Monomethylmercury (CH3Hg+ and its complexes; hereafter referred to as MeHg) in the intracellular environment is known to be predominantly bonded to thiol-containing biomolecules but the identities of these target biomolecules remain unknown. Some evidence suggests that binding with glutathione acts as a detoxification mechanism for MeHg, while binding with L-cysteine permits MeHg transport across the blood–brain barrier resulting in neurotoxicity. However, the occurrence of these complexes in biological tissues has not been confirmed analytically, and little is known about their kinetic stability. In this thesis, methylmercury L-cysteinate (CH3HgCys) and methylmercury L-glutathionate (CH3HgGlu) were synthesized and structurally characterized by proton nuclear magnetic resonance (1H NMR), electrospray ionization mass spectrometry (ESI-MS), and X-ray crystallography. A new analytical method was developed combining high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICPMS). The method was capable of separating and analyzing CH3HgCys and CH3HgGlu complexes, as well as CH3HgX and inorganic HgX (X = H2O, OH-, or Cl-), with detection limits at the sub-micromolar levels. Using a new enzymatic hydrolysis method to isolate MeHg species in biological tissues, the HPLC-ICPMS method was successfully applied for the determination of MeHg speciation in the muscle tissue of dogfish (Squalus acanthius). These results provide the first analytical evidence for the presence and dominance of CH3HgCys in fish muscle. The analytical method was also used to study the kinetic stability of CH3HgCys and CH3HgGlu under a range of environmental and intracellular conditions. In general, CH3HgGlu was more stable than CH3HgCys under light exposure or darkness. The stability of both compounds decreases dramatically with increasing ionic strength (I). Half-life of CH3HgCys decreases from 34.1 h (I = 0.01 M) to 5.9 h (I = 0. 5 M) and the half-life of CH3HgGlu decreases from 259 h (I = 0.01 M) to 35.9 h (I = 0. 5 M). Suggesting major differences in their cycling in freshwater (I < 0.01M), seawater (I ≈ 0.7M) and body fluids (I ≈ 0.16 M). The analytical technique and the findings from this thesis research provide a new analytical framework for the study of MeHg speciation in natural waters, and the metallomics of MeHg in biological systems.

High resolution (< 0.005 cm−1) electronic spectra of the diatomic molecular ions 70GeH+ and 74GeH+ have been recorded using a fast ion beam irradiated by a cw tunable dye laser. Over 150 transitions between the ground X1∑ + state and near-threshold levels of electronic states correlating to the lowest dissociation asymptotes Ge+(2P3/2) + H(2S) and Ge+(2P1/2) + H(2S) were observed in the range 16500 cm−1 to 18500 cm−1. The majority of the lines arise from a 1π-1∑ transition, where the predissociated excited state levels lie between the fine structure dissociation limits (Feshbach Resonances). The lifetimes of the rovibrational levels are found to increase, then decrease, with increasing rotational quantum number. Evidence for triplet (multichannel) mixing is revealed through the observation of additional lines and proton nuclear hyperfine splittings. Experimental results are compared with predictions of the vibrational and rotational energy levels obtained from a numerical solution of the Schrodinger equation. Least squares fitting yields molecular constants for the 1∑and the 1π states. A new apparatus used to create jet-cold molecular ions in a fast ion beam is detailed. Preliminary results have been obtained for the b4∑− g ← a4πu transition of O+ 2 which allow a rotational temperature for the source to be calculated.

The technique of electron spin resonance was used to study the magnetic properties of a number of complex salts of 7,7' ,8,8'-tetracyanoquinodimethane (TCNQ) in order to obtain a more complete understanding of the electronic states in these materials. All but one of the cations used in the preparation of these compounds were divalent and their TCNQ complex salts exhibit magnetic behaviour characteristic of thermally accessible triplet excitons. Three of these compounds, 1,2-di(N-p-cyanobenzyl-4-pyridinium)ethylene (DCBP)-(TCNQ)3' 1,2-di(N-methyl-4-pyridinium)ethane (DMPA)-(TCNQ)4 (I), and 1,4-di(N-pyridinium)butane (DPB)-(TCNQ)4' were available as single crystals and could be studied in detail. Four of these, however, were only available in polycrystalline form and these were DMPA(TCNQ)4(II) and 1,2-di(N-alkyl-4-pyridinium)ethylene (DRPE)-(TCNQ)S' in which R equals n-propyl (P), n-butyl (B), and cyclohexyl (H). The existence of two phases (I and II) of DMPA(TCNQ)4' first indicated by the electrical data, was supported by the different magnetic behaviour observed in this work. The absolute magnitudes of the signal intensity for DPPE(TCNQ)S' DHPE(TCNQ)S and DMPA(TCNQ)4 (II) ,were found to be well described by an approximate solution to the Heisenberg Hamiltonian, which indicates an exciton band is present in these compounds. The absence of dipolar splitting and the high d.c. conductivity supports this interpretation. However, DMPA(TCNQ)4(I), DPB(TCNQ)4' DBPE(TCNQ)S and DCBP(TCNQ)3 gave results indicative of localised triplet excitons. The latter compound exhibits dipolar splitting, and information concerning the exciton dynamics could be obtained. These results were consistent with the conductivity data and, where available, the crystal structure determinations. The complex salt TPT(TCNQ)4 was available in single crystal form and contained the only trivalent cation studied in this work. The temperature independent signal intensity indicated that triplet excitons were not present, and this behaviour was typical of Pauli paramagnetism. This observation was consistent with the semi-metallic d.c. conductivity observed and was explained in terms of the high degree of disorder present, as indicated by the crystal structure determination.

This may be interpreted as evidence that the profile of sub-structure of the lambda 6614 DIB is skewed towards the red in these three sightlines (Sk -68°135, Sk -69°223 and Sk -69°243) to a greater degree than that found in the Galactic ISM. Compared to Galactic trends, the LMC DIBs are found to be weak with respect to the reddening and neutral potassium column density towards Sk -67°2 and Sk -68°135. This may be attributable to a combination of the high UV flux and reduced shielding of interstellar clouds due to the low metallicity of the interstellar gas of the LMC, and results in the destruction of DIB carriers by photodissociation and/or photoionisation. Relative to N(H I) the lambda 6284 DIB observed in four LMC sightlines is shown to be approximately 1/5 to 1/2 of its average strength in the Milky Way. This supports the idea that the metallicity and/or dust-to-gas ratio of the ISM is closely linked with the chemistry that governs the abundance of DIB carriers relative to N(H I). Variations in the N(Ca II)/N(Ti II) ratio are found over at least an order of magnitude in the LMC ISM, and are taken as evidence for significant variation in the Ca n/Ca m ionisation balance. Derived logarithmic titanium depletions are found to be relatively low in the six LMC sightlines studied, with values between approximately -0.8 and -1.9, which are similar to the levels of depletion generally seen in the warm, shocked interstellar medium of the Galaxy.

The quality of analytical data produced by geochemical laboratories has become progressively more important as complex decisions concerning the impact of development on the environment Public concern regarding the impact of resource, industrial, and agricultural development is placing greater pressure on the government to protect the environment (Zhou, 2013). The quality of such data is squarely dependent on adherence to quality control programs, which provide guidelines from which high quality, trustworthy data can be generated. A unique quality control program was developed and implemented at the NSERC-IRC Aqueous and Environmental Geochemistry Laboratory. This program: 1) accommodate samples from unique environments; 2) documents and maintains the high level of confidence in the data produced; 3) provides standard quality control protocols; and 4) ensures the continued training of staff. The evaluation of data produced during 2013 revealed the strengths and weaknesses of the laboratory methods through comparison with data quality objectives. The data produced by the laboratory during 2013 was evaluated and quality confirmed. It was determined that the results produced met the high standards required by the data quality objectives, with a few minor exceptions. The quality objectives were based on the end use of the data and consideration regarding the complex nature of the water samples collected from diverse geologic media. There was increased variability of results near the method detection limit of selenium, cadmium, and arsenic, although they still meet to standards required for water quality investigations. Investigations into variabilities will include re-evaluation of detection limits, identification of the source of discrepancy between the methods, and possible matrix interference. Protocols will continue to be monitored and changes to methods made when objectives are not achieved or there are changes in laboratory staff, equipment, or the specific requirements of the studies the laboratory supports.

The goal of this study was to explore the use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for a variety of human hair analyses. / Optimization of the inductively coupled plasma mass spectrometry (ICP-MS) operating parameters, radiofrequency (RF) power and carrier gas flowrate, for solid sample introduction showed more than one operating condition can (1) produce a statistically similar maximum elemental signal and (2) have statistically similar optimum signal-to-noise (S/N) ratios. The use of an internal standard was shown to increase the number of operating conditions with statistically similar optimum S/N ratios, and the value of S/N ratios. The high degree of precision exhibited by 34S along hair strands from the same individual (2 - 3 % hair strand to hair strand RSDs) suggests that sulphur may be a suitable internal standard for elements in hair. / The single and multi ablation detection limits (DLs) obtained for elements in powdered hair certified reference materials (CRMs) were similar to what was expected for biological materials using LA-ICP-MS. / The possibility of using LA-ICP-MS to depth profile elements in a hair strand was explored. With the correct operating conditions, LA-ICP-MS may be an effective analytical tool for depth profiling elements in a hair strand. / LA-ICP-MS was used to construct mercury calibration plots using powdered hair CRMs and calibrated hair strands having R2 values of 0.9775 and 0.9522, respectively. / Exogenous deposits lead to confusion in the interpretation of findings from hair. LA-ICP-MS was used to remove an artificial exogenous deposit from a hair strand.

Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 0939. Adviser: Ralph G. Nuzzo. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph. D.)--University of North Texas, Dec., 2009. / Title from title page display. Includes bibliographical references.

<p> Metal containing complexes have been used to catalyze various organic transformations for the past few decades. The success of several mononuclear catalysts led to transition metal catalysts used in pharmaceuticals, environmental, and industrial processes. While mononuclear complexes have been used extensively, bimetallic systems have received far less attention. Bimetallic or polynuclear sites are commonly found in metalloenzymes that perform elegant transformation in biological systems, underlying their significance. Inorganic chemists take inspiration from nature and design model bimetallic complexes to further study this cooperativity effect. A bimetallic platform offers many structural and functional differences such as the identity of the metal atoms and the bonding interactions between metals, which have been reflected in their unique catalytic ability and reactivity. </p><p> This dissertation encompasses work related to the computational study of metal-metal interactions of bimetallic systems, the ¹H NMR study of stereochemical and conformational changes in solution of <i> N,N'</i>-diarylformamidines, the synthesis of dizinc formamidinate complexes, and the synthesis and catalytic ability of dicopper formamidinate complexes. </p><p> In the first part, DFT calculations are used to study factors that influence metal-metal bond lengths in various complexes. Several experimentally obtained X-ray crystal structures were used as the basis for the study. Differences in metal-metal separations were investigated through various functionals, indicating the importance of charge, orbital interactions, and formal bond order. BH&amp;HLYP SDD/aug-CC-PVDZ geometry optimizations of octahalodimetalate anions Tc₂X₈^n- (X = Cl, Br; n=2, 3), Re₂X₈^2- (X = Cl, Br), and Mo₂Cl₈^4- reproduced M-M bond distance trends observed experimentally. The study demonstrated that the increase in &sigma; and &pi; bond strength resulted in the shortening in Tc-Tc bond distance from Tc₂X₈^2- to Tc₂X₈^3-, which was further supported by the short Mo-Mo bond in the Mo₂Cl₈^4- ion. This study was expanded further through the inclusion of [M₂Cl₄(PMe₃)₄]ⁿ⁺ (M = Tc, Re, n = 0-2) and [Mo₂E₄]^n- (E = HPO₄ or SO₄, n = 2-4), allowing a systematic study on the role of charge on the metal atoms. PBEO SDD/aug-CC-PVDZ calculations revealed that both formal bond order and formal charge on the metal atoms dictate the trends in M-M bond strength. </p><p> The second half of this dissertation focuses on the synthesis and characterization of bimetallic Zn- and Cu-formamidinate complexes. The stereochemical exchange of substituted <i>N,N'</i>-diarylformamidines were studied through ¹H NMR in various solvents. Alkyl substituents placed on the ortho positions were found to shift the isomeric equilibrium in solution through destabilization of the hydrogen-bond dimer evident in X-ray crystal structures. The Z-isomer of substituted <i>N,N'</i>-diarylformamidines is observed in CDCl₃, C₆D₆, and DMSO-d₆ when the ligands feature significant steric hinderance. Similar ortho substituted <i> N,N'</i>-diarylformamidines were also used to enforce steric interactions to limit the nuclearity of Zn-formamidinate complexes. Various dizinc formamidinate complexes were synthesized through direct and transmetalation routes. NMR and mass spectrometry were used alongside X-ray crystal structures to fully characterize the dizinc complexes. Dicopper formamidinates formed through a transmetallation route were synthesized and feature distinct short Cu^&hellip;Cu separations thought to be brought about by metalophillic interactions. Preliminary results suggest catalytic ability of dicopper formamidinates in cyclopropanation and aziridination of styrene with various diazo compounds. The catalytic activity suggests the formation of dicopper carbene and nitrene intermediates, of which only few published experimentally observed examples exist in the literature.</p><p>

The domain sizes of a range of diblock polymers have been measured using solid-state NMR spin diffusion experiments carried out under fast magic angle spinning (MAS). 1H-1H exchange spectra were acquired at a range of mixing times and the results displayed effects due to both intra-domain and inter-domain spin diffusion. By fitting the data to an initial rate approximation domain sizes and spin diffusion coefficients were calculated. Simulations were also carried out to determine the impact of T1 relaxation during the experimental mixing time. The spin diffusion coefficient of polystyrene has also been studied under a variety of different conditions. Increasing MAS rate caused a decrease in the spin diffusion coefficient and at the fastest spinning speeds the rate of spin diffusion was much reduced. Temperature changes were shown to have little effect on the spin diffusion coefficient. The incorporation of recoupling sequences into the experimental mixing time was also studied. Solid-state NMR was also used to study a selection of hydroxyapatite nanoparticle/organic dispersant molecule composite materials with potential biomedical applications. 1H-31P correlation experiments were used to investigate the interaction between the dispersant molecules and the surface of hydroxyapatite nanoparticles. The spectra suggested that the dispersant molecules containing polylactic acid interacted with the surface of the nanoparticle via the polymer chain. Whereas dispersant molecules with an aliphatic chain appeared to interact with the particle via their head group. The results from DNP spectra, which selectively enhanced the surface regions, also supported this conclusion.