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Some of the material in is restricted to members of the community. By logging in, you may be able to gain additional access to certain collections or items. If you have questions about access or logging in, please use the form on the Contact Page.
Studies of lanthanide interactions with polyoxometalates: Evaluation as magnetic resonance imaging agents
Description:
A series of lacunary (XM$\sb{11}$O$\sb{39}\sp{\rm n-}$ and P$\sb2$M$\sb{11}$O$\sb{61}\sp{10-}$) and plenary (SiW$\sb{12}$O$\sb{40}\sp{4-}$ and P$\sb2$M$\sb{18}$O$\sb{62}\sp{6-}$) polyoxometalates (POM) were synthesized, analyzed and... For elemental analysis of POM, quantitative methods were developed using ICP-AES for the determination of B, Si, Ge, P and Mo and atomic absorption spectroscopy for Na. The two-step procedure minimizes interelement interferences using... The thermodynamics parameters of complexation ($\Delta$G, $\Delta$H, and $\Delta$S) of Eu(III) with POM were studied at 1 M ionic strength. pK$\sb{\rm a}$ values for the lacunary POM indicate weak basicity with two protonations between... In addition, the $\sp7$F$\sb0 \to \sp5\rm D\sb0$ selective excitation spectra of Eu(III)-polyoxometalate complexes were evaluated qualitatively. Based on the number of peaks, the number of inner sphere H$\sb2$O molecules and the known... The Gd(POM)$\sb2$ complexes were kinetically unstable in Sprague-Dawley rat serum. In vitro challenges to Gd(POM)$\sb2$ by metal cations, DTPA, and DTPA-doped serum suggest instability in serum is due primarily to a transmetalation...
As of 2014, there is an expected 69, 000 metric tons of nuclear waste sitting in storage in the U.S. Little efforts have been made to deal with the radiotoxicity of the spent nuclear fuel (SNF). The problem arises from the complex mixture...
SYNTHESES AND STRUCTURAL STUDIES OF TRANSITION METAL COMPLEXES: PART I: 2,2'-BIPYRIDINE-N,N'-DIOXIDE. PART II: AMINOMETHANESULFONIC ACID AND 2-AMINOETHANESULFONIC ACID
SYNTHETIC AND PHYSICAL STUDIES OF MACROCYCLIC TRANSITION METAL COMPLEXES
Description:
The nickel (II) complex of the macrocyclic ligand 7, 16-dihydro-6, 8, 15, 17-tetramethyldibenzo{b, i}{1, 4, 11}-tetraazacyclotetradecinato (abbreviated Ni TMTAA) undergoes an oxidative dimerization reaction at the 7, 16-positions. The... In a related study, the sensitivity of anodic redox processes of Ni TMTAA to substitution on the macrocyclic ligand was investigated. A number of complexes derived from three patterns of substitution were prepared. Nine previously... The synthetic methodology developed for the substituted Ni TMTAA complexes was exploited for the preparation of a "capped" macrocyclic ligand. The iron(II) complexes of such a ligand have potential applications to reversible oxygenation...
Optical technology in biophysics has seen significant growth with development of high resolution techniques, like single-molecule FRET, to investigate biological structures under native conditions. Additionally, with the rise in gold...
In the 2018 Nuclear Posture Review, it has been emphasized that the continued production of nuclear materials is and will continue to be an essential part of American interest and policy. Necessarily, the cleanup and environmental...
Synthesis, characterization, and reactivity of group 6 metal (molybdenum and tungsten) complexes with porphyrin ligands
Description:
The structures, physical properties, and reaction chemistry of molybdenum (V) and tungsten (V) porphyrin complexes are investigated. The four, five-coordinate nitrido molybdenum (V) and tungsten (V) complexes MoN(TMP), MoN(TPP), MoN(TTP)... Quadruply bonded (W(TPP)) $\sb2$ and its reaction derivative WN(TPP) also have been synthesized. Diamagnetic tungsten dimer (W(TPP)) $\sb2$ shows the very similar spectroscopic patterns to those of (Mo(TPP)) $\sb2$. Temperature dependent...
The complex formation of UO(, 2)('+2), Ca('+2) and Th('+4) with halates, acetate and haloacetates has been studied by means of solvent extraction. The stability constants have been determined for UO(, Ca('+2) and Th('+4) with...
Metal flux synthesis is a useful technique for the discovery of novel intermetallic phases. The molten state enhances diffusion rates which improves rates of reaction. Reactions can proceed at lower temperatures, allowing for the...
The focus of this dissertation is to study the magnetic properties of several novel transition metal complexes, with particular emphasis on using SQUID magnetometry alongside electron paramagnetic resonance (EPR) and spectral simulations...
Flux synthesis is a useful method for the exploration and development of new tetrelide Zintl phases. Reactions of heavy divalent metals (A = Ca, Sr, Ba, Eu, Yb) with tetrels (Tt = Si, Ge, Sn) in Mg/Al flux mixtures produce charge...
Spin crossover (SCO) is a phenomenon of magnetic switching in transition metal complexes that can exist in two different electronic configurations, depending on the splitting of d-orbitals by the surrounding ligand field. About 90% of...
Understanding the chemical and biological innovation and evolution of the global ocean is pivotal in understanding the processes involved in the evolution and proliferation of early life on Earth and potentially habitable exoplanets....
Models for proton-coupled electron transfer based on ruthenium polypyridyl complexes
Description:
A family of ruthenium (II) complexes have been synthesized such that oxidation of the metal is coupled to an acid-base reaction at a remote site of a coordinated ligand. Proton-coupled electron transfer was evaluated based on cyclic...
BONDING STUDIES IN SOME TRANSITION METAL COMPLEXES: PART I, ORIGINS OF ELECTRIC FIELD GRADIENTS IN CESIUM TRICHLORO-NICKELATE(II), CESIUM TRICHLORO-CUPRATE(II), POTASSIUM TRICHLORO-CUPRATE(II); PART II, PARAMAGNETIC RESONANCE STUDY OF BONDING IN SOME PENTAMMINECHROMIUM(III) COMPLEXES
This dissertation seeks to determine the differences in the lanthanides and later actinides in non-aqueous media. Research in the f-elements is significantly understudied compared to the other metals of the periodic table. Even more so...
SYNTHESIS, CHARACTERIZATION, AND REACTIONS OF EARLY TRANSITION METAL COMPLEXES WITH A TETRAAZA-MACROCYCLIC LIGAND
Description:
My work involved the synthesis, physical characterization, and studies into the chemical reactivity of various titanium, vanadium and chromium complexes of the macro-cyclic ligand (C(, 22)H(, 22)N(, 4))('2-). These compounds were... The reaction of vanadyl acetate with the free ligand yields VO(C(, 4)), which was structurally characterized. The vanadyl oxygen may subsequently be removed to give an extremely reactive (very water and oxygen sensitive)... The analogous Ti(C(, 4))Cl(, 2) complex, prepared from TiCl(, 4) and the free ligand, is less readily hydrolyzed than V(C(, 2)(.)HCl. An X-ray diffraction analysis of the structure revealed cis coordination of... Studies of chromium reaction chemistry in this ligand are currently being completed. The chromium chemistry is complicated by sensitivity to H(, 2)O and O(, 2), leading to irreversibly oxidized and decomposition products. The reaction of... chelate ring to produce a pentadentate macrocyclic ligand can beisolated as the SCN('-) adduct, (' )Cr(C(, 4))(-C=N)NCS. (VBAR) CH(, 3)
Kinetics of dioxouranium(VI) ion reduction at polyelectrolyte - solution interfaces
Description:
The rates of reduction of the dioxouranium(VI) ion by 4, 4$\sp\prime$-dipropylsulfonate-2, 2$\sp\prime$ bipyridinium radical anions (ZV$\sp-$ radicals) were determined in the presence of the synthetic polyelectrolytes polyvinylsulfate (PVS... In addition, kinetic data for the reduction of the dioxoactinide(VI) ions, UO$\sb2\sp{2+}$, NpO$\sb2\sp{2+}$, and PuO$\sb2\sp{2+}$ by ZV$\sp-$ radicals were determined at pH 4.0. The measured rate parameters for the reduction of UO$\sb2...
Mechanistic studies of the group 6 metal carbonyl trifluorophosphines
Description:
The M(CO)$\sb{\rm 6-x}$(PF$\sb3$)$\sb{\rm x}$ complexes where M is Cr, Mo and W and x is 0 to 6 are known. The reactivity of both isomeric forms of the complexes x = 2 and 3 with $\sp{13}$CO and PF$\sb3$ were studied under purely thermal... isomer in large relative yields are discussed. These reactions were studied with packed column gas chromatography and infrared spectroscopy.
Competitive complexation studies of europium(III) and uranium(VI) complexation by aqueous orthosilicic acid
Description:
The environmental chemistry of actinide elements is of considerable interest since the release of actinides into the environment is considered the primary long-term hazard of nuclear waste disposal in geological repositories. While... Ligand competition experiments were employed to measure the stability constants of these f-element-orthosilicate complexes. Europium-orthosilicate complexation was studied by solvent extraction and laser-induced fluorescence spectroscopy... Speciation calculations show that europium orthosilicate complexes are important inorganic species for waters between pcH 6 and 7.5 that are in equilibrium with atmospheric carbon dioxide and contain at least 0.03 mM orthosilicate....
The substitution of the Group VIIB dimetal decacarbonyls with trifluorophosphine
Description:
Substitution of CO with PF$\sb3$ in the Group VIIB dimetal decacarbonyls has been studied under thermal and photolytic conditions. Substitution via photolysis is faster and results in the production of a greater number of isomers. Under...
Itinerant magnetism occurs in materials that exhibit a spontaneous polarization of the electronic structure due to the destabilization effect of a large peak in the Density of States at the Fermi level. This itinerancy is difficult to...
The first chapter serves as an introduction to nuclear science. Nuclear weapons are briefly discussed, but more focus is given to the intricacies of fission and traditional nuclear reactors. In order to better understand nuclear waste, a...
Two important applications of the f elements lie in the separation of the components comprising spent nuclear fuel, and f element use as radionuclides in nuclear medicine. Two ligand systems applying to each of these applications are...
Spin crossover (SCO) is a physical phenomenon where certain transition metal ions exhibit a change in their electronic configuration and magnetic state under the influence of external stimuli such as temperature, pressure, or light. SCO...
The pressure behavior of the actinides, like the rest of the chemistry of the actinides, is not well studied or understood. Chapter 1 gives a brief description of the prior work that has gone into studying the pressure behavior of the...
The actinide series is of great importance, possessing applications in clean energy, space travel, medicinal use, and even household smoke detectors. Despite everyday applications, our knowledge of the actinides is severely limited...
Some of the material in is restricted to members of the community. By logging in, you may be able to gain additional access to certain collections or items. If you have questions about access or logging in, please use the form on the Contact Page.
