A5001770735- Magnetism in coordination complexes
- Iron oxide chemistry and applications
- Metalloenzymes and iron-sulfur proteins
- Iron Metabolism and Disorders
- Metal-Catalyzed Oxygenation Mechanisms
- Metal complexes synthesis and properties
- X-ray Diffraction in Crystallography
- Magnetic Properties and Synthesis of Ferrites
- Crystallization and Solubility Studies
- Magnetic properties of thin films
- Trace Elements in Health
- Characterization and Applications of Magnetic Nanoparticles
- Geomagnetism and Paleomagnetism Studies
- Nanocluster Synthesis and Applications
- Inorganic Chemistry and Materials
- Multiferroics and related materials
- Iron-based superconductors research
- Advanced Condensed Matter Physics
- Hemoglobin structure and function
- Quantum Dots Synthesis And Properties
- Inorganic Fluorides and Related Compounds
- Electrochemical Analysis and Applications
- Lanthanide and Transition Metal Complexes
- Hemoglobinopathies and Related Disorders
- Ferrocene Chemistry and Applications
Villanova University
2013-2025
National Centre of Scientific Research "Demokritos"
2007-2020
Centro Brasileiro de Pesquisas Físicas
2015
Institute of Bioengineering and Nanotechnology
2005-2009
Brookhaven National Laboratory
2007
State University of New York
2007
Center for Nanoscale Science and Technology
2005
University of Maryland, College Park
2005
Columbia University
1974-2004
Brown University
2002
As-prepared, single-crystalline bismuth ferrite nanoparticles show strong size-dependent magnetic properties that correlate with: (a) increased suppression of the known spiral spin structure (period length ∼62 nm) with decreasing nanoparticle size and (b) uncompensated spins strain anisotropies at surface. Zero-field-cooled field-cooled magnetization curves exhibit spin-glass freezing behavior due to a complex interplay between finite effects, interparticle interactions, random distribution...
Quantum dots (QDs) and magnetic nanoparticles (MPs) are of interest for biological imaging, drug targeting, bioconjugation because their unique optoelectronic properties, respectively. To provide water solubility biocompatibility, QDs MPs were encapsulated within a silica shell using reverse microemulsion synthesis. The resulting SiO2/MP−QD nanocomposite particles present combination optical properties. Their nonporous allows them to be surface modified in various biomedical applications.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT[Fe(OMe)2(O2CCH2Cl)]10, a Molecular Ferric WheelKingsley L. Taft, Christopher D. Delfs, Georgia C. Papaefthymiou, Simon Foner, Dante Gatteschi, and Stephen J. LippardCite this: Am. Chem. Soc. 1994, 116, 3, 823–832Publication Date (Print):February 1, 1994Publication History Published online1 May 2002Published inissue 1 February 1994https://pubs.acs.org/doi/10.1021/ja00082a001https://doi.org/10.1021/ja00082a001research-articleACS PublicationsRequest...
We have investigated the structural, magnetic, and electronic properties of nonstoichiometric iron oxide nanocrystals prepared by decomposition iron(II) iron(0) precursors in presence organic solvents capping groups. The highly uniform, crystalline, monodisperse that were produced enabled a full structural compositional survey electron microscopy X-ray diffraction. complex metastable behavior (wüstite) at nanoscale was studied combination Mossbauer spectroscopy magnetic characterization....
Reverse microemulsion techniques combined with templating strategies have led to the synthesis of four types nanoparticles. First, homogeneous SiO2-coated Fe2O3 (SiO2/Fe2O3) nanoparticles controlled SiO2 shell thickness (1.8−30 nm) were synthesized by reverse microemulsion. These nanocomposite particles used as templates for deposition a mesoporous silica shell. The iron oxide core in SiO2/Fe2O3 could be partially and completely etched produce rattle-type nanoballs hollow nanoballs,...
Graphene oxide (GO) offers interesting physicochemical and biological properties for biomedicine due to its versatility, biocompatibility, small size, large surface area, ability interact with cells tissues. GO is a two-dimensional material of exceptional strength, unique optical, physical, mechanical, electronic properties. Ease functionalization high antibacterial activity are two major identified GO. Due excellent aqueous processability, amphiphilicity, capability, enhanced Raman...
Fe3O4–Ag heterodimer nanocomposites of tunable sizes are synthesized with high yield under mild conditions, without the loss magnetic moment. A ligand-exchange scheme is devised utilizing bifunctionality system to render nanocomposite soluble in aqueous solutions. Cells labeled nanoparticles can be magnetically manipulated and imaged two-photon fluorescence microscopy. Detailed facts importance specialist readers published as "Supporting Information". Such documents peer-reviewed, but not...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAssembly and characterization of an accurate model for the diiron center in hemerythrinWilliam H. Armstrong, Alan Spool, Georgia C. Papaefthymiou, Richard B. Frankel, Stephen J. LippardCite this: Am. Chem. Soc. 1984, 106, 12, 3653–3667Publication Date (Print):June 1, 1984Publication History Published online1 May 2002Published inissue 1 June 1984https://pubs.acs.org/doi/10.1021/ja00324a041https://doi.org/10.1021/ja00324a041research-articleACS...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTX-ray absorption, Moessbauer, and EPR studies of the dinuclear iron center in hydroxylase component methane monooxygenaseJane G. DeWitt, James Bentsen, Amy C. Rosenzweig, Britt Hedman, Jeffrey Green, Simon Pilkington, Georgia Papaefthymiou, Howard Dalton, Keith O. Hodgson, Stephen J. LippardCite this: Am. Chem. Soc. 1991, 113, 24, 9219–9235Publication Date (Print):November 1, 1991Publication History Published online1 May 2002Published inissue 1...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAxial ligation modes in iron(III) porphyrins. Models for the oxidized reaction states of cytochrome P-450 enzymes and molecular structure protoporphyrin IX dimethyl ester p-nitrobenzenethiolateS. C. Tang, S. Koch, G. Papaefthymiou, Foner, R. B. Frankel, James A. Ibers, H. HolmCite this: J. Am. Chem. Soc. 1976, 98, 9, 2414–2434Publication Date (Print):April 1, 1976Publication History Published online1 May 2002Published inissue 1 April...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and characterization of (.mu.-hydroxo)bis(.mu.-acetato)diiron(II) (.mu.-oxo)bis(.mu.-acetato)diiron(III) 1,4,7-trimethyl-1,4,7-triazacyclononane complexes as models for binuclear iron centers in biology; properties the mixed valence diiron(II,III) speciesJudith Ann R. Hartman, Lynn Rardin, Phalguni Chaudhuri, Klaus Pohl, Karl Wieghardt, Bernhard Nuber, Johannes Weiss, Georgia C. Papaefthymiou, Richard B. Frankel, Stephen J. LippardCite...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthetic analogs of the active sites iron-sulfur proteins. 14. Synthesis, properties, and structures bis(o-xylyl-.alpha.,.alpha.'-dithiolato)ferrate(II,III) anions, oxidized reduced rubredoxin sitesR. W. Lane, James A. Ibers, R. B. Frankel, G. C. Papaefthymiou, H. HolmCite this: J. Am. Chem. Soc. 1977, 99, 1, 84–98Publication Date (Print):January 1977Publication History Published online1 May 2002Published inissue 1 January...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis, structure, and properties of an undecairon(III) oxo-hydroxo aggregate: approach to the polyiron core in ferritinSergiu M. Gorun, Georgia C. Papaefthymiou, Richard B. Frankel, Stephen J. LippardCite this: Am. Chem. Soc. 1987, 109, 11, 3337–3348Publication Date (Print):May 1, 1987Publication History Published online1 May 2002Published inissue 1...
Mammalian ferritin from horse spleen undergoes an electrochemical or chemical reduction reaction in which each iron atom present is reduced by one electron (2300 electrons per molecule containing 2300 Fe3+ ions). Midpoint potentials of -190 mV, -310 and -416 mV were determined at pH 7.0, 8.0, 9.0. This variation potential with indicates that approximately 2 H+ are transferred to the core for Fe2+. Mössbauer measurements partially give spectra consist a ferric quadrupole doublet superposed...
A novel polyiron oxo complex, [Fe III 4 Fe II 8 (O) 2 (OCH 3 ) 18 (O CCH 6 (CH OH) 4.67 ] (1), has been prepared from ferrous acetate and lithium methoxide in methanol by slow addition of dioxygen. The three-dimensional close-packed layered structure found 1 closely mimics that proposed for the inorganic core iron storage protein ferritin. Mössbauer spectra reveal superparamagnetic relaxation at temperatures below 15 K, a property characteristic ferritin core. small size mixed-valent nature...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGround spin state variability in [Fe4S4(SR)4]3-. Synthetic analogs of the reduced clusters ferredoxins and other iron-sulfur proteins: cases extreme sensitivity electronic structure to extrinsic factorsM. J. Carney, G. C. Papaefthymiou, K. Spartalian, R. B. Frankel, Richard H. HolmCite this: Am. Chem. Soc. 1988, 110, 18, 6084–6095Publication Date (Print):August 1, 1988Publication History Published online1 May 2002Published inissue 1 August...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthetic analogs of the 4-Fe active sites reduced ferredoxins. Electronic properties tetranuclear trianions [Fe4S4(SR)4]3- and structure [(C2H5)3(CH3)N]3[Fe4S4(SC6H5)4]E. J. Laskowski, R. B. Frankel, W. O. Gillum, G. C. Papaefthymiou, Renaud, James A. Ibers, H. HolmCite this: Am. Chem. Soc. 1978, 100, 17, 5322–5337Publication Date (Print):August 1, 1978Publication History Published online1 May 2002Published inissue 1 August...
We report on the M\"ossbauer spectra and magnetization properties of single-crystalline ${({\text{BiFeO}}_{3})}_{x}\text{\ensuremath{-}}{({\text{BaTiO}}_{3})}_{1\ensuremath{-}x}$ solid solution nanostructures in form nanocubes, measuring approximately 150 to 200 nm a side, prepared by molten salt solid-state reaction method compositional range wherein $0.5\ensuremath{\le}x\ensuremath{\le}1$. Powder x-ray diffraction (XRD) monochromatic synchrotron XRD studies indicate products high purity,...
The magnetic spinel ferrites, MFe2O4 (wherein "M" = a divalent metal ion such as but not limited to Mn, Co, Zn, and Ni), represent unique class of materials in which the rational introduction different "M"s can yield correspondingly interesting behaviors. Herein we present generalized hydrothermal method for synthesis single-crystalline ferrite nanoparticles with M Mg, Fe, Ni, Cu, respectively, be systematically efficaciously produced simply by changing precursor. Our protocol moreover lead...
The development of self-assembled magnetic CoFe2O4 nanoparticles within polymer matrices at room temperature is reported. Diblock copolymers consisting poly (norbornene) and (norbornene-dicarboxcylic acid) (NOR/NORCOOH) were synthesized. self-assembly the mixed metal oxide NORCOOH block was achieved by processing copolymer nanocomposite using wet chemical methods. Morphology properties determined superconducting quantum interference device magnetometry, transmission electron microscopy, wide...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIron and manganese alkoxide cubesKingsley L. Taft, Andrea Caneschi, Laura E. Pence, Christopher D. Delfs, Georgia C. Papaefthymiou, Stephen J. LippardCite this: Am. Chem. Soc. 1993, 115, 25, 11753–11766Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Published inissue 1 December 1993https://pubs.acs.org/doi/10.1021/ja00078a014https://doi.org/10.1021/ja00078a014research-articleACS PublicationsRequest reuse...
Iron oxide nanoclusters were synthesized within mesoporous MCM-41 aluminosilicate matrices via evaporation-condensation of volatile Fe(CO)5. The well-defined hexagonally packed cylindrical pore structure led to the derivation γ-Fe2O3 particles with spherical and elongated morphologies. Magnetization studies Mössbauer spectroscopy indicated that γ-Fe2O3/MCM-41 nanocomposites exhibited interesting superparamagnetic behavior. A blue shift in absorption edge relative bulk iron was noted UV−Vis...