Publications by André Merbach

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Magnetic resonance imaging is one of the most efficient diagnostic modalities in clinical radiology and biomedical research. To enhance image contrast, paramagnetic complexes, mainly Gd3+ chelates, are used. Today, around one third of all medical MR images are generated with the use of a contrast medium and this number is expected to increase with the development of new applications and new agents. Recently, molecular imaging has emerged as a new area aiming at non-invasive visualisation of expression and f

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 ...

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] ...

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 ...

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 ...

The time correlation functions of the electronic spin components of a metal ion without orbital degeneracy in solution are computed. The approach is based on the numerical solution of the time-dependent Schrödinger equation for a stochastic perturbing Hamiltonian which is simulated by a Monte Carlo algorithm using discrete time steps. The perturbing Hamiltonian is quite general, including the superposition of both the static mean crystal field contribution in the molecular frame and the usual transient liga

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 ...

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 ...

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 ...

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 ...

For the low-spin t2g6 Ru(OH2)62+ (ΔV⧧ = −0.4 cm3 mol-1) and Rh(OH2)63+ (ΔV⧧ = −4.2 cm3 mol-1) hexaaquaions, the respective Id and Ia water exchange mechanisms had been assigned, mainly on the basis of activation volumes ΔV⧧ and entering ligands effects for water substitution. For Ru(II) the near-zero ΔV⧧ was supposed to be due to the compensation between a positive contribution (the loss of a water molecule) and a negative one (the contraction of the bonds of the five spectator ligands at the transition sta

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 ...

For the first time, a very general theoretical method is proposed to interpret the full electron paramagnetic resonance (EPR) spectra at multiple temperatures and frequencies in the important case of S-state metal ions complexed in liquid solution. This method is illustrated by a careful analysis of the measured spectra of two Gd3+ (S = 7/2) complexes. It is shown that the electronic relaxation mechanisms at the origin of the EPR line shape arise from the combined effects of the modulation of the static cry

The stability and water exchange dynamics of gadolinium (GdIII) complexes are critical characteristics that determine their effectiveness as contrast agents for magnetic resonance imaging (MRI). A new heteropodal GdIII chelate, [Gd-TREN-bis(6-Me-HOPO)-(TAM-TRI)(H2O)2] (Gd-2), is presented which is based on a hydroxypyridinate (HOPO)-terephthalamide (TAM) ligand design. Thermodynamic equilibrium constants for the acid−base properties and the GdIII complexation strength of TREN-bis(6-Me-HOPO)-(TAM-TRI) (2) we

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 ...

Classical molecular dynamics simulations with a force field adapted to the family of Gd3+ polyaminocarboxylate complexes have been successfully applied on two macrocyclic ([Gd(DOTA)(H2O)]- and [Gd(DO3A)(H2O)2]) and two acyclic ([Gd(DTPA)(H2O)]2- and [Gd(EGTA)(H2O)]-) complexes in aqueous solution (DOTA=1,4,7,10-tetrakis(carboxymethyl)-1,4,7,10-tetraazacyclododecane, DO3A=1,4,6-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane, DTPA=1,1,4,7,7-pentakis(carboxymethyl)-1,4,7-triazaheptane, EGTA=1,1,10,10-tetra

The C2-sym. electron-poor ligand (R)-BINOP-F (4; (R)-2,2'-[bis(pentafluorophenyl)phosphinoxy]-1,1'-binaphthalene) was prepd. by reaction of (R)-BINOL ((R)-1,1'-binaphthalene-2,2'-diol) with bromobis(pentafluorophenyl)phosphine in the presence of NEt3. The iodo complex [CpRu((R)-BINOP-F)(I)] ((R)-6) was obtained by substitution of two carbonyl ligands by (R)-4 in the in situ-prepd. [CpRu(CO)2H] complex followed by reaction with iodoform. Complex 6 was reacted with [Ag(SbF6)] in acetone to yield [CpRu((R)-BIN

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- ...

The invention relates to a novel class of ligands, complexes comprising such ligands and a metal ion, and adducts of these metal complexes and a macromolecule. Pharmaceutical compositions and methods of making and using the ligand-metal complexes are also described. The invention also relates to the use of macromolecular adducts for enhancement of diagnostic imaging. In particular, the invention relates to (ethylene)-(propylene)-triaminepentaacetic acid (EPTPA) derivatives, a process for their production, a

Taking advantage of the Curie contribution to the relaxation of the protons in the Tb(III) complex, and the quadrupolar relaxation of the 17O and 2H nuclei on the Eu(III) complex, the effect of the internal motion of the water molecule bound to [Ln(DOTAM)(H2O)]3+ complexes was quantified. The determination of the quadrupolar coupling constant of the bound water oxygen X_O(1 + eta_O^2/3)1/2 = 5.2 ± 0.5 MHz allows a new analysis of the 17O and 1H NMR data of the [Gd(DOTA)(H2O)]- complex with different rotatio

André Merbach

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Metal Complexes as MRI Contrast Enhancement Agents

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

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

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

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

A general approach to the electronic spin relaxation of Gd(III) complexes in solutions. Monte Carlo simulations beyond the Redfield limit

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

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

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

The Periodic Table and Kinetics?

Can Octahedral t2g6 Complexes Substitute Associatively? The Case of the Isoelectronic Ruthenium(II) and Rhodium(III) Hexaaquaions

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

EPR Spectroscopy of MRI-Related Gd(III) Complexes: Simultaneous Analysis of Multiple Frequency and Temperature Spectra, Including Static and Transient Crystal Field Effects

A Highly Stable Gadolinium Complex with a Fast, Associative Mechanism of Water Exchange

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

MD simulations of acyclic and macrocyclic Gd3+-based MRI contrast agents: Influence of the internal mobility on water proton relaxivity

[CpRu((R)-Binop-F)(H2O)][SbF6], a New Fluxional Chiral Lewis Acid Catalyst: Synthesis, Dynamic NMR, Asymmetric Catalysis, and Theoretical Studies

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

Preparation of (ethylene)-(propylene)-triaminepentaacetic acid derivatives for use in the production of pharmaceutical agents

How Does Internal Motion Influence the Relaxation of the Water Protons in LnIIIDOTA-like Complexes?