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André Merbach

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Publications associées (40)

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Lanthanide Complexes Formed with the Tri- and Tetraacetate Derivatives of Bis(aminomethyl)phosphinic Acid: Equilibrium, Kinetic and NMR Spectroscopic Studies

André Merbach, Laurent Quebatte

The lanthanide(III) complexes formed with the tri- and tetraacetate derivatives of bis(aminomethyl)phosphinic acid, L1 and L2, respectively, have been studied by pH potentiometry, spectrophotometry and 1H and 17O NMR spectroscopy. L1 forms [Ln(L1)], [Ln(L1 ...

Wiley-Blackwell2012

Isomerization Mechanisms of Stereolabile tris- and bis-Bidentate Octahedral Cobalt(II) Complexes: X-ray Structure and Variable Temperature and Pressure NMR Kinetic Investigation

Rosario Scopelliti, André Merbach, Lothar Helm, Fabrice Riblet

The isomerization dynamics of five labile octahedral Co(II) compounds have been investigated by variable temperature and pressure 1H and 19F NMR spectroscopy in dichloromethane solution. The X-ray crystal structure of the two tris-chelates, [Co(HFA)2bpic] ...

American Chemical Society2010

NMR Study of Ligand Exchange and Electron Self-Exchange between Oxo-Centered Trinuclear Clusters [Fe3(μ3-O)(μ-O2CR)6(4-R´py)3]+/0

André Merbach, Lothar Helm

The syntheses, single crystal X-ray structures, and magnetic properties of the homometallic mu(3)-oxo trinuclear clusters Fe-3(mu(3)-O)(mu-O2CCH3)(6)(4-Phpy)(3) (1) and F(e)3(mu(3)-O)(mu-O(2)CAd)(6)(4-Mepy)(3) (2) are reported (Ad = adamanta ...

American Chemical Society2011

In vivo MRI assessment of a novel GdIII-based contrast agent designed for high magnetic field applications

André Merbach, Lothar Helm, Joao Bruno Livramento Fig.

Gd3L is a trinuclear Gd3R complex of intermediate size, designed for contrast agent applications in high field magnetic resonance imaging (H12L is based on a trimethylbenzene core bearing three methylene-diethylenetriamine-N,N,N00,N00-tetraacetate moieties ...

2008

Kinetic studies on the first dihydrogen aquacomplex, [Ru(H2)(H2O)5]2+: Formation under H2 pressure and catalytic H/D isotope exchange in water

André Merbach, Lothar Helm, Gabor Laurenczy, Oleg Yazyev, Pascal Grundler

The ruthenium(II) hexaaqua complex [Ru(H2O)6]2+ reacts with dihydrogen under pressure to give the h2-dihydrogen ruthenium(II) pentaaqua complex [Ru(H2)(H2O)5]2+.The complex was characterized by 1H, 2H and 17O NMR: d H = -7.65 ppm, J HD = 31.2 Hz, d O = -80 ...

2006

The effect of pyridinecarboxylate chelating groups on the stability and electronic relaxation of gadolinium complexes

André Merbach, Lothar Helm, Marinella Mazzanti, Alain Borel

The ligand N,N'-bis[6-carboxy-2-pyridylmethyl]ethylenediamine-N,N'-diacetic acid (H4bpeda) was synthesized using an improved procedure which requires a reduced no. of steps and leads to a higher yield with respect to the published procedure. It was obtaine ...

2005

Phosphinic derivative of DTPA conjugated to a G5 PAMAM dendrimer: an 17O and 1H relaxation study of its Gd(III) complex

André Merbach, Lothar Helm

A DTPA-based chelate containing one phosphinate group was conjugated to a generation 5 polyamidoamine (PAMAM) dendrimer via a benzylthiourea linkage. The Gd(III) complex of this novel conjugate has potential as a contrast agent for magnetic resonance imagi ...

2006

The Periodic Table and Kinetics?

André Merbach, Lothar Helm

Mendeleev in his first publication ordered the chemical elements following an apparent periodicity of properties such as atomic volume and valence. The reactivity of the elements was only studied systematically many years later. To illustrate the systemati ...

2019

A Starburst-Shaped Heterometallic Compound Incorporating Six Densely Packed Gd3+ Ions

André Merbach, Alain Borel, Joao Bruno Livramento Fig.

The heterotritopic ligand [bpy(DTTA)2]8- has two diethylenediamine-tetraacetate units for selective lanthanide(III) coordination and one bipyridine function for selective FeII coordination. In aqueous solution and in the presence of these metals, the ligan ...

2006

A benzene-core trinuclear GdIII complex: towards the optimization of relaxivity for MRI contrast agent applications at high magnetic field

André Merbach, Lothar Helm, Joao Bruno Livramento Fig.

A novel ligand, H12L, based on a trimethylbenzene core bearing three methylenediethylenetriamine-N,N,N,N- tetraacetate moieties (–CH2DTTA4–) for Gd3+ chelation has been synthesized, and its trinuclear Gd3+ complex [Gd3L(H2O) 6]3– investigated with respect ...

2008

A PCP-Pincer RuII-Terpyridine Building Block as a Potential "Antenna Unit" for Intramolecular Sensitization

André Merbach

The redox- and photoactive mononuclear complex [Ru(PCP)(tpy-DTTANa4)]Cl {PCP = [C6H3(CH2PPh2)2-2,6]-; tpy-DTTA4- = 4'-(2,2':6',2''-terpyridine)-diethylenetriamine-N,N,N'',N''-tetraacetate} possesses an externally directed, vacant N3O4 polyaminocarboxylate- ...

2007

Mechanism of Pyridine-Ligand Exchanges at the Different Labile Sites of 3d Heterometallic and Mixed Valence μ3-oxo Trinuclear Clusters

Rosario Scopelliti, André Merbach, Lothar Helm, Fabrice Riblet

The syntheses and single crystal X-ray structural analysis of five novel hetero- and homometallic μ3-oxo trinuclear cluster with the formula [FeIII2MII(μ3-O)(μ-O2CCH3)6(4-Rpy)3] · x(4-Rpy) · y(CH3CN) where R ) Ph for 1(Fe2Mn),2(Fe2Fe), 3(Fe2Co), 4(Fe2Ni) a ...

2008

Positively Charged GdIII Cryptates: Slow, Associative Water Exchange

André Merbach, Lothar Helm

A combined variable-temp. and multiple field 17O NMR, EPR and NMRD study was performed for the 1st time on Gd(III) complexes of cryptand ligands, L1 and L2, where L1 contains three 2,2'-bipyridine units ([bpy.bpy.bpy]) and L2 is the disubstituted Me ester ...

2006

Multiple Frequency and Variable Temperature EPR study of Gd(III) polyaminocarboxylates: analysis and comparison of the magnetically dilute powder and the frozen solution spectra

André Merbach, Lothar Helm, Alain Borel

An Electron Paramagnetic Resonance (EPR) study of glasses and magnetically dilute powders of [Gd(DTPA)(H2O)]2−, [Gd(DOTA)(H2O)]-, and macromolecular Gd-P792 complexes was carried out at X-, Q-band and 240 GHz DTPA=diethylenetriaminepentaacetato; DOTA=1,4,7 ...

Wiley-VHCA AG2009

First in vivo MRI assessment of a self-assembled metallostar compound endowed with a remarkable high field relaxivity

André Merbach, Lothar Helm, Joao Bruno Livramento Fig.

{Fe[Gd2bpy(DTTA)2(H2O)4]3}4- is a self-assembled, metallostar-structured potential MRI contrast agent, with six efficiently relaxing Gd3+ centers confined into a small mol. space. Its proton relaxivity is particularly remarkable at very high magnetic field ...

2006

Water-Soluble Gadofullerenes: Toward High-Relaxivity, pH-Responsive MRI Contrast Agents

André Merbach, Lothar Helm, Alain Borel

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 have been measured in aqueous solution at variable temperature ...

2005

Rotational Dynamics Account for pH-Dependent Relaxivities of PAMAM Dendrimeric, Gd-Based Potential MRI Contrast Agents

André Merbach, Sabrina Laus

The EPTPA5- chelate, which ensures fast water exchange in GdIII complexes, has been coupled to three different generations (5, 7, and 9) of polyamidoamine (PAMAM) dendrimers through benzylthiourea linkages (H5EPTPA=ethylenepropylenetriamine-N,N,N,N,N-penta ...

2005

Reactivity of the novel organometallic aqua-ion [(CO)2(NO)Re(H2O) 3]2+: Kinetics of H2O substitution and 17O exchange of CO ligands

André Merbach, Pascal Grundler, Marie-Line Lehaire

2005

Supramolecular Assembly of an Amphiphilic GdIII Chelate: Tuning the Reorientational Correlation Time and the Water Exchange Rate

André Merbach

2006

Gadonanotubes as Ultrasensitive pH-Smart Probes for Magnetic Resonance Imaging

André Merbach, Lothar Helm, Sabrina Laus

With their nanoscalar, superparamagnetic Gd3+-ion clusters (1 ´ 5 nm) confined within ultrashort (20-80 nm) single- walled carbon nanotube capsules, gadonanotubes are high- performance T1-weighted contrast agents for magnetic resonance imaging (MRI). At 1. ...

American Chemical Society (ACS)2008