective storage of electrons in water by the formation of highly reduced polyoxometalate clusters

Aqueous solutions of polyoxometalates (POMs) have been shown to have potential as high-capacity energy storage materials due to their potential for multi-electron redox processes, yet the mechanism of reduction and practical limits are currently unknown. Herein, we explore the mechanism of multi-electron redox processes that allow the highly reduced POM clusters of the form {MO3}y to absorb y electrons in aqueous solution, focusing mechanistically on the Wells–Dawson structure X6[P2W18O62], which comprises 18 metal centers and can uptake up to 18 electrons reversibly (y = 18) per cluster in aqueous solution when the countercations are lithium. This unconventional redox activity is rationalized by density functional theory, molecular dynamics simulations, UV–vis, electron paramagnetic resonance spectroscopy, and small-angle X-ray scattering spectra. These data point to a new phenomenon showing that cluster protonation and aggregation allow the formation of highly electron-rich meta-stable systems in aqueous solution, which produce H2 when the solution is diluted. Finally, we show that this understanding is transferrable to other salts of [P5W30O110]15– and [P8W48O184]40– anions, which can be charged to 23 and 27 electrons per cluster, respectively

B lymphocytes trigger monocyte mobilization and impair heart function after acute myocardial infarction.

Acute myocardial infarction is a severe ischemic disease responsible for heart failure and sudden death. Here, we show that after acute myocardial infarction in mice, mature B lymphocytes selectively produce Ccl7 and induce Ly6C(hi) monocyte mobilization and recruitment to the heart, leading to enhanced tissue injury and deterioration of myocardial function. Genetic (Baff receptor deficiency) or antibody-mediated (CD20- or Baff-specific antibody) depletion of mature B lymphocytes impeded Ccl7 production and monocyte mobilization, limited myocardial injury and improved heart function. These effects were recapitulated in mice with B cell-selective Ccl7 deficiency. We also show that high circulating concentrations of CCL7 and BAFF in patients with acute myocardial infarction predict increased risk of death or recurrent myocardial infarction. This work identifies a crucial interaction between mature B lymphocytes and monocytes after acute myocardial ischemia and identifies new therapeutic targets for acute myocardial infarction.This work was supported by Inserm, British Heart Foundation (Z.M.), European Research Council (Z.M.), Fondation Coeur et Recherche (Z.M., T.S., N.D.), Fondation pour la Recherche Medicale (J.S.S.), European Union Seven Framework programme TOLERAGE (Z.M.), Fondation Leducq transatlantic network (C.J.B., D.T., A.T., J.S.S., Z.M.), National Institutes of Health grants AI56363 and AI057157, and a grant from The Lymphoma Research Foundation (T.F.T).This is the author accepted manuscript. The final version is available from Nature Publishing Group at http://dx.doi.org/10.1038/nm.3284

Novel RuII complexes with bispidine-based bridging ligands: luminescence sensing and photocatalytic properties

New ligands with a bidentate bipyridyl (bpy) and a tetradentate bispidine (bisp) subunit (bipyridyl = 2,2′-bipyridine derivative, bispidine = 3,7-diazabicyclo[3.3.1]nonane derivative) and their heterodinuclear {[Ru(bpy)3]2+-[M(bisp)]2+} complexes (M = Cu2+, Fe2+) were prepared and characterized. The luminescence of the mononuclear RuII complexes (metal-free bisp subunit) is efficiently quenched in presence of CuII. An EPR spectroscopic study reveals thatvisible light irradiation does not alter the oxidation states of the two metal ions in {[Ru(bpy)3]2+-[Cu(bisp)]2+}, i.e. there is energy rather than electron transfer. The heterodinuclear {[Ru(bpy)3]2+-[Cu(bisp)]2+} complex shows a significantphotocatalytic activity in the aziridination of styrene