Massey Documents by Type
Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294
Browse
12 results
Search Results
Item From Gas Phase Observations to Solid State Reality: The Identification and Isolation of Trinuclear Salicylaldoximato Copper Complexes(MDPI (Basel, Switzerland), 2022-09-29) Roach BD; Forgan RS; Kamenetzky E; Parsons S; Plieger PG; White FJ; Woodhouse S; Tasker PA; Morazzoni FConditions have been identified in which phenolic aldoximes and ketoximes of the types used in commercial solvent extraction processes can be doubly deprotonated and generate polynuclear Cu complexes with lower extractant:Cu molar ratios than those found in commercial operations. Electrospray mass spectrometry has provided an insight into the solution speciation in extraction experiments and has identified conditions to allow isolation and characterization of polynuclear Cu-complexes. Elevation of pH is effective in enhancing the formation of trinuclear complexes containing planar {Cu3-μ3-O}4+ or {Cu3-μ3-OH}5+ units. DFT calculations suggest that such trinuclear complexes are more stable than other polynuclear species. Solid structures of complexes formed by a salicylaldoxime with a piperidino substituent ortho to the phenolic OH group (L9H2) contain two trinuclear units in a supramolecular assembly, {[Cu3OH(L9H)3(ClO4)](ClO4)} 2, formed by H-bonding between the central {Cu3-μ3-OH}5+ units and oxygen atoms in the ligands of an adjacent complex. Whilst the lower ligand:Cu molar ratios provide more efficient Cu-loading in solvent extraction processes, the requirement to raise the pH of the aqueous phase to achieve this will make it impractical in most commercial operations because extraction will be accompanied by the precipitation (as oxyhydroxides) of Fe(III) which is present in significant quantities in feed solutions generated by acid leaching of most Cu ores.Item Manipulating soil bioavailable copper as an innovative nitrate leaching mitigating strategy in New Zealand pastoral soils : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) in Soil Science, School of Agriculture and Environment, College of Sciences, Massey University, Palmerston North, New Zealand(Massey University, 2023) Matse, Dumsane ThembaUrine patches are the primary sources of nitrate (NO₃⁻ -N) leaching from pastoral dairy farms. Since NO₃⁻ -N is the product of nitrification, a clear understanding of the nitrification process is a vital step toward the development of effective and efficient mitigation approaches. The first step of ammonia (NH₄⁺) oxidation to hydroxylamine (NH₂OH) is catalyzed by the ammonia monooxygenase enzyme (AMO), and copper (Cu) is a co-factor in the activity of the AMO enzyme. Therefore, manipulating Cu bioavailability through the application of Cu-complexing organic compounds such as calcium lignosulphonate (LS) and co-poly acrylic-maleic acid (PA-MA) to soil could influence AMO activity and consequently limit the nitrification rate in soil. There are no published studies that have examined the effect of bioavailable Cu concentration changes on nitrification rate, ammonia-oxidizing bacteria (AOB) and archaea (AOA), and NO₃⁻ -N leaching. The overall aim of this thesis is to determine the significance of bioavailable Cu in the nitrification process in the context of developing novel Cu-complexing organic compounds to inhibit nitrification rate in pastoral soils. A soil incubation study was conducted to characterize the relationship between changes in soil bioavailable Cu concentration and nitrification rate. This study was conducted using three pastoral soils (Pumice, Pallic, and Recent soils) spiked with five Cu levels (0.1, 0.3, 0.5, 1, and 3 mg kg⁻¹). Treatments of Cu-complexing compounds were separately applied to each Cu level. The treatments were urea applied at 300 mg N kg⁻¹, urea + LS at 120 mg kg⁻¹, and urea + PA-MA at 10 mg kg⁻¹. Results show that increasing the added Cu concentration from 0.1 to 3 mg kg⁻¹ increased nitrification rate by 35, 22, and 33% in the Pumice, Pallic, and Recent soils, respectively. Application of LS and PA-MA significantly (P ˂ 0.05) decreased nitrification rate with the mean reduction being 59 and 56%, 32 and 26%, and 39 and 38% in the Pumice, Pallic, and Recent soils, respectively at Day 8 relative to the urea-only treatment. To further extend knowledge of the relationship between bioavailable Cu and the key nitrifying microorganisms in soils, a greenhouse-based pot trial using three soils (Pumice, Pallic, and Recent soils) planted with ryegrass and treated with synthetic urine applied at 300 kg N ha⁻¹ and three levels of Cu (0, 1, 10, 100 mg added Cu kg⁻¹) was established. Results show that AOB amoA gene abundance increased as a function of increasing added Cu from 1 to 10 mg kg⁻¹ but was inhibited at 100 mg added Cu kg⁻¹ in both Pallic and Recent soils. The effect of bioavailable Cu was not apparent in the Pumice soil. The increase in AOB amoA gene abundance positively correlated with nitrification rate in both the Pallic (r = 0.982, P < 0.01) and Recent soil (r = 0.943, P < 0.01) but not in the Pumice soil. There was no effect of increasing Cu concentration on AOA amoA gene abundance in all three soils. Results from both incubation and greenhouse pot trials provide strong evidence that Cu is an important trace element in the nitrification process and reducing Cu can reduce nitrification in soil. However, in order to definitively quantify this treatment effect, further field studies were necessary. Therefore, a field lysimeter study was conducted using Pumice soil (Manawatu climate) and Pallic soil (Canterbury climate). The following treatments were investigated to reduce NO₃⁻ -N leaching during late-autumn application; urine only at 600 kg N ha⁻¹, urine + PA-MA at 10 kg ha⁻¹, urine + LS at 120 kg ha⁻¹, urine + a split-application of calcium lignosulphonate (2LS at same rate, initial and after a month of first application), and urine + ProGibb SG (GA at 80 g ha⁻¹) + LS (GA + LS). Another set of treatment applications, urine only, urine + GA only, and urine + GA + LS, were applied mid-winter to both soils. The GA was applied to improve the effectiveness of these organic compounds during climatic periods of poor plant growth. Results showed that there was no significant reduction in mineral N leaching associated with the late-autumn application of both PA-MA and LS for the Pumice or Pallic soils. However, the application of 2LS reduced mineral N leaching by 16 and 11% in Pumice and Pallic soils, respectively, relative to urine-only. The late-autumn inclusion of GA increased the effectiveness of LS in both soils. This was confirmed by a significant reduction of mineral N leaching by 35% from both Pumice and Pallic soils. Mid-winter application of GA + LS significantly reduced mineral N leaching only in the Pumice soil (by 20%) but not in the Pallic soil relative to urine-only. In both late-autumn and mid-winter treatments application of the different Cu-complexing treatments did not have negative effects on pasture dry matter yield in either Pumice or Pallic soils. In this lysimeter study, the mechanistic effect of PA-MA and LS on reducing bioavailable, nitrification rate and AOB/AOA amoA gene abundance was not investigated. A second field lysimeter experiment was established using the Recent soil in Manawatu to explore the mechanism of Cu manipulation through the application of LS and PA-MA on nitrification rate, AOB/AOA amoA gene abundance, and mineral N leaching. The effect of combining organic inhibitors with GA on reducing mineral N leaching was also investigated. This study evaluated the same treatments used in the first lysimeter study and applications were again conducted at two different seasonal periods (late-autumn and mid-winter). The results showed that the effect of PA-MA and 2LS on bioavailable Cu corresponded with a reduction in nitrification rate and AOB amoA gene abundance. The effect of PA-MA and 2LS was associated with reduced mineral N leaching by values of 16 and 30%, respectively, relative to urine-only. The reduction in mineral N leaching induced by PA-MA and 2LS increased N uptake by 25 and 7.8% and herbage DM yield by factors of 11 and 8%, respectively, relative to the urine-only. The LS treatment did not induce a significant change of either bioavailable Cu or nitrification rate which corresponded to no significant effect on mineral N leaching. The late-autumn combination of GA + LS reduced mineral N leaching by 19% relative to urine-only, but there was no significant difference in mineral N leaching observed for the mid-winter application relative to urine-only. The overall results of this research show that bioavailable Cu is a vital trace element in the nitrification process and for AOB functioning in soil. Therefore, reduction in bioavailable Cu through the application of Cu-complexing compounds can inhibit nitrification. In this doctoral study, the application of Cu-complexing compounds (LS and PA-MA) showed potential to inhibit nitrification rate and subsequently reduce mineral N leaching in pastoral systems, but their efficacy depends on soil characteristics. Future work is recommended to investigate the effect of LS and PA-MA application on nitrous oxide emissions. Further research is recommended to investigate the short and long terms effects of these treatments on non-target soil microbiota.Item Thioether and related ligand complexes of copper : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science(Massey University, 1975) Palmer, Kevin CharlesThe dithioethers 2,5-dithiahexane (DTH) and 3,6-dithiaoctane (DTO) form the following stable copper (II) complexes; Cu(S͡S)X₂ where S͡S=DTH or DTO and X=Cl or Br, and also Cu(DTH)₂(BF₄)₂ The complexes Cu(DTO)₂(BF₄)₂ and Cu(DTO)(NO₃)₂.H₂O decomposed over a short period of time. The following copper (I) complexes were also prepared: [CuX)₂DTO]n where X=Cl or Br, Cu(DTO)I, Cu(DTH)Cl, [Cu(DTH)X]n where X=Br or I, [Cu(DTO)SCN]n and Cu(DTO)₂ BF₄. The complexes were characterised using infra-red spectroscopy, visible-U.V. spectroscopy, Raman spectroscopy, x-ray powder photography, conductivity and molecular weight measurements, and proton nuclear magnetic resonance spectroscopy. Some reactions were also carried out by displacement of the dithioethers with a variety of monodentate and bidentate ligands, e.g. pyridine, ethylenediamine, trimethylphosphine sulphide, sodium dimethyldithiophosphinate dihydrate, and triphenylphosphine which also forms an adduct with Cu(DTH) Cl to give Cu(DTH) (Ø₃P) Cl.Item A comparison of copper(I) and copper(II) bound to thioether ligands : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University(Massey University, 1975) Norris, Gillian EThe structures of Cu(II) (DTH)2(BF4)2 (where DTH = 2,5-dithiahexane) and Cu(I) (DTO)2BF4 (where DTO = 3,6-dithiaoctane) have been investigated by single crystal X-ray diffraction techniques. After full matrix least squares refinement of the structures, with anisotropic temperature factors for all non hydrogen atoms in the Cu(II) structure, and for all atoms larger than fluorine in the Cu(I) structure, the conventional R factor converged to a final value of 0.057 for the Cu(II) structure, and 0.082 for the Cu(I) complex. The dark red crystals of the Cu(II) complex belong to the centrosymmetric monoclinic space group P2 1/c. with a = 8.082(3)Å, b = 10.282(3)Å, c = 11.893(4)Å and β = 115.3 degrees. Two dithiahexane ligands and two BF4-ions were found to co-ordinate to the Cu(II) ion to form a tetragonally distorted octahedron, with four Cu(II)-S bonds averaging 2.317Å in length, and two longer Cu(II)-F bonds averaging 2.576Å. The four sulphur atoms are part of two five membered Cu(II)-S-C-C-S rings in which both carbons are on the same side of the plane containing the copper and sulphur atoms. The colourless crystals of the Cu(I) complex were obtained in the non-centric orthorhombic space group Pna2 1, with a = 14.581(2)Å, b = 13.421(2)Å and c = 10.781(2)Å. The molecules exist as discrete monomeric species, with no co-ordination of the BF4- ion to the metal ion. The two ligand molecules co-ordinate to the Cu(I) ion to form a distorted tetrahedron, with the S-Cu(I)-S angles varying between 94.0 and 121.1 degrees. The four Cu(I)-S bonds average 2.307Å in length, and hence are approximately equal to the Cu(II)-S bonds (within experimental error). The two five membered Cu(I)-S-C-C-S rings are both in a gauche conformation, with one carbon below the plane containing the Cu(I) and S atoms, and the other above. The BF4- ion was disordered and was refined using rigid group restrictions. Cu-S co-ordination is thought to occur in some copper containing oxidation-reduction proteins. The observation of similar Cu-S bond distances when Cu(I) and Cu(II) are co-ordinated to thioether ligands (resembling the side chain of the amino acid methionine) may therefore be of direct relevance to the copper co-ordination in such proteins.Item Magneto-structural correlations of iron-salicylaldoxime clusters : a dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry at Massey University, Turitea Campus, New Zealand(Massey University, 2015) De Silva, Dunusinghe Nirosha TharanganiThe syntheses and characterisation of polynuclear metal clusters using a series of derivatised salicylaldoxime ligands are described in this thesis. The polynuclear iron clusters contain metallic cores consisting of oxo-centred triangles. It was found that slight modifications of the phenolic oxime ligands can lead to metal clusters with different nuclearities, thus producing a variety of magnetic properties within the materials. The predominant building block in the complexes is a triangular [Fe3O(Rsao) 3]+ (R = alkyl derivative, sao = salicylaldoxime) unit which can self-assemble into more complicated arrays depending on reaction conditions. A number of ligands containing a single phenolic oxime unit has been synthesised. These ligands have been used to form di-iron (C1), hexairon (C2), and heptairon (C3) complexes. A second series of ligands containing two double-headed phenolic oxime units linked by diamine straps has been synthesised and fully characterised. Two copper complexes C5 and C7 were crystallised and pyridine also took part in coordination to the copper centres. Three of the iron complexes formed with double-headed oxime ligands are heptairon compounds. The heptairon compounds were all analogous in their iron coordination environment. The hexairon complex (C8) formed from a double-headed oxime was analogous to the complex C2 formed from a single-headed oxime ligand in its iron coordination environment. The tri-iron complex (C10) also contains a metaborate ion. In each case of the heptairon complexes and the hexairon complex, the metallic skeleton of the cluster was based on a trigonal prism in which two [ O] triangles are fastened together via three helically twisted double-headed oxime ligands. Each of these ligands is present as (L-2H) where the oximic and phenolic O-atoms are deprotonated and the amino N-atoms protonated, with the oxime moieties bridging across the edges of the metal triangles. The identity of the metal ion has a major impact on the nuclearity and topology of the resultant cluster. The magnetic susceptibility measurements of these iron complexes suggest the presence of strong antiferromagnetic interactions between the metal centres and the Mössbauer analyses confirm the oxidation state of all the iron centres is 3+. The CHN analyses and other general characterisation allowed verifying and / or modifying the formulae generated by the X-ray analyses.Item Investigations into the copper status of sheep grazing at different stocking levels : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University(Massey University, 1974) Stevenson, John RichardA series of experiments were conducted to investigate the possible role of copper in limiting animal production at high stocking rates. Copper and selenium were administered to 494 four-tooth Romney ewes grazing at two different stocking rates. A significant (p<0.Ol) increase of 0.74 kg in lamb weaning weight was attributable to the supplementation of both elements. A depression in clean fleece yield (P<0.05) and a small improvement in fleece crimp clarity (P<0.05) were associated with copper and selenium supplementation respectively. Although both these effects reach significance at the P 0.05 level, they are considered to be due to chance. A winter fall (p<0.01) in mean plasma copper level was recorded in the high-stocked ewes. Further investigations were undertaken in another flock of 550 Romney ewes. Factors influencing plasma, liver and wool copper were determined and relationships between plasma copper level and various fleece and body variables assessed. Period and stocking rate were both shown to significantly (p<0.05) affect mean plasma copper. No effect of lambing rank or age of ewe could be shown. A small stocking rate by age interaction was recorded (P< 0.05 but this is considered to have arisen by chance. Of eighty one correlation coefficients determined between plasma copper level and various fleece and body variables, only six were statistically significant (P<0.05). No biological basis could be found to account for those shown to be significant. They are considered to have arisen by chance. No effect of stocking rate on either ewe or 'dead' lamb liver copper level could be established. Monthly wool copper determinations indicated that the midwinter, pre-lambing sampling was significantly depressed. No effect of stocking rate, age of ewe, or breeding rank could be established. Significant (P<0.05) botween-shcep differences were apparent. Concurrent determinations of wool zinc indicated a marked depression due to both an increased stocking rate, and the onset of winter and/or pregnancy (P<0.0l). Older ewes had higher mean wool zinc values (P<0.05). Additional observations on the plasma samples collected in previous experiments were undertaken. Mean plasma zinc levels were found to be significantly (P<0.0l) depressed by both a higher stocking rate and the onset of winter and/or pregnancy.Item Aspects of the accumulation of cobalt, copper and nickel by plants : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry, Massey University(Massey University, 1980) Morrison, Richard StephenHyperaccumulation of heavy metals was studied with the intention of elucidating the mechanisms of tolerance of hyperaccumulator plant species. Two main areas are covered; cobalt and copper accumulation by plants from Shaba Province, Zaïre, and nickel accumulation by species of the genus Alyssum. In surveys of vegetation of metalliferous soils of Shaba, nine or ten new hyperaccumulators of cobalt were discovered along with eight or nine very strong accumulators. For copper, seven hyperaccumulators and five or six very strong accumulators were discovered. Some families contained a higher frequency of hyperaccumulators than others. There is also a difference in superorder classification of cobalt and copper hyperaccumulators on one hand and nickel hyperaccumulators on the other. Surveys of the genera Aeolanthus, Ipomoea and Pandiaka were made but only one new copper hyperaccumulator was found: no new cobalt hyperaccumulators were found. Several species had their abilities to accumulate confirmed. Pot trials on three hyperaccumulators Aeolanthus biformifolius, Haumaniastrum katangense and H. robertii, showed accumulation of cobalt but not the expected accumulation of copper. The uptake curve was of the exclusion-breakdown form. The limit of breakdown, for each metal, was similar from species to species. Cobalt was less readily excluded than copper. The tolerance tests showed that some species have individuals with greatly enhanced abilities to survive higher metal concentrationsthan is normal for that species, while other species have more uniform tolerances. There appears to be no requirement for large metal concentrations at germination and seeds germinate more readily in the absence rather than the presence of the metals. The distribution of cobalt and copper within leaf tissues, of five species, appears to be parallel within each species. For each metal, the distribution is parallel between different species with the exception of Buchnera metallorum. More detailed studies on cobalt in H. robertii showed the distribution to be even over the leaf area but with small anomalous regions of high concentration. The possibility that some of the cobalt was precipitated as oxalate crystals is considered. The water-soluble cobalt fraction ligand could not be identified but was not proteinaceous. It has a mass of 5,200 g per mole of cobalt. A survey of the genus Alyssum revealed thirty-four taxa as hyperaccumulators to add to the fourteen previously known. All the taxa are from section Odontarrhena. The geographical distribution of the hyperaccumulators is discussed as is the possible evolution of hyperaccumulators in subsections Compressa and Samarifera from non-accumulators within them. Studies of nickel accumulation by eleven Alyssum species and the closely related Bornmuellera tymphaea showed similar characteristics for all hyperaccumulators but two non-accumulators differed. A rise-to-saturation uptake form was noted. In the absence of nickel, cobalt could be accumulated with a similar uptake form. Cobalt accumulation in the presence of nickel is unknown. The rate of uptake is relatively rapid. The tolerance of hyperaccumulators to high nickel concentrations was confirmed in two types of tolerance tests; a substrate medium test and a solution test. The results from the two tests are compared. The distribution of nickel between the plant organs is discussed. The analysis of mineral elements in leaf material showed interesting differences between hyperaccumulators and non-accumulators for calcium, magnesium and manganese content but these could not be related to differing nickel concentrations. A similar find was made for glucosinolates. An organic acid survey was restricted by the non-identification of many acids. Separation of the nickel complexes was made. Identification of ligands involved in nickel complexatian was attempted but few positive results were found. Two ligands were common in significant quantities for all species studied. The results of these experiments were used to discuss possible evolution of hyperaccumulator species both in terms of their superorder distribution and their method of metal ion uptake. An equilibrium mechanism of uptake is proposed which involves a multiplicity of complexes for the ion absorbed. The mechanism differs from that which is commonly proposed for micronutrient elemental uptake.Item Studies on the synthesis and reactivity of copper thiolate and thioamide complexes : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University(Massey University, 1984) Bingham, Alistair Gavin CameronIn response to a clear need for a more systematic approach to the study of the interaction of copper with ligands containing the sulphhydryl group, or in thioamide tautomeric equilibrium with such, cuprous, cupric and mixed valence complexes of ligands containing a thiolate or thioamide moiety have been synthesised and characterised by spectroscopic, magnetic and crystallographic techniques. In certain cases their reactivity in aliphatic and aromatic nitrogen base solvents and nitromethane have been investigated. Full names for the ligand abbreviations appear at the end of the abstract and ligand structures may be found in Figures at the beginning of the appropriate chapter. The visible, esr and resonance Raman spectra of the type I, copper protein, azurin from Alcaligenes denitrificans, have been recorded and compared with other type I proteins. Through comparison with the spectral features of a series of cluster complexes [CuII2CuI10 (mmim)12(Y)4](X)2 (where Y = CH3CN or H2O, and X = BPh4 Cl04,PF6, CH3COO or OH), and [CuII6CuI8(mea)12Cl]Cl5.7H2O, the so-called "unusual" spectroscopic features of the type I proteins have been re-interpreted as being normal phenomena of a Cu(II)-thiolate interaction coupled with specific geometrical requirements. Investigation of the mbtH ligand system has led to the reformulation of a number of incorrectly formulated copper complexes as [Cu(mbtH)2Cl] or [Cu(mbt)] following successful removal of a disulphide contaminant. In support of such, similar cuprous compounds of general formula [Cu(LH)2X] (LH = etmbtH, X = Cl, Br, I; LH = mbtH, X = Br, I; LH = mmimH, X = Cl), [Cu(LH)X].xH2O (LH = mbimH, mpyH, phmtzH, Ph2PS2H, X = Cl, Br; LH = mmimH; X = Br) and [Cu(L)] (L = bimet, dimtdz, dipmim etmbt, mpy, phmtz) have been prepared from similar ligand systems. The interaction of a number of these complexes with pyridine led to oxidation of organo-sulphur to sulphate with the production of [Cu(py)4SO4].2H2O. This reaction is postulated to occur via two oxidising species [Cu(py)2OH)2] or [Cu(py)xO] depending on whether halides are present or absent in the reaction solutions. Similar sulphato species are seen when quinoline and 3-ethylpyridine are used as solvents. However, compounds of general formula [Cu(LH)2X] and [Cu(LH)X] yield the complexes [Cu(3-Mepy)3Cl] and [Cu(4-Mepy)4Cl2].H2O, from the solvents 3-methyl-pyridine and 4-methylpyridine respectively, which have been structurally characterised by X-ray crystallography. The cupric and mixed valence complexes [Cu(ttzH)3X2] (X = Cl, Br), [Cu(ttzH)2Br2], [CuIICuI3(ttz)5], [CuIICuI(mmim)(mmimH)2Cl2], [CuIICuI(mmimH)2Cl3], [Cu(mbim)2(H2O)(NH3)], [Cu(mbin)2(H2O)], [Cu(dipmim)Cl] and [Cu(etu)OH] have been prepared and characterised by visible, infrared, and esr spectroscopy. When [Cu(ttzH)3Br2] is refluxed in nitromethane, a new cuprous complex [Cu(tztdz)Br] is produced in which modification of the ttzH ligand to produce the new organic moiety tztdz has occurred, confirmed X-ray crystallography. Similarly the compounds [Cu(tztdz)Cl], [Cu(tztdz)Cl2] and [Cu(mimmimz)Cl2] are postulated from the interaction of [Cu(ttzH)3Cl2] and [CuIICuI(mmimH)2Cl3] with nitromethane. With reference to well-defined literature examples the technique of esr spectroscopy is shown to discriminate between equatorial donor atom sets of S4, S2O2, S2N2, SO3 and O4 on the basis of lineshapes and position of fundamental parameters. The new compounds synthesised: (CuIICuI2(dimetH2)(dimetH)3Cl], [CuIICuI3(dimetH2)3(dimetH)(ClO4)4], [CuIICuI3(dimtolH)5], [CuIICuI3(dimprolH)5], [Cu(mpoH2)(mpoH)(ClO4)], [Cu(phenylglyoxaldtsc)], [Cu(benzildtsc)]. H2O and [Cu(3-n-heptoxy-2-oxobutyraldehydedtsc)] have been assigned donor sets on the basis of their respective esr signals. Similarly this has been done for a number of unisolatible species produced in situ from interaction of various cupric salts with a number of sulphhydryl and thioamide containing ligands.Item Crystallographic and physicochemical studies on metal and anion substituted human lactoferrin : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry at Massey University(Massey University, 1992) Smith, Clyde AlexanderLactoferrin, isolated from human colostrum, is an 80 kDa glycoprotein capable of binding two ferric ions concomitantly with two carbonate anions. The protein consists of a single polypeptide chain folded into two similar halves, each of which bind one iron and one carbonate. It is a member of the transferrin family of proteins, which includes serum transferrin, an iron transport protein found in the blood, ovotransferrin from avian and reptilian egg-white and melanotransferrin expressed by human melanoma cells. These proteins have important roles in the transport of iron around the body and the iron-binding function of lactoferrin has implications for the health of breast-fed infants. Two lactoferrin complexes with copper substituted for both iron atoms and the other substituted with copper and an oxalate anion for one of the carbonate anions, have been prepared and crystallised, and the structures of both determined by X-ray crystallography to 2.1 Å resolution. Whereas in diferric lactoferrin, both anions are coordinated in a bidentate fashion to the two iron atoms, in the dicupric complex the carbonate in the N-terminal site is monodentate, resulting in a 5-coordinate copper geometry with an elongated apical ligand (=2.7 Å). In the second complex, oxalate replaces carbonate in the C-terminal half only. Analysis of the structure indicates that the extent of closure of the lobes has an important role in determining the stereochemistry at the metal binding site. In addition to the structural studies, the binding of a variety of other metal ions, including other transition metals, aluminium, the lanthanides and thorium have been investigated spectroscopically. All of these metal ions form 2:1 complexes with lactoferrin but with varying degrees of stability. Some binding constants for a number of the lanthanides have been estimated, firstly to provide a comparison with results obtained for serum transferrin and secondly to investigate the relationship between the size of the metal ion and the strength of binding. In the course of the investigation of the binding of the lanthanide ions, it was established that cerium interacts with lactoferrin to give a complex which slowly developes [sic] a brown colour after standing for a few days. This can be attributed to the slow oxidation of Ce(III) to Ce(IV). These results, when compared with earlier structural analyses on lactoferrin, show that the protein is very flexible and can accommodate other metals without altering it's [sic] overall structure to any great extent. The predicted binding of other metal ions, including vanadium and the lanthanides, is described based on a combination of the crystallographic and physicochemical studies.Item A systematic search for the global minimum structures of Cs, Sn and Au clusters and corresponding electronic properties : a thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Massey University, Albany, New Zealand(Massey University, 2007) Assadollahzadeh, BehnamClusters of atoms or molecules form the building blocks of nanoscience and are regarded as a new type of material, as they constitute a bridge between microscopic and macroscopic forms of matter. The experimental and quantum theoretical study of structures, chemical and physical properties and reactivities of nanoclusters represents an innovative and very active field of research, which has resulted in a wide range of applications. Independent of the model used to describe the bonding in these clusters, one of the prime objectives is to find the geometrical arrangement of the atoms or molecules, for a given cluster size, which corresponds to the lowest energy on the potential energy hyper-surface, the global minimum. In order to find such an arrangement, a density functional theory based genetic algorithm code, which is rooted in the Darwinian evolution concept of the survival of the fittest, is developed and utilized to systematically search for the global minimum isomers of homo-nuclear clusters consisting of up to twenty atoms of cesium, tin, gold and of nine atoms of copper. The performance of this algorithm is excellent as numerous energetically lower-lying cluster isomers (compared to those reported in the literature) are found. Extensive valence basis sets together with energy-consistent scalar-relativistic pseudopotentials are employed to optimize the geometry of these clusters and to calculate their electronic properties accurately at the density functional level of theory. Moreover, in collaboration with the Technische Universit??t Darmstadt, the mean static polarizability of tin clusters are measured by a beam deflection method. The qualitative agreement between measured and calculated dipole moments and static electric dipole polarizabilities of tin clusters up to twenty atoms is satisfactory, thus confirming the accuracy of the theoretical models used in this work. Furthermore, the performance of density functional theory in the field of metallophilicity is investigated for dimeric and trimeric [X-M-PH3] compounds (X = Cl, Br, I; M = Cu, Ag, Au) and it is found that the metallophilicity decreases down the group 11 elements of the periodic table of elements.