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Gd(III) (S =7/2) polyaminocarboxylates, used as contrast agents for Magnetic Resonance Imaging were studied in frozen solutions by High-Frequency-High Field Electron Paramagnetic Resonance (HF-EPR). The EPR spectra recorded at 240 GHz and temperatures below 150 K allowed the direct and straightforward determination of parameters governing the strength of zero-field splitting (ZFS).

The water-soluble endohedral gadofullerene derivatives are characterized with regard to their magnetic resonance imaging (MRI) contrast agent properties. The pH dependency of the proton relaxivities makes these gadofullerene derivatives prime candidates for pH-responsive magnetic resonance imaging contrast agent applications.

The first variable-temperature and variable-pressure stopped-flow spectrophotometric study of the sequential threading of alpha-cyclodextrin (alpha-CD) onto the guest dye Mordant Orange 10, S, is described. The quantitative ground-state and activation enthalpy, entropy and volume change studies indicate that hydrational, van der Waals, and conformational changes in S and alpha-CD determine the equilibrium and kinetic character of the system.

MRI-related Gd(III) complexes were studied using EPR spectroscopy.

Research is presented concerning the use of controlled potential coulometry to prepare a (EuII(diethylenetriamine pentaacetate)(H20))3- complex from (EuIII(diethylenetriamine pentaacetate))2-.

(Eu(DOTAM)(H20)(super3+)) was studied to determine the mechanism of the water exchange from variable temperature and pressure (super1)H and (super17) 0 NMR data.

Research is presented describing the use of NMR to measure variable-pressure (9.4 T) and variable-temperature (at 4.7 and 9.4 T) 17O nuclear relaxation rates for the Eu(II) aqua ion. The implications for magnetic resonance imaging contrast agents and ligand exchange at Ca(II) are discussed.

The lability of mononuclear octahedral complex as compared to the dinuclear triple-helical complex of cobalt has been investigated. Electrospray mass spectroscopy (ESMS) was utilized to study the ligand exchange in the triple-helical complex and establishes the formation pathway of this complex. The slow racemization of the dinuclear triple complex is due to the slow dissociative mechanism of cobalt from the complex. Its inertness arises from the rigidity of the ligand which results in a tight pitch.

A self-consistent theoretical model in a simultaneous multiple parameter least-squares fitting procedure is used to treat experimental data from nuclear magnetic resonance, electron paramagnetic resonance and nuclear magnetic resonance dispersion of monomeric and dimeric Gd(super 3+) complexes. It is found that a simultaneous treatment of data from the three techniques results in an improved definition of the many parameters affecting the proton relaxivity of Gd(super 3+) complexes. Findings show that further relaxivity gain for these complexes will be hampered by the slow water exchange rate on the complexes.

The exchange of water molecule with iridium(III) on the homoleptic mononuclear metal center (Ir(H2O)6)3+ involves an associative interchange mechanism. A negative volume and near-zero entropy of activation confirm the occurrence of this mechanism. This is the slowest water exchange of similar nature giving a rate constant of 1.1x10(super -10) s(super -1). The deprotonated (Ir(H2O)5(OH))2+ is more reactive than (Ir(H2O)6)3+. Water exchange on this species takes place through an interchange mechanism.

The proton relaxivity measurements for the water-soluble metallofullerenes, 60)(OH)(sub X) and 60)[C(COOH()sub 2)](sub 10) can be used as a reporter to probe the aggregation (or diaaggregation) characteristics of water-soluble fullerene materials in the presence of physiologically encountered agents. The important implications for the development of gadofullerene-based MRI contrast agents and biological or medical application of fullerene-based materials are presented.

A thermodynamic study is performed on ligand protonation and complex formation with regard to practical aspects of a safe application of [Fe(tpy-DTTA)2Gd2(H2O)4] as a magnetic resonance imaging (MRI) contrast agent. The synthesis and results on the structure and relaxivity of the Ru(super II) containing analogue of the Fe(super II)Gd(sub 3)(super II) complex is reported.

The reaction of (R)-BINOL with bis(pentafluorophenyl)-phosphorus bromide in the presence of triethylamine is studied. This study is based on the application of variable-temperature (super 1) H, (super 31) P, and (super 17O) NMR spectroscopy, variable-pressure (super 31) P and (super 17) O NMR spectroscopy, and also on simple model complex, density functional theory calculations.

The electron spin relaxation is due to the combination of a static and a dynamic zero field splitting that was developed and tested on experimental EPR data that extends beyond the electronic Redfield limit using Monte Carlo simulations. The first simultaneous analysis of (super 17)O NMR, (super 1)H NMR, and EPR relaxation data is presented using the rigorous approach of the electron spin relaxation.

The influence of internal motion on the relaxation of the water protons in Ln(super 111)DOTA-like complexes is detailed. The bound water internal motion also affects macromolecular complexes, but when the final effect when combined with the local motion of the chelating group should be generally less than what is observed for the monomeric species.

The energetic and geometry features of the inclusion process in aqueous solution of a range of diphenyl azo dyes were determined using a novel approach, to further understand the mechanisms involved in cyclodextrin inclusion reactions.

Examines the influence of internal motion in the relaxation of the water protons in Ln(III)-like complexes. Determination of the quadrupolar coupling constant of the bound water oxygen; Negativity of the water proton relaxivity; Ratio of the rotational correlation times for the Ln(III).