Publications by Lothar Helm | EPFL Graph Search

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A multiple-frequency (9.4-325 GHz) and variable-temperature (276-320 K) electron paramagnetic resonance (EPR) study on low molecular weight gadolinium(III) complexes for potential use as magnetic resonance imaging (MRI) contrast agents has been performed. ...

Rotational correlation times of metal ion aqua complexes can be detd. from 17O NMR relaxation rates if the quadrupole coupling const. of the bound water oxygen-17 nucleus is known. The rotational correlation time is an important parameter for the efficienc ...

We study from first principles the magnetism in graphene induced by single carbon atom defects. For two types of defects considered in our study, the hydrogen chemisorption defect and the vacancy defect, the itinerant magnetism due to the defect-induced ex ...

Tellurium is the only element which forms a variety of minerals with gold as principal component (e.g. calaverite AuTe2, krennerite (AuAg)Te2, petzite Ag3AuTe2 and sylvanite AgAuTe4). These minerals have been known for a long time and are of economic value ...

A simple scheme for the evaluation of the core spin-polarization contribution within pseudopotential electronic structure methods is proposed. The method uses a reconstruction of the all-electron wave functions and the frozen valence spin-d. approxn. to so ...

Homoleptic acetonitrile complexes [Nd(CH3CN)(9)]Al(OC(CF3)(3))(4), [Dy(CH3CN)(9)]Al(OC(CF3)(3))(4), and [Tm(CH3CN)(8)]Al(OC(CF3)(3))(4) have been studied in anhydrous acetonitrile by 14N and 1H NMR relaxation. Solvent-exchange rate constants ...

Gd(III) (S = 7/2) polyaminocarboxylates, used as contrast agents for Magnetic Resonance Imaging (MRI), were studied in frozen solutions by High-Frequency-High-Field Electron Paramagnetic Resonance (HF-EPR). EPR spectra recorded at 240 GHz and temperatures ...

A synthetic nano building block endowed with amphiphilic properties and chelated gadoliniumis presented. Spontaneous self-assembly into small 12 nm corona-core stealth Gd-micelles with inherently high gadolinium loading occurs in water. Gd-Micelles are a n ...

Dimeric peptidic vectors, obtained by the divalent grafting of bombesin analogues on a newly synthesized DOTA-based prochelator, showed improved qualities as tumor targeted imaging probes in comparison to their monomeric analogues. ...

The labile cobalt (II) complex [Co(TUF)2(Pic)2] with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione (TUF) bidentate and 4-methylpyridine (Pic) monodentate ligands was studied by variable temp. (VT) 19F NMR from 184 to 312 K. In contrast to the solid state, ...

The pH-dependent water-exchange rates of [(CO)2(NO)Re(H2Ocis)2(H2Otrans)]2+ (1) in aq. media were investigated by means of 17O NMR spectroscopy at 298 K. Because of the low pKa value found for 1 (pKa = 1.4 ± 0.3), the water-exchange rate const. kobsH2Otran ...

Lothar Helm

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Design of Gd(III)-Based Magnetic Resonance Imaging Contrast Agents: Static and Transient Zero-Field Splitting Contributions to the Electronic Relaxation and Their Impact on Relaxivity

17O nuclear quadrupole coupling constants of water bound to a metal ion: A gadolinium(III) case study

Defect-induced magnetism in graphene

Tellurium speciation under hydrothermal conditions

Aqueous solubility and speciation of Te(IV) at elevated temperatures

Core spin-polarization correction in pseudopotential-based electronic structure calculations

Quantum Chemical Investigation of Hyperfine Coupling Constants on First Coordination Sphere Water Molecule of Gadolinium(III) Aqua Complexes

Relevance of the Ligand Exchange Rate and Mechanism of fac-[(CO)3M(H2O)3]+ (M = Mn, Tc, Re) Complexes for New Radiopharmaceuticals

Solvent Exchange and Electron-Spin Relaxation on Homoleptic Acetonitrile Complexes of Trivalent Lanthanides

Spectroscopic investigation of Tellurium in chloride brines

A High-Frequency EPR Study of Frozen Solutions of Gd(III) Complexes: Straightforward Determination of the Zero-Field Splitting Parameters and Simulation of the NMRD Profiles

MRI micelles self-assembled from synthetic gadolinium-based nano building blocks

High relaxivity MRI contrast agents for high magnetic field - challenges and pitfalls

Gadolinium(III) complexes of mono-and diethyl esters of monophosphinic acid analogue of DOTA as potential MRI contrast agents: solution structures and relaxometric studies

Physicochemical and MRI characterization of Gd3+-loaded polyamidoamine and hyperbranched dendrimers

Rigid M(II)L2Gd(III)2 (M=Fe, Ru) Complexes of a Terpyridine-Based Heteroditopic Chelate: A Class of Candidates for MRI Contrast Agents

Novel DOTA-based prochelator for divalent peptide vectorization: synthesis of dimeric bombesin analogues for multimodality tumor imaging and therapy

Isomerization mechanisms of a labile Co(II) octahedral complex

Water-Exchange Study Revealed Unexpected Substitution Behavior of [(CO)2(NO)Re(H2O)3]2+ in Aqueous Media

Inorganic and Bioinorganic Solvent Exchange Mechanisms