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News Article | April 25, 2017
Site: www.eurekalert.org

Generation and photochemical utilization of light are two of the most significant fundamental aspects of technological developments that will shape society, politics, science and the economy in the future. From these can be derived energy-saving concepts in display technology, in the field of solar energy and in the efficient, light-powered syntheses of value-added products as well as in innovative approaches to the use of materials in sensor technology, imaging, and phototherapy. "There is no other class of substances that offers a wider range of design options capable of meeting the demands of these diverse applications than molecular metal complexes," explained Professor Katja Heinze of the Institute of Inorganic Chemistry and Analytical Chemistry at Johannes Gutenberg University Mainz (JGU). Heinze coordinates the new Priority Program "Light-controlled reactivity of metal complexes" (LCRMC) to be funded by the German Research Foundation (DFG). The supraregional DFG Priority Program will commence its work in 2018 and will be funded by the DFG for an anticipated six years. "So far, only a fraction of the scientific and technological potential of photoactive metal complexes has been exploited. The preparation of completely new classes of metal complexes and the investigation of the energy profiles of electronically excited states should enable us to obtain more extensive fundamental insights into this group of substances. This will pave the way for the development of innovative, high performance materials for a range of applications in medicine, sensor technology, display technology, chemical synthesis, and the conversion of sunlight to power," added Heinze. The objective of the LCRMC Priority Program is to join the synthetic, spectroscopic, and theoretical expertise and methodological infrastructure that is currently dispersed among various groups in Germany. The call for proposals of the innovative and highly interdisciplinary LCRMC Priority Program will be announced by the German Research Foundation.


Leifert A.,Institute of Inorganic Chemistry | Pan Y.,RWTH Aachen | Kinkeldey A.,RWTH Aachen | Schiefer F.,Institute of Inorganic Chemistry | And 7 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2013

Understanding the mechanism of toxicity of nanomaterials remains a challenge with respect to both mechanisms involved and product regulation. Here we show toxicity of ultrasmall gold nanoparticles (AuNPs). Depending on the ligand chemistry, 1.4-nm-diameter AuNPs failed electrophysiology-based safety testing using human embryonic kidney cell line 293 cells expressing human ether-á-go-go- Related gene (hERG), a Food and Drug Administration- established drug safety test. In patch-clamp experiments, phosphine-stabilized AuNPs irreversibly blocked hERG channels, whereas thiol-stabilized AuNPs of similar size had no effect in vitro, and neither particle blocked the channel in vivo. We conclude that safety regulations may need to be reevaluated and adapted to reflect the fact that the binding modality of surface functional groups becomes a relevant parameter for the design of nanoscale bioactive compounds.


Lignos I.,ETH Zurich | Protesescu L.,Institute of Inorganic Chemistry | Protesescu L.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Stavrakis S.,ETH Zurich | And 7 more authors.
Chemistry of Materials | Year: 2014

We describe the realization of a droplet-based microfluidic platform for the controlled and reproducible synthesis of lead chalcogenide (PbS, PbSe) nanocrystal quantum dots (QDs). Monodisperse nanocrystals were synthesized over a wide range of experimental conditions, with real-time assessment and fine-tuning of material properties being achieved using NIR fluorescence spectroscopy. Importantly, we show for the first time that real-time monitoring of the synthetic process allows for rapid optimization of reaction conditions and the synthesis of high quality PbS nanocrystals, emitting in the range of 765-1600 nm, without any post-synthetic processing. The segmented-flow capillary reactor exhibits stable droplet generation and reproducible synthesis of PbS nanocrystals with high photoluminescence quantum yields (28%) over extended periods of time (3-6 h). Furthermore, the produced NIR-emitting nanoparticles were successfully used in the fabrication of Schottky solar cells, exhibiting a power conversion efficiency of 3.4% under simulated AM 1.5 illumination. Finally, the droplet-based microfluidic platform was used to synthesize PbSe nanocrystals having photoluminescence peaks in the range of 860-1600 nm, showing the exceptional control and stability of the reactor. © 2014 American Chemical Society.


Zelenka K.,Institute of Inorganic Chemistry | Borsig L.,University of Zürich | Alberto R.,Institute of Inorganic Chemistry
Bioconjugate Chemistry | Year: 2011

To target the nucleus of specific cells, trifunctional radiopharmaceuticals are required. We have synthesized acridine orange derivatives which comprise an imidazole-2-carbaldehyde function for coordination to the [Re(CO) 3]+ or [ 99mTc(CO) 3]+ core. Upon coordination, this aldehyde is activated and rapidly forms imines with amines from biological molecules. This metal-mediated imine formation allows for the conjugation of a nuclear targeting portion with a specific cell receptor binding function directly on the metal. With this concept, we have conjugated the acridine orange part to a bombesin peptide directly on the 99mTc core and in one step. In addition, a linker containing an integrated disulfide has been coupled to bombesin. LC/MS study showed that the disulfide was reductively cleaved with a 60 min half-life time. This concept enables the combination of a nucleus targeting agent with a specific cell receptor molecule directly on the metal without the need of separate conjugation prior to labeling, thus, a modular approach. High uptake of the BBN conjugate into PC-3 cells was detected by fluorescence microscopy, whereas uptake into B16BL6 cells was negligible. © 2011 American Chemical Society.


Koppenol W.H.,Institute of Inorganic Chemistry | Stanbury D.M.,Auburn University | Bounds P.L.,Institute of Inorganic Chemistry
Free Radical Biology and Medicine | Year: 2010

We use published Gibbs energies of formation and equilibrium constants to determine electrode potentials for the partially reduced intermediates along the pathway of reduction of dioxygen to water, as well as of ozone and singlet dioxygen. The results are summarized in an oxidation state (Frost) diagram. Our review of the literature on electrode potentials leads us to revise values for the O2/O2•- couple to E°(O2g/O2•-)=-0.35±0.02V and E°(O2aq/O2•-)=-0.18±0.02V from -0.33 and -0.16V, respectively. Other electrode potentials (pH 7) for the radical species covered are E°′(O3g/O3•-)=+0.91V, E°′(HO2•, H+/H2O2)=+1.05V, E°′(H2O2, H+/HO•, H2O)=+0.39V, and E°′(HO•, H+/H2O)=+2.31V. © 2010 Elsevier Inc.


Kovalenko M.V.,Institute of Inorganic Chemistry | Kovalenko M.V.,Empa - Swiss Federal Laboratories for Materials Science and Technology
Chimia | Year: 2013

This account highlights our recent and present activities dedicated to chemical synthesis and applications of inorganic nanostructures. In particular, we discuss the potential of metal amides as precursors in the synthesis of metallic and semiconductor nanocrystals. We show the importance of surface chemical functionalization for the emergence of collective electronic properties in nanocrystal solids. We also demonstrate a new kind of long-range ordered, crystalline matter comprising colloidal nanocrystals and atomically defined inorganic clusters. Finally, we point the reader's attention to the high potential benefits of size- and shapetunability of nanocrystals for achieving higher performance of rechargeable Li-ion battery electrodes. © Schweizerische Chemische Gesellschaft.


Widenmeyer M.,University of Stuttgart | Niewa R.,University of Stuttgart | Hansen T.C.,Laue Langevin Institute | Kohlmann H.,Institute of Inorganic Chemistry
Zeitschrift fur Anorganische und Allgemeine Chemie | Year: 2013

In order to perform real-time studies of solid-gas reactions involving light elements such as hydrogen and nitrogen, gas pressure and gas flow cells were developed for in situ neutron powder diffraction. The gas pressure cell is based on a sapphire single crystal tube as a sample holder and provides high quality diffraction patterns with very low background up to 16.0 MPa hydrogen (deuterium) gas pressure and temperatures up to 400 °C. The gas flow cell contains a silica tube as sample container and is optimized for flowing ammonia as reaction gas. While it produces higher background owing to the silica, it allows much higher temperatures of up to 750 °C to be used. For both cells heating is realized contactless and without any contribution to the diffraction patterns by two lasers and so high-quality diffraction data allowing for a detailed Rietveld analysis can be collected on D20 (Institute Laue-Langevin) with a one minute time resolution. Examples are presented demonstrating the potential of the in situ gas cells, ranging from the nitridation of vanadium and iron powders with flowing ammonia, to the deuteration of palladium and the hydrogen storage material LaNi5. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Schaal P.A.,Institute of Inorganic Chemistry | Besmehn A.,Forschungszentrum Juelich GmbH | Maynicke E.,RWTH Aachen | Noyong M.,Institute of Inorganic Chemistry | And 2 more authors.
Langmuir | Year: 2012

We report the formation of thiol nanopatterns on SAM covered silicon wafers by converting sulfonic acid head groups via e-beam lithography. These thiol groups act as binding sites for gold nanoparticles, which can be enhanced to form electrically conducting nanostructures. This approach serves as a proof-of-concept for the combination of top-down and bottom-up processes for the generation of electrical devices on silicon. © 2012 American Chemical Society.


Marthala V.R.R.,University of Stuttgart | Hunger M.,University of Stuttgart | Kettner F.,Institute of Inorganic Chemistry | Krautscheid H.,Institute of Inorganic Chemistry | And 3 more authors.
Chemistry of Materials | Year: 2011

Large crystals of all-silica, aluminum-, and boron-containing ferrierite zeolites were synthesized using a solvothermal synthesis method and a fluoride medium. Alkylamines, namely, propylamine, butylamine, and pentylamine were employed as templates in the syntheses. The products were characterized by powder X-ray diffraction (XRD), inductively coupled plasma-optical emission spectrometry (ICP-OES), thermogravimetric analysis (TGA), elemental (CHN) analyses, scanning electron microscopy (SEM), N2-adsorption, and 1H, 11B, 27Al, as well as 29Si MAS NMR spectroscopy. The 27Al and 11B MAS NMR spectroscopic investigations revealed that aluminum and boron were successfully incorporated into the FER-type framework. SEM indicated the occurrence of crystals with a size of up to about 600 μm. Furthermore, for all-silica and boron-containing ferrierite zeolites, the shape, size, and thickness of the crystals could be controlled by increasing the chain length of the alkyl group in the alkylamine and the crystallization time. Aluminum-containing ferrierite zeolites could be synthesized with a rectangular morphology exclusively. Observation of transient guest profiles during methanol uptake by means of IR microscopy exemplifies the possibility of directly observing diffusion anisotropy in FER-type frameworks. © 2011 American Chemical Society.


Orlov A.,Institute of Inorganic Chemistry | Grabis J.,Institute of Inorganic Chemistry
High Temperature Material Processes | Year: 2011

The preparation of fine MoSi2 and MoSi2 - Si 3N 4 composite powders with specific surface area of 16-33 and 30-41 m 2 /g respectively by evaporation of Si and Mo raw powder mixtures or coarse grained MoSi2 in radio frequency inductively coupled nitrogen plasma flow was investigated. Specific surface area of obtained powders as well as content of MoSi 2 modifications, Si 3N 4 and extra phases Mo 5 Si 3, Si depends on the raw powder feeding rate, the cooling gas flow rate and the composition of raw mixtures. The shape of the product particles was spherical for MoSi 2 and both spherical and whiskers for composites. © 2011 by Begell House, Inc.

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