Dr. rer. nat. Gudrun Scholz

Profil

• Atomarer Wasserstoff als Spinsonde in thermisch und mechanisch aktivierten Materialien

  Quelle ↗

  Zeitraum: 01/2000 - 02/2005 Projektleitung: Dr. rer. nat. Gudrun Scholz

• Untersuchung der Einflußfaktoren bei der Synthese klarer MgF2-Sole für die Herstellung transparenter, niedrigbrechender Schichten

  Quelle ↗

  Förderer: Wirtschaftsunternehmen / gewerbliche Wirtschaft Zeitraum: 10/2010 - 02/2011 Projektleitung: Dr. rer. nat. Gudrun Scholz

• nanofluor GmbH

  PT

  135 Treffer60.5%
  • Entwicklung von wenig löslichen, homodispers nanoskopischen Metallfluoriden in Zahnzementen, Kompositfüllmaterialien und in Prophylaxepräparaten zum Einsatz im Dentalbereich
    P

    60.5%

• Ionera Technologies GmbH

  PT

  109 Treffer56.2%
  • EU: Monomer Sequence Control in Polymers: Toward Next-Generation Precision Materials (EURO-SEQUENCES)
    P

    56.2%

• Peugeot Citroen Automobiles S.A.

  PT

  110 Treffer56.2%
  • EU: Monomer Sequence Control in Polymers: Toward Next-Generation Precision Materials (EURO-SEQUENCES)
    P

    56.2%

• Bernstein Center for Computational Neuroscience Berlin

  P

  102 Treffer54.6%
  • SFB 1315/2: Mechanismen und Störungen der Gedächtniskonsolidierung: Von Synapsen zur Systemebene
    P

    54.6%
  • DFG-Sachbeihilfe: Aufmerksamkeit und sensorische Integration im aktiven Sehen von bewegten Objekten
    P

    48.3%

• Graphenea S.A.

  PT

  98 Treffer54.5%
  • EU: Bottom-Up Generation of atomicalLy Precise syntheTIc 2D MATerials for High Performance in Energy and Electronic Applications – A Multi-Site Innovative Training Action (ULTIMATE)
    P

    54.5%

• Istituto Italiano di Tecnologia

  P

  100 Treffer54.5%
  • EU: Bottom-Up Generation of atomicalLy Precise syntheTIc 2D MATerials for High Performance in Energy and Electronic Applications – A Multi-Site Innovative Training Action (ULTIMATE)
    P

    54.5%

• International Business Machines Corporation Research GmbH

  PT

  173 Treffer54.5%
  • EU: Bottom-Up Generation of atomicalLy Precise syntheTIc 2D MATerials for High Performance in Energy and Electronic Applications – A Multi-Site Innovative Training Action (ULTIMATE)
    P

    54.5%
  • EU: Simulation in Multiscale Physical and Biological Systems (STIMULATE)
    P

    52.3%

• A.P.E. Research srl

  PT

  130 Treffer54.5%
  • EU: Bottom-Up Generation of atomicalLy Precise syntheTIc 2D MATerials for High Performance in Energy and Electronic Applications – A Multi-Site Innovative Training Action (ULTIMATE)
    P

    54.5%
  • Integrated Self-Assembled SWITCHable Systems and Materials: Towards Responsive Organic Electronics – A Multi-Site Innovative Training Action (iSwitch)
    P

    50.9%

• TechOnYou Srl

  P

  108 Treffer53.6%
  • EU: Hybrid Organic/Inorganic Memory Elements for Integration of Electronic and Photonic Circuitry (HYMEC)
    P

    53.6%

• SpaceTech GmbH

  P

  9 Treffer53.4%
  • Gravitational Wave Observatory Metrology Laser
    P

    53.4%

• Niobium pentoxide nanomaterials with distorted structures as efficient acid catalysts

  2019

  Communications Chemistry · 122 Zitationen · DOI

  Abstract Niobium pentoxides are promising acid catalysts for the conversion of biomass into fuels and chemicals. Developing new synthesis routes is essential for designing niobium pentoxide catalysts with improved activity for specific practical processes. Here we show a synthesis approach in acetophenone, which produces nanostructured niobium pentoxides with varying structure and acidity that act as efficient acid catalysts. The oxides have orthorhombic structures with different extents of distortions and coordinatively unsaturated metal atoms. A strong dependence is observed between the type and strength of the acid sites and specific structural motifs. Ultrasmall niobium pentoxide nanoparticles, which have strong Brønsted acidity, as well as Lewis acidity, give product yields of 96% (3 h, 140 °C, 100% conversion), 85% (3 h, 140 °C, 86% conversion), and 100% (3 h, 110 °C, 100% conversion) in the reactions of furfuryl alcohol, 5-(hydroxymethyl)furfural, and α-angelica lactone with ethanol, respectively.

• Catalytic Hydrodefluorination of Fluoromethanes at Room Temperature by Silylium‐ion‐like Surface Species

  2013

  Angewandte Chemie International Edition · 113 Zitationen · DOI

  'Al'l about F: Aluminum chlorofluoride (ACF) catalyzes the hydrodefluorination, as well as Friedel–Crafts reactions of fluorinated methanes in the presence of Et3SiH. A surface-bound silylium-ion-like species is considered to be a crucial intermediate in achieving the CF bond cleavage.

• Novel Sol–Gel Synthesis of Acidic MgF_2−<i>x</i>(OH)_<i>x</i> Materials

  2008

  Chemistry - A European Journal · 105 Zitationen · DOI

  Novel magnesium fluorides have been prepared by a new fluorolytic sol-gel synthesis for fluoride materials based on aqueous HF. By changing the amount of water at constant stoichiometric amount of HF, it is possible to tune the surface acidity of the resulting partly hydroxylated magnesium fluorides. These materials possess medium-strength Lewis acid sites and, by increasing the amount of water, Brønsted acid sites as well. Magnesium hydroxyl groups normally have a basic nature and only with this new synthetic route is it possible to create Brønsted acidic magnesium hydroxyl groups. XRD, MAS NMR, TEM, thermal analysis, and elemental analysis have been applied to study the structure, composition, and thermal behaviour of the bulk materials. XPS measurements, FTIR with probe molecules, and the determination of N(2)/Ar adsorption-desorption isotherms have been carried out to investigate the surface properties. Furthermore, activity data have indicated that the tuning of the acidic properties makes these materials versatile catalysts for different classes of reactions, such as the synthesis of (all-rac)-[alpha]-tocopherol through the condensation of 2,3,6-trimethylhydroquinone (TMHQ) with isophytol (IP).

• LATERITIC DEEP WEATHERING OF GRANITE

  1973

  Journal of Soil Science · 92 Zitationen · DOI

  Summary Chemical and mineralogical analyses of two representative laterite profiles developed from granite in south‐western Australia have shown that several depth zones defined by particular mineral suites and geochemistry may be recognized. These zones are not simply related to the conventional morphological pallid, mottled, and ferruginous zones. Changes in geochemistry in both profiles can be related to the stability of the major mineral species and to the common isomorphous substitutions occurring in them. Ca, Na, and Mg, which are mainly present in plagioclase feldspars and ferromagnesian minerals, are removed during the earliest stage of alteration of the parent granite. K, Mn, Zn, and residual Ca, Na, Mg, and Sr decrease as microcline and micas alter to kaolin. Al and Fe are most abundant in the surface zones which contain secondary sesquioxide minerals.

• First-order differential equations in chemistry

  2014

  ChemTexts · 85 Zitationen · DOI

• Spectroscopic characterization of crystalline AlF3 phases

  2009

  Journal of Fluorine Chemistry · 77 Zitationen · DOI

• NbF₅–AlF₃ Catalysts: Design, Synthesis, and Application in Lactic Acid Synthesis from Cellulose

  2015

  ACS Catalysis · 74 Zitationen · DOI

  A series of niobium-modified aluminum hydroxide fluorides (denoted Nb@AlF3), prepared via a fluorolytic sol–gel synthesis was investigated for the catalytic one-pot conversion of cellulose to lactic acid. The structure of the new acid catalysts is the result of the dispersion of niobium fluoride in an aluminum hydroxide fluoride matrix. The calcination of the catalysts at a relatively low temperature (350 °C) stabilized this structure. Catalytic performances in terms of lactic acid yields are directly correlated with the niobium content.

• Structural Insights into Aluminum Chlorofluoride (ACF)

  2003

  Inorganic Chemistry · 74 Zitationen · DOI

  The structure of the very strong solid Lewis acid aluminum chlorofluoride (ACF, AlCl(x)F(3-x), x = 0.05-0.3) was studied by IR, ESR, Cl K XANES, (19)F MAS NMR, and (27)Al SATRAS NMR spectroscopic methods and compared with amorphous aluminum fluoride conventionally prepared by dehydration of alpha-AlF(3) x 3H(2)O. The thermal behavior of both compounds was investigated by DTA and XRD. In comparison to ACF, amorphous AlF(3) prepared in a conventional way is not catalytically active for the isomerization reaction of 1,2-dibromohexafluoropropane, which requires a very strong Lewis acid. Both compounds are mainly built up of corner-sharing AlF(6) octahedra forming a random network. The degree of disorder in ACF is higher than in amorphous AlF(3). Terminal fluorine atoms were detected in ACF by (19)F NMR. The chlorine in ACF does not exist as a separate, crystalline AlCl(3) phase. Additionally, chlorine-containing radicals, remaining from the synthesis, are trapped in cavities of ACF. These radicals are stable at room temperature but do not take part in the catalytic reaction.

• Structural evolution of H4PVMo11O40⋅xH2O during calcination and isobutane oxidation: New insights into vanadium sites by a comprehensive in situ approach

  2006

  Journal of Catalysis · 72 Zitationen · DOI

• Is Geometric Frustration-Induced Disorder a Recipe for High Ionic Conductivity?

  2017

  Journal of the American Chemical Society · 70 Zitationen · DOI

  Ionic conductivity is ubiquitous to many industrially important applications such as fuel cells, batteries, sensors, and catalysis. Tunable conductivity in these systems is therefore key to their commercial viability. Here, we show that geometric frustration can be exploited as a vehicle for conductivity tuning. In particular, we imposed geometric frustration upon a prototypical system, CaF₂, by ball milling it with BaF₂, to create nanostructured Ba_1-xCa_xF₂ solid solutions and increased its ionic conductivity by over 5 orders of magnitude. By mirroring each experiment with MD simulation, including "simulating synthesis", we reveal that geometric frustration confers, on a system at ambient temperature, structural and dynamical attributes that are typically associated with heating a material above its superionic transition temperature. These include structural disorder, excess volume, pseudovacancy arrays, and collective transport mechanisms; we show that the excess volume correlates with ionic conductivity for the Ba_1-xCa_xF₂ system. We also present evidence that geometric frustration-induced conductivity is a general phenomenon, which may help explain the high ionic conductivity in doped fluorite-structured oxides such as ceria and zirconia, with application for solid oxide fuel cells. A review on geometric frustration [ Nature 2015 , 521 , 303 ] remarks that classical crystallography is inadequate to describe systems with correlated disorder, but that correlated disorder has clear crystallographic signatures. Here, we identify two possible crystallographic signatures of geometric frustration: excess volume and correlated "snake-like" ionic transport; the latter infers correlated disorder. In particular, as one ion in the chain moves, all the other (correlated) ions in the chain move simultaneously. Critically, our simulations reveal snake-like chains, over 40 Å in length, which indicates long-range correlation in our disordered systems. Similarly, collective transport in glassy materials is well documented [for example, J. Chem. Phys. 2013 , 138 , 12A538 ]. Possible crystallographic nomenclatures, to be used to describe long-range order in disordered systems, may include, for example, the shape, length, and branching of the "snake" arrays. Such characterizations may ultimately provide insight and differences between long-range order in disordered, amorphous, or liquid states and processes such as ionic conductivity, melting, and crystallization.

• Organosilicas with Chiral Bridges and Self-Generating Mesoporosity

  2007

  Chemistry of Materials · 59 Zitationen · DOI

  Amine-functionalized, chiral mesoporous organosilicas were prepared from a rationally designed precursor, which combines the functions of a network builder, a chiral latent functional group, and a porogen in one molecule. The precursors are formed by a convenient enantioselective hydroboration using (S)-monoisopinocampheylborane on an ethylene-bridged silica precursor. These precursors do self-organize when hydrolysis of their inorganic moiety takes place via an aggregation of their organic moiety into hydrophobic domains. After a condensation−ammonolysis sequence mesoporous organosilicas functionalized with chiral amine groups are obtained, with the complete chiral functionalities located at the pore wall surface and therefore accessible to chemical processes. The pore size of the resulting organosilicas can be fine-tuned using different organic moieties attached to the boron group in the first step. While a wormlike arrangement of pores is observed for the pure precursor, common surfactants can be admixed to further control and tailor the resulting mesoporous system. In certain phase ranges, also chiral periodic mesoporous organosilicas can be obtained.

• Local structural orders in nanostructured Al₂O₃prepared by high-energy ball milling

  2002

  Journal of Physics Condensed Matter · 57 Zitationen · DOI

  Nanostructured Al2O3 powders were prepared by high-energy ball milling of corundum. Both the solid state nuclear magnetic resonance spectra of the Al3+ ions and the solid state electron paramagnetic resonance spectra of incorporated Fe3+ ions are governed by noticeable spectral changes dependent on the duration of the mechanical treatment. The quadrupolar parameters of the 27Al nuclei and the zero-field splitting parameters of the Fe3+ ions as well as their statistical distributions were determined as functions of the milling time. Structural changes of the Al2O3 matrix were also followed by powder x-ray diffraction and transmission electron microscopy measurements. Direct relations between the structural disorder as obtained by x-ray data and the spin Hamiltonian parameters of both ions could be established.

• Novel and easy access to highly luminescent Eu and Tb doped ultra-small CaF₂, SrF₂ and BaF₂ nanoparticles – structure and luminescence

  2017

  Dalton Transactions · 54 Zitationen · DOI

  A universal fast and easy access at room temperature to transparent sols of nanoscopic Eu³⁺ and Tb³⁺ doped CaF₂, SrF₂ and BaF₂ particles via the fluorolytic sol-gel synthesis route is presented. Monodisperse quasi-spherical nanoparticles with sizes of 3-20 nm are obtained with up to 40% rare earth doping showing red or green luminescence. In the beginning luminescence quenching effects are only observed for the highest content, which demonstrates the unique and outstanding properties of these materials. From CaF₂:Eu10 via SrF₂:Eu10 to BaF₂:Eu10 a steady increase of the luminescence intensity and lifetime occurs by a factor of ≈2; the photoluminescence quantum yield increases by 29 to 35% due to the lower phonon energy of the matrix. The fast formation process of the particles within fractions of seconds is clearly visualized by exploiting appropriate luminescence processes during the synthesis. Multiply doped particles are also available by this method. Fine tuning of the luminescence properties is achieved by variation of the Ca-to-Sr ratio. Co-doping with Ce³⁺ and Tb³⁺ results in a huge increase (>50 times) of the green luminescence intensity due to energy transfer Ce³⁺ → Tb³⁺. In this case, the luminescence intensity is higher for CaF₂ than for SrF₂, due to a lower spatial distance of the rare earth ions.

• Evaluation of the formation pathways of cocrystal polymorphs in liquid-assisted syntheses

  2014

  CrystEngComm · 53 Zitationen · DOI

  Small but important: the kind of solvent added in liquid-assisted grinding syntheses of cocrystals influences the final product and the reaction rate.

• Structural characterization of amorphous hydrogenated-carbon nitride (aH-CNx) film deposited by CH4/N2 dielectric barrier discharge plasma: 13C, 1H solid state NMR, FTIR and elemental analysis

  2009

  Surface and Coatings Technology · 50 Zitationen · DOI

• Variation of sol–gel synthesis parameters and their consequence for the surface area and structure of magnesium fluoride

  2007

  Journal of Materials Chemistry · 48 Zitationen · DOI

  High surface area MgF2 was prepared by the sol–gel technique from magnesium alkoxides. The influence of different ratios of Mg(OCH3)2 to HF, of different magnesium alkoxides, catalysts, solvents as well as different aging times was investigated. XRD, MAS-NMR, FT-IR, thermal analysis and elemental analysis were applied to study the structure, composition and thermal behaviour of the bulk materials. The determination of the surface properties was accomplished with N2 and Ar adsorption–desorption isotherms.

• Structure and Properties of Noncrystalline Aluminum Oxide-Hydroxide Fluorides

  2010

  Chemistry of Materials · 46 Zitationen · DOI

  The thermal treatment of sol−gel derived aluminum hydroxide fluorides leads to new, X-ray amorphous, macroporous aluminum oxide-hydroxide fluorides. Followed by EA, DTA-TG, XPS, FT-IR, NH3-TPD, BET, XRD, and MAS NMR, it can be shown that the simplified composition of these compounds is “AlFO” and “AlF2O1/2”, respectively. These aluminum oxide-hydroxide fluorides exhibit a large number of acid centers. The local structure consists of AlFxOcn-x units (cn, coordination numbers 6, 5, 4), and all sites are partially fluorinated. It can be shown that bridged and terminal F-sites are related to 5- and 6-fold coordinated Al sites.

• Crystalline aluminium hydroxy fluorides—Suitable reference compounds for 19F chemical shift trend analysis of related amorphous solids

  2008

  Journal of Fluorine Chemistry · 46 Zitationen · DOI

• Nanocrystalline CaF2 particles obtained by high-energy ball milling

  2006

  Journal of Solid State Chemistry · 43 Zitationen · DOI

• Synthesis, structure determination, and formation of a theobromine : oxalic acid 2 : 1 cocrystal

  2014

  CrystEngComm · 42 Zitationen · DOI

  The structure and the formation pathway of a new theobromine : oxalic acid (2 : 1) cocrystal are presented.

• Local fluorine environments in nanoscopic magnesium hydr(oxide) fluorides studied by 19F MAS NMR

  2011

  Journal of Fluorine Chemistry · 41 Zitationen · DOI

• Catalytic Hydrodefluorination of Fluoromethanes at Room Temperature by Silylium‐ion‐like Surface Species

  2013

  Angewandte Chemie · 40 Zitationen · DOI

  Aluminiumchlorofluorid (ACF) katalysiert die Hydrodefluorierung sowie Friedel-Crafts-Reaktionen von fluorierten Methanen in der Gegenwart von Et3SiH. Eine oberflächengebundene Silyliumion-artige Spezies wird als das Schlüsselintermediat der C-F-Bindungsspaltung vermutet.

• High-energy ball milling—a possible synthesis route for cryolite and chiolite

  2006

  Solid State Sciences · 40 Zitationen · DOI

• Comparative structural investigation of aluminium fluoride solvates

  2006

  Solid State Sciences · 40 Zitationen · DOI

• Mechanochemical Synthesis, Characterization, and Structure Determination of New Alkaline Earth Metal-Tetrafluoroterephthalate Frameworks: Ca(<i>p</i>BDC-F₄)·4H₂O, Sr(<i>p</i>BDC-F₄)·4H₂O, and Ba(<i>p</i>BDC-F₄)

  2016

  Crystal Growth & Design · 39 Zitationen · DOI

  New fluorinated alkaline earth metal–organic frameworks were successfully synthesized by milling of metal hydroxides M(OH)2 with tetrafluoroterephthalic acid H2pBDC-F4. Both calcium- and strontium-tetrafluoroterephthalates are tetrahydrated, while the barium tetrafluoroterephthalate is free of coordinating water molecules. The two isomorphic structures Ca(pBDC-F4)·4H2O and Sr(pBDC-F4)·4H2O were solved from the powder diffraction data by ab initio structure determination and subsequent Rietveld refinement. The products were thoroughly characterized by elemental analysis, thermal analysis, magic-angle spinning NMR, Fourier transform infrared spectroscopy, scanning electron microscopy imaging, and Brunauer–Emmett–Teller measurements. Our findings suggest that the mechanochemical synthesis route is a promising approach for the preparation of new fluorinated alkaline earth metal–organic frameworks.

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Name

Dr. rer. nat. Gudrun Scholz

Titel

Dr. rer. nat.

Fakultät

Mathematisch-Naturwissenschaftliche Fakultät

Institut

Institut für Chemie

Telefon

+49 30 2093-7455

HU-FIS-Profil

Quelle ↗

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26.4.2026, 01:12:13