A5032643298- Lanthanide and Transition Metal Complexes
- Magnetism in coordination complexes
- Advanced NMR Techniques and Applications
- Radioactive element chemistry and processing
- Electron Spin Resonance Studies
- Advanced MRI Techniques and Applications
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- NMR spectroscopy and applications
- Metal complexes synthesis and properties
- Electrochemical Analysis and Applications
- Spectroscopy and Quantum Chemical Studies
- Inorganic and Organometallic Chemistry
- Chemical and Physical Properties in Aqueous Solutions
- Solid-state spectroscopy and crystallography
- Crystallography and molecular interactions
- MRI in cancer diagnosis
- Molecular spectroscopy and chirality
- Chemical Synthesis and Characterization
- Polyoxometalates: Synthesis and Applications
- Advanced Chemical Physics Studies
- Graphene research and applications
- Radiopharmaceutical Chemistry and Applications
- Nanoparticle-Based Drug Delivery
- Carbon Nanotubes in Composites
École Polytechnique Fédérale de Lausanne
2010-2019
University of Lausanne
1994-2015
Laboratoire de Chimie Moléculaire et Thioorganique
2011-2015
University of Minho
2015
École Polytechnique
2006-2013
Institut Lavoisier de Versailles
2009
Centre National de la Recherche Scientifique
2001-2009
Philips (United States)
2008
Laboratoire de Chimie
2004-2008
Charles Humbert 8
2006-2008
We study from first principles the magnetism in graphene induced by single carbon atom defects. For two types of defects considered our study, hydrogen chemisorption defect and vacancy defect, itinerant due to defect-induced extended states has been observed. Calculated magnetic moments are equal $1{\ensuremath{\mu}}_{B}$ per $1.12--1.53{\ensuremath{\mu}}_{B}$ depending on concentration. The coupling between is either ferromagnetic or antiferromagnetic, whether correspond same different...
We present the results of new and previously published 17O NMR, EPR, NMRD studies aqueous solutions Gd3+ octaaqua ion commercial MRI contrast agents [Gd(DTPA)(H2O)]2- (MAGNEVIST, Schering AG, DTPA = 1,1,4,7,7-pentakis(carboxymethyl)-1,4,7-triazaheptane), [Gd(DTPA-BMA)(H2O)] (OMNISCAN, Sanofi Nycomed, DTPA-BMA 1,7-bis[(N-methylcarbamoyl)methyl]-1,4,7-tris(carboxymethyl)-1,4,7-triazaheptane), [Gd(DOTA)(H2O)]- (DOTAREM, Guerbet, DOTA...
We report the nanoscale loading and confinement of aquated Gd3+n-ion clusters within ultra-short single-walled carbon nanotubes (US-tubes); these Gd3+n@US-tube species are linear superparamagnetic molecular magnets with Magnetic Resonance Imaging (MRI) efficacies 40 to 90 times larger than any Gd3+-based contrast agent (CA) in current clinical use.
We determined the structure of hydrated Cu(II) complex by both neutron diffraction and first-principles molecular dynamics. In contrast with generally accepted picture, which assumes an octahedrally solvated ion, our experimental theoretical results favor fivefold coordination. The simulation reveals that undergoes frequent transformations between square pyramidal trigonal bipyramidal configurations. argue this picture is also consistent data obtained previously visible near-infrared...
The water-soluble endohedral gadofullerene derivatives, Gd@C60(OH)x and Gd@C60[C(COOH)2]10, have been characterized with regard to their MRI contrast agent properties. Water-proton relaxivities measured in aqueous solution at variable temperature (278−335 K), for the first time gadofullerenes, as a function of magnetic field (5 × 10-4 9.4 T; NMRD profiles) are also reported. Both compounds show relaxivity maxima high fields (30−60 MHz) maximum 10.4 mM-1 s-1 Gd@C60[C(COOH)2]10 38.5 299 K....
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOxygen-17 NMR study of water exchange on gadolinium polyaminopolyacetates [Gd(DTPA)(H2O)]2- and [Gd(DOTA)(H2O)]- related to imagingKaroly Micskei, Lothar Helm, Erno Brucher, Andre E. MerbachCite this: Inorg. Chem. 1993, 32, 18, 3844–3850Publication Date (Print):September 1, 1993Publication History Published online1 May 2002Published inissue 1 September...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular Dynamics Simulation Study of Lanthanide Ions Ln3+ in Aqueous Solution Including Water Polarization. Change Coordination Number from 9 to 8 along the SeriesTh. Kowall, F. Foglia, L. Helm, and A. E. MerbachCite this: J. Am. Chem. Soc. 1995, 117, 13, 3790–3799Publication Date (Print):April 1, 1995Publication History Published online1 May 2002Published inissue 1 April...
Abstract Macrocyclic Gd III complexes attached to dendrimers represent a new class of potential MRI contrast agents. They have an extended lifetime in the blood pool, which is indispensable for their application magnetic resonance angiography, and high relaxivities, reduce dose required produce quality images. We performed variable‐temperature ‐pressure 17 O NMR study aqueous solution at 14.1, 9.4, 1.4 T on water exchange rotational dynamics three macrocyclic based polyamidoamine dendrimers,...
Water-dispersible gold nanoparticles functionalized with paramagnetic gadolinium have been fully characterized, and the NMRD profiles show very high relaxivities up to 1.5 T. Characterization using TEM images dynamic light scattering indicate a particle size distribution from 2 15 nm. The cores of do not contribute significantly overall magnetic moment.
Keywords: MRI contrast agnet gadolinium NMR relaxation Reference EPFL-CHAPTER-191350doi:10.1002/9781118503652.ch2 Record created on 2013-12-19, modified 2017-11-05
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOxygen-17 nuclear magnetic resonance kinetic study of water exchange on the lanthanide(III) aqua ionsCedric Cossy, Lothar Helm, and Andre E. MerbachCite this: Inorg. Chem. 1988, 27, 11, 1973–1979Publication Date (Print):June 1, 1988Publication History Published online1 May 2002Published inissue 1 June 1988https://pubs.acs.org/doi/10.1021/ic00284a028https://doi.org/10.1021/ic00284a028research-articleACS PublicationsRequest reuse permissionsArticle...
Abstract 17 O NMR longitudinal and tranverse relaxation rates chemical shifts were measured at variable temperature three magnetic fields (1.4, 4.7 9.4 T) for aqueous solutions of the complexes [Gd(H 2 O) 8 ] 3+ [Gd(PDTA)(H − . The transverse analysed in light recent EPR line width measurements to obtain parameters water exchange kinetics: k = (8.30 ± 0.95) × 10 (1.02 0.10) s −1 , Δ H ‡ 14.9 1.3 11.0 1.4 kJ mol S −24.1 4.1 −54.6 4.6 J K respectively. used rotation time complexes: τ (2.9 0.2)...
For the first time, a very general theoretical method is proposed to interpret full electron paramagnetic resonance (EPR) spectra at multiple temperatures and frequencies in important case of S-state metal ions complexed liquid solution. This illustrated by careful analysis measured two Gd3+ (S = 7/2) complexes. It shown that electronic relaxation mechanisms origin EPR line shape arise from combined effects modulation static crystal field random Brownian rotation complex transient zero-field...
Fast water exchange rate constants on diamagnetic metal ions can be measured using either a paramagnetic chemical shift agent or relaxation agent. An approximate analytical equation was developed for the method, valid in limit of rapid exchange. The limits validity these methods are discussed. These were applied to study [Mg(H2O)]62+ over large temperature range (252–350 K) and up pressure 200 MPa by 17O NMR, leading following kinetic parameters: kMg298=6.7±0.2×105 s-1; ΔHMg‡=49.1±0.7 kJ...
The dynamics of water molecules in Cu2+ aqueous solutions were investigated by 17O NMR at several temperatures and magnetic fields. A theory is developed for scalar relaxation the presence Jahn–Teller inversion aquaion exchange between bulk, a model where much faster than coupling negligible axially bound molecules. It shown that this consistent with experimental results, while standard expressions, ignoring influence inversion, are clearly inconsistent observed longitudinal rates. process...
With their nanoscalar, superparamagnetic Gd3+-ion clusters (1 × 5 nm) confined within ultrashort (20−80 single-walled carbon nanotube capsules, gadonanotubes are high-performance T1-weighted contrast agents for magnetic resonance imaging (MRI). At 1.5 T, 37 °C, and pH 6.5, the r1 relaxivity (ca. 180 mM-1 s-1 per Gd3+ ion) of is 40 times greater than any current ion-based clinical agent. Herein, we report that also ultrasensitive pH-smart probes with r1/pH response from 7.0−7.4 being an order...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHigh-pressure NMR kinetics. Part 34. Variable-temperature and variable-pressure kinetic study of solvent exchange on hexaaquaruthenium(3+) -(2+) hexakis(acetonitrile)ruthenium(2+)Irina Rapaport, Lothar Helm, Andre E. Merbach, Paul Bernhard, Andreas LudiCite this: Inorg. Chem. 1988, 27, 5, 873–879Publication Date (Print):March 1, 1988Publication History Published online1 May 2002Published inissue 1 March...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHigh-pressure NMR study. 38. Water-exchange mechanisms on the terbium to thulium octaaqualanthanide(III) ions: a variable-pressure oxygen-17 studyCedric Cossy, Lothar Helm, and Andre E. MerbachCite this: Inorg. Chem. 1989, 28, 14, 2699–2703Publication Date (Print):July 1, 1989Publication History Published online1 May 2002Published inissue 1 July 1989https://pubs.acs.org/doi/10.1021/ic00313a003https://doi.org/10.1021/ic00313a003research-articleACS...