This thesis reports a study of the chemical stability and coordination chemistry of several antitumour metallocenes Cp2MCl2 (Cp = h5-C5H5; M = Ti 1, V 2, Nb 3, Mo 4), as well as derivatives of Cp2TiCl2 1, with nucleic acids, nucleic acid constituents and proteins. These studies were carried out in order to identify the biologically active species and more fully understand the molecular level mechanism of action of the antitumour metallocenes, in particular Cp2TiCl2 1, which is currently undergoing phase II clinical trials. The interactions of Cp2MoCl2 4 with four oligonucleotides were studied by 1H and 31P NMR spectroscopy. In 50 mM salt solutions of Cp2MoCl2 4, hydrolysis of the halide ligands occurred to give a solution with pD -2, containing a species in which both Cp rings remain metal bound for 24 h. At pD -7, partial hydrolysis of the Cp rings (-30percent) occurred after 24 h. Addition of an aqueous solution of Cp2MoCl2 4 in 50 mM salt to the self-complementary sequence d(CGCATATGCG)2, maintaining the pD at 6.0-7.0, showed no evidence for the formation of a metallocene-oligonucleotide complex and only peaks arising from hydrolysis of Cp2MoCl2 4 were detected. A similar result was obtained in titration experiments with the single stranded sequence d(ATGGTA) at pD 6.5-7.0. However, at pD 3.0, new signals assigned to a molybdocene-oligonucleotide complex(es), which was stable for hours at pD 3.0, were detected; while at pD -7 the complex is destabilised and only peaks arising from hydrolysis of Cp2MoCl2 4 were detected. Titration experiments at low pD with Cp2MoCl2 4 and the dinucleotide dCG were consistent with formation of a complex arising due to coordination of molybdenum to guanine N7 and/or cytosine N3. The results obtained showed that stable oligonucleotide adducts were not formed in 50 mM salt at pD -7 and hence it is highly unlikely that formation of molybdocene-DNA adducts in vivo is the primary action that is responsible for the antitumour properties of Cp2MoCl2 4. The rate of hydrolysis of the aromatic rings of Cp2TiX2 (X equals Cl 1, OCOCH2NH3Cl 27) and the dimethylsubstituted derivatives (MeCp)2TiX2 (X equals Cl 34, OCOCH2NH3Cl 41), in aqueous solutions at pD 2-8 was studied by 1H NMR spectroscopy. Rapid hydrolysis of both the halide/glycine and Cp ligands in Cp2TiX2 (X equals Cl 1, OCOCH2NH3Cl 27) occurred and predominantly gave a precipitate at pD -7. In contrast, under the same experimental conditions, the predominant species present in aqueous solutions of (MeCp)2TiX2 (X equals Cl 34, OCOCH2NH3Cl 41) at pH 2-8 contained both MeCp rings metal bound. At pD < 5, Cp2TiX2 (X equals Cl 1, OCOCH2NH3Cl 27) and (MeCp)2TiX2 (X equals Cl 34, OCOCH2NH3Cl 41) formed similar complex(es) with purine nucleotides. However, at pD >5, stable adducts between nucleotides and Cp2TiX2 (X equals Cl 1, OCOCH2NH3Cl 27) were not formed. In contrast, (MeCp)2TiX2 (X equals Cl 34, OCOCH2NH3Cl 41) formed complex(es) with 5'-dAMP or 5'-dGMP, which were stable for 24 h. These results suggest that formation of stable chelates between (MeCp)2TiX2 (X equals Cl 34, OCOCH2NH3Cl 41) and nucleic acid constituents in vivo is possible. However, the methyl substituted derivatives 34 and 41 did not show any antitumour activity against EAT in mice when administered in either 10percentDMSO/90percentsaline or in water at pH 6.2-6.4, which suggests that the labile Cp-Ti bond present in Cp2TiCl2 1 is required for antitumour activity. The synthesis of a range of Cp substituted titanocene derivatives was investigated in an attempt to prepare derivatives with modified Cp stability in comparison to the methyl substituted derivatives. The synthesis of derivatives (CpCH2Y)2TiCl2 where Y equals ?CHO 43, ?CONMe2 44, ?NO2 45, (RCp)2TiCl2 where R equals ?COMe 46, ?COOMe 47 or ?CONMe2 48, (CpNMe2)2TiCl2 62 and (Cp(CH2)2NMe2)2TiCl2 63 was unsuccessful, due to the presence of coordinating substituents on the Cp rings and poor stability in polar, protic solvents. Hence, these derivatives were excluded from further studies. The rate of hydrolysis of the Cp rings of Cp2TiX2 (X equals Cl 1, OCOCCl3 22 and OCOCH2NH3Cl 27) in aqueous solutions, 10percentDMSO/90percentD2O and 100percent DMSO was monitored by 1H NMR spectroscopy. Rapid hydrolysis of both the carboxylate and Cp ligands of Cp2TiX2 (OCOCCl3 22 and OCOCH2NH3Cl 27) occurred in DMSO to give biologically inactive species. The rate of these reactions were concentration dependent as dilution of these samples with saline or water to give the therapeutic conditions of 10percentDMSO/90percentD2O slowed the hydrolysis chemistry. In contrast, samples of Cp2TiX2 (X equals Cl 1 and OCOCH2NH3Cl 27) dissolved in water, gave solutions containing the presumed antitumour active species in which the halide or glycine ligands have been hydrolysed but the Cp rings remain metal bound. Thus, charged X ligands may be incorporated into Cp2TiX2 and will give comparable activity to Cp2TiCl2 1 provided the samples are administered in water. The antitumour metallocenes Cp2MCl2 (M equals Ti 1, V 2, Nb 3, Mo 4) and the inactive derivative (MeCp)2TiCl2 34 were found to inhibit the relaxation of supercoiled plasmid DNA pBR322 by human topoisomerase II in vitro. These results implicated the inhibition of topoisomerase II in the mechanism of antitumour activity although there was no direct correlation between the in vitro results with biological activity against EAT in vivo. UV spectroscopy confirmed that the metallocenes Cp2MCl2 (M equals Ti 1, Mo 4) became associated with and were stabilised to hydrolysis by calf thymus DNA but not with human serum albumin. ICP-AES was used to measure the amount of metal associated with either DNA or human serum albumin after incubation with Cp2MCl2 (M equals Ti 1, Nb 3, Mo 4) and dialysis of these solution. The results confirmed that DNA stabilises or becomes associated with the metallocenes. However, errors associated with the ICP-AES measurements did not allow these results to be quantified. 1H NMR spectroscopy was used to show that the antitumour metallocene Cp2MoCl2 4 formed an adduct with glutathione 72 in the pH range 3-7 through the sulfur donor group. In comparison, the antitumour metallocenes Cp2MCl2 (M equals Ti 1, Nb 3) showed limited adduct formation with glutathione 72 at pH -3 and no adducts were detected at pH > 5.5.

The work reported here is a detailed study of the proton magnetic resonance in single crystals of CoCl₂∙6H₂O. This substance is paramagnetic at high temperatures and becomes antiferromagnetic at about 2.25°K. The proton resonance frequency is a measure of the total magnetic field at the positions of the protons, which is the vector sum of the applied magnetic field with the internal field produced by the surrounding magnetic ions. At room temperature a single line about 6 gauss wide is observed. This line splits into a number of components at liquid helium temperatures. The position and number of lines strongly depend on temperature and on the direction of the externally applied magnetic field. The maximum overall splitting at 4.2°K is about 150 gauss in a field of 5000 gauss. At, 2.1°K the maximum splitting observed is about 2500 gauss. From the resonance lines in the paramagnetic phase it was possible to calculate the direction cosines of one proton-proton vector. The resonance spectra in both phases were found to agree well with the theory predicting the positions of the resonance lines and their dependence on crystal orientation. The transition temperature T[subscript N] was measured as a function of applied field and crystal orientation using the proton resonance lines, since they are very sensitive functions of temperature near T[subscript N]. T [subscript N] is found to be a complicated function of the applied field and crystal orientation, which cannot be described by T[subscript N](H,) = T(0) - const. H², as predicted by the Weiss Molecular field theory. The transition takes place over a temperature region of about 10[power -2] °K, and effects due to short range order are observed just above T[subscript N]. The magnetic susceptibility in zero field was measured along the preferred axis of antiferromagnetic alignment. This, together with specific heat data from published literature, was used to show a mutual consistency between thermodynamic variables and T[subscript N] obtained by NMR. The sublattice magnetization in the antiferromagnetic phase was measured as a function of temperature. It is found to depend logarithmically on T[subscript N] - T, but is independent of applied field and crystal orientation. Further experiments are suggested, which would add greatly to the understanding of the magnetic behaviour of CoCl₂∙6H₂0. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Standard radio-frequency nuclear resonance spectroscopy techniques have been applied to study the fine structure of the proton magnetic resonance absorption line in single crystals of CoCl₂.6H₂O. Cobaltous Chloride is a paramagnetic crystal at high temperatures and becomes antiferromagnetic at about 2.29°K. The position and number of lines strongly depend on temperature and on the direction of the externally applied magnetic field. Fewer lines than the theoretical number of twenty-four were always observed. At room temperature the proton resonance at 12 Mc/sec. in a field of 2.82 K gauss consists of a single line about six gauss wide. A splitting of this line into a maximum of six components has been observed at liquid helium temperature. The maximum overall separation at 4.2°K is about 110 gauss. For each direction of the externally applied magnetic field the separation between the lines increases with decreasing temperature. The transition temperature is measured and effects due to short-range order above the transition are observed. Theoretical formulae for the positions of the component lines are developed by considering the two-proton spin system within a water molecule of hydration immersed in the homogeneous external field [formula omitted] H and the inhomogeneous time- averaged field of the cobalt ions. Measurements in the antiferromagnetic state have been partially completed. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The production of 1,2-Dichloroethane (1,2-DCA) exceeds 5.44 billion kg per year, and is higher than that of any other industrial halogenated chemical. Improper disposal practices or accidental spills of this compound have made it a common contaminant of soil and groundwater. 1,2-DCA has been classified as a priority pollutant by the Environmental Protection Agency owing to its toxicity, persistence and bioaccumulation in the environment. It has also been shown to have mutagenic and potential carcinogenic effects on animals and humans. Bioremediation is emerging as a promising technology for the clean-up of sites contaminated with chlorinated hydrocarbons. However, sites co-contaminated with heavy metals and 1,2-DCA may pose a greater challenge for bioremediation, as the former pollutant could inhibit the activities of microbes involved in bioremediation. Therefore, this study was undertaken to quantitatively assess the effects of heavy metals on 1,2-DCA biodegradation and to investigate the use of biostimulation, bioaugmentation, dual bioaugmentation, and biosorption for remediation of water co-contaminated with 1,2-DCA and heavy metals in microcosms. The combined effect of 1,2-DCA and the respective heavy metals on the microbial population and diversity was also investigated. The minimum inhibitory concentrations (MICs) and concentrations of the heavy metals (arsenic, cadmium, mercury and lead) that caused half-life doubling (HLDs) of 1,2-DCA as well as the degradation rate coefficient (k1) and half-life (t1/2) of 1,2-DCA were measured in two different wastewater types. An increase in heavy metal concentration from 0.01–0.3 mM, resulted in a progressive increase in the t1/2 and relative t1/2 and a decrease in k1. The MICs and HLDs of the heavy metals were found to vary, depending on the heavy metals and wastewater type. In addition, the presence of heavy metals was shown to inhibit 1,2-DCA biodegradation in a dose-dependent manner, with the following order of decreasing inhibitory effect: Hg2+ > As3+ > Cd2+ > Pb2+. For the bioremediation experimental set-up, 150 ml wastewater was spiked with 1,2-DCA (2.5 mM) and the respective heavy metal in air-tight serum bottles (Wheaton). The bottles were biostimulated, bioaugmented, dual-bioaugmented or undergoing biosorption. The microcosms were incubated at 25 °C and the 1,2-DCA concentration was measured weekly. Co-contaminated water undergoing biostimulation, bioaugmentation and, in particular, dual bioaugmentation were observed to exhibit higher degradation of 1,2-DCA in the presence of the heavy metal, compared to co-contaminated water receiving none of the treatments. Dual bioaugmentation, proved to be most effective, resulting in up to 60% increase in 1,2-DCA degradation after 4 weeks, followed by bioaugmentation (55%) and biostimulation (51%). In addition, an increase in the total number of 1,2-DCA degrading bacterial population was observed in the bioaugmentated microcosms compared to those biostimulated, which corresponds to an increased 1,2-DCA degradation observed in the bioaugmentated co-contaminated microcosms. Dominant bacterial strains obtained from the co-contaminated microcosms were identified as members of the genera, Burkholderia, Pseudomonas, Bacillus, Enterobacter and Bradyrhizobiaceae, that have been previously reported to degrade 1,2-DCA and other chlorinated compounds. Some of these isolates also belong to genera that have been previously shown to be resistant to heavy metals. PCR-DGGE analysis revealed variations in microbial diversity over time in the different co-contaminated microcosms, whereby the number of bands was reduced, the intensity of certain bands increased, and new bands appeared. Agricultural biosorbents (AB) were found to adsorb heavy metals effectively when utilized at a concentration of 2.5%, with the level of biosorption found to be dependent on the type of AB as well on the type of heavy metal present. OP proved to be the most efficient biosorbent for the heavy metals tested, followed by CNF, and corn cobs (CC) least efficient; therefore CC was not used in further bioremediation experiments. Both orange peel (OP) and coconut fibre (CNF) were found to be excellent at removing heavy metals from co-contaminated microcosms, with OP removing 14.59, 74.79, 60.79 and 87.53% of As3+, Cd 2+, Hg2+ and Pb2+, respectively, while 10.03, 40.29, 68.47 and 70.00% of As3+, Cd2+, Hg2+ and Pb2+, respectively, was adsorbed by CNF. Consequently, a higher degradation of 1,2-DCA was observed in the presence of OP and CNF, compared to the untreated control. It can be concluded that the remediation approaches utilized in this study proved effective in the bioremediation of water co-contaminated with 1,2-DCA and heavy metals and may provide the foundation for new and innovative treatment strategies for co-contaminated sites. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2011.

The aim is to develop intensive methods for producing powdered iron or titanium, by mixing melts containing chlorides with molten salt reducing Ca-CaCl2 and Na-NaCl. As a result of this work was the possibility of obtaining metallic iron powder and products containing nedovosstanovleniya titanium compound. Conducted microscopic, X-ray, mikrorentgenoskopicheskie and particle size analysis of powders obtained. To discover the causes of titanium nedovosstanovleniya that need to be addressed in the future. The developed method can improve the performance as compared with the Kroll method because the reduction process within the melt, and not only at the interface between the salt and metal phases. / Целью работы являлось разработка интенсивных способов получения порошкообразных железа или титана, при смешении расплавов содержащих их хлориды с расплавленными солевыми восстановителями Ca–CaCl2 и Na–NaCl. В результате проведенной работы была показана возможность получения порошкообразного металлического железа и продукта, содержащего недовосстановленные соединения титана. Проведены микроскопические, рентгенофазовые, микрорентгеноскопические и гранулометрические анализы полученных порошков. Вскрыты причины недовосстановления титана, которые необходимо устранить в будущем. Разрабатываемый способ позволяет увеличить производительность по сравнению с методом Кролла благодаря тому, что процесс восстановления протекает в объеме расплава, а не только на границе раздела солевой и металлической фаз.

The purpose of this work is to study the saturation of the sodium NaCl melt, dissolve the titanium rod, and restore TiCl2 in the electrolyte volume with a Na-NaCl melt to develop an electrochemical technology for producing titanium powders. To substantiate the electrode processes, an attempt was made to create reference electrodes for the systems under study. According to the published data, the equations of temperature dependences of the standard, conventional-standard and redox potentials and the concentration dependence of the equilibrium potentials of titanium in molten sodium chloride, which were used in the analysis of polarization curves, were calculated. The kinetics of electrode processes in a sodium chloride melt is studied when metallic titanium is dissolved in it and when sodium is deposited on the iron cathode. An explanation of the processes occurring at the electrodes is given. Powders of metallic titanium are obtained. / Целью данной работы является исследование насыщения расплава NaCl натрием, растворение титанового стержня и восстановление TiCl2 в объеме электролита расплавом Na-NaCl для разработки электрохимической технологии получения порошков титана. Для обоснования электродных процессов, предпринята попытка созданы электроды сравнения для изучаемых систем. По литературным данным рассчитаны уравнения температурных зависимостей стандартного, условно-стандартного и окислительно-восстановительных потенциалов и концентрационной зависимости равновесных потенциалов титана в расплавленном хлориде натрия, которые использовались при анализе поляризационных кривых. Изучена кинетика электродных процессов в расплаве хлорида натрия при растворении в нем металлического титана и при осаждении натрия на железном катоде. Дано объяснение происходящих на электродах процессов. Получены порошки металлического титана.