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1
Jane, Reuben Thomas. "Cobalt(III) Complexes For Surface Engineering". Thesis, University of Canterbury. Chemistry, 2010. http://hdl.handle.net/10092/4424.
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This thesis addresses the potential for use of cobalt(III) complexes for functionalisation of lightly oxidised iron surfaces.
In Chapter 2 the preparation of cobalt(III) complexes of a series of ligands based on 1,1,1-tris(aminomethyl)ethane is described. The synthesis was approached in two ways. Firstly, preparation of functionalised triol molecules as precursors to functionalised triamine ligands was investigated. This approach utilised the Tollens condensation of aldehydes with formaldehyde. In a second approach, the functionalisation of tetrakis(aminomethyl)methane in which one amine arm has been differentiated was used. The tetraamine was reacted with benzaldehyde and reduced with borohydride ion to give a secondary amine molecule that was then functionalised using alkyl or aryl sulfonyl chloride molecules.
Chapter 3 describes the measurement of the binding of some cobalt(III) complexes to the surface of high surface area goethite. It was observed that complexes that have three exchangeable ligands bind more strongly than those with two exchangeable ligands. This is rationalised as being due to there being more bonds to the surface formed by complexes with three exchangeable ligands. It was also observed that complexes with three exchangeable ligands give greater surface coverage than those with two. This is likely due to the larger cross sectional area of the complexes with two exchangeable ligands in comparison to that of those with three, which blocks potential adjacent sites.
Preliminary experiments on the use of the contact angle, SEM, EDS and QCM to characterise complex binding are explored in Chapter 4 . The results from the EDS and QCM experiments show that these may be valuable tools for measuring this binding and the subsequent surface properties, but have not yielded detailed results at this point.
In Chapter 5 the use of cobalt(III) complexes as inhibitors of corrosion of iron in hydrochloric acid is investigated. All the complexes tested, even those that showed no binding to goethite surfaces, inhibit the corrosion to some degree. The level of inhibition is dependent on the complex, with [Co(tren)Cl2]Cl showing maximum inhibition of 81% and [Co(tame)Cl3] showing maximum inhibition of 53%. For some of the complexes, their concentration in solution over the course of the experiment was monitored by UV-vis. It was found that the complex disappears in a zero order reaction, the rate of which is dependent on the complex. However, the exact nature of this reaction is unknown. Furthermore, it was observed that inhibition of corrosion continues after the complex is no longer observed in solution. There is a difficulty in rationalising the inhibition being dependent on the complex identity, but not its continued presence in solution. Consequently, the mechanism of corrosion inhibition that explains all of these observations is still not known.
2
Telfer, Shane G. "The photochemistry of cobalt(III)-aminoacidato complexes". Thesis, University of Canterbury. Chemistry, 1999. http://hdl.handle.net/10092/7818.
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The photodecarboxylation reaction of Co(III)-aminocarboxylato complexes has been examined from several angles. Firstly, the currently accepted mechanism for the formation of [Co(bpy)(CHâ‚‚NHâ‚‚)]2+, following the UV photolysis of [Co(bpy)2(gly)]2+ (bpy = 2,2'-bipyridine, gly = glycinate), has been tested. A Co(II)-bound aminocyclopropylmethyl radical, with a lifetime of around 10^-4s, has been proposed as a reaction intermediate. This assertion was tested with the use of a radical clock, derived from chelated cyclopropylglycine. If a Co(II)-bound aminocyclopropylmethyl radical is formed, it will ring-open with rate constant k >= 10^7 s^-1 (298 K). This rate constant has been estimated on the basis of transition-state theoretical calculations and published data for related radicals.
The cyclopropyl group actually survived photolysis, and was found as cyclopropanecarboxaldehyde. This result implies that either the rate determining step has been wrongly assigned, or the proposed mechanism is incorrect.
Carbonyl compounds were also detected following the photolysis of [Co(bpy)2(aa)]^2+complexes, where aa = alaninate, valinate, phenylglycinate, and aminoisobutyrate. It was proposed that a Co-C-N metallacycle is formed briefly, but decomposes to give a Co(I) complex and an iminium ion. Hydrolysis of the latter fragment would account for the carbonyl compounds.
Secondly, some novel Co-C-N metallacycles have been prepared via the photodecarboxylation reaction. Cobalt(III) complexes with N,N-bis(2- pyridylmethyl)aminoacidate (amino acid = glycine, alanine, and cyclopropylglycine) ligands with 1,10-phenanthroline (phen) filling the remaining coordination sites, were prepared. Upon UV photolysis in aqueous solution, all three complexes yielded Co-CN metallacycles which were sufficiently stable to allow characterisation by conventional ^1H NMR, ^13C NMR, and UV-vis techniques. The solid state structure of the photolysis product of the glycinate derivative was determined by X-ray crystallography. These organometallic products eventually decompose, giving carbonyl compounds, free bis(2- pyridylmethyl)amine (bpa), free phen and the Co(II) ion. A peroxo-bridged Co(III) dimer, [Co(phen)(bpa)(02)Co(phen)(bpa)]^4+, crystallised from this mixture, and was characterised by X-ray crystallography.
Thirdly, the UV photolysis reactions of a series of [Co(bpy)2(aa)]^2+in DMSO solution were investigated. Carbonyl compounds are also produced in this solvent. The formation of trans(N)-[Co(aa)2(bpy)]+ complexes was also observed. This was ascribed to secondary (thermal) chemistry between dissolved molecular oxygen and some of the photolysis products: free amino acid, free phen, and Co(II). This same mixture gave rise to the [Co(bpy)3]3+ ion in aqueous solution. This difference was rationalised on the basis of the equilibria of the various [CoII(aa)x(bpy)y]^(2-x)+ complexes in the different solvents, and the potentials at which they are oxidised.
3
Sun, Lihui. "Synthesis and reactivity of some cobalt-, phosphorus-chiral cobalt(III) complexes". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ34235.pdf.
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Ernst, Margot Christiana. "Ab initio calculations on chiral cobalt (III) complexes". Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/27429.
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5
McClintock, Lisa F., e n/a. "Studies of cobalt(III) complexes containing tripodal tetraamine ligands". University of Otago. Department of Chemistry, 2008. http://adt.otago.ac.nz./public/adt-NZDU20080505.142115.
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The new Co(III) carbonate complexes [Co(uns-penp)(O₂CO)]ClO₄�H₂O and [Co(trpyn)(O₂CO)]ClO₄, containing tripodal tetraamine ligands, have been synthesised and characterised by microanalysis, �H, ��C and ⁵⁹Co NMR, mass spectrometry (MS) and UV-vis spectroscopy. In addition, the ⁵⁹Co NMR spectra have been obtained for two series of [Co(N₄)(O₂CO)]⁺ complexes containing aliphatic (N₄ = tren, baep, abap, trpn) and pyridyl (N₄ = tpa, pmea, pmap, tepa) tripodal tetraamine ligands and the complex [Co(dppa)(O₂CO)]⁺. The ⁵⁹Co NMR signal increases as [Delta] decreases, indicating there is less electron density at the Co(III) nucleus as the metal-ligand orbital overlap becomes poorer. A linear relationship was found to exist between the [Delta] for the individual complexes and their ⁵⁹Co NMR chemical shifts which follows the relationship: [Delta] = 29 174 + -0.89363 x [delta](⁵⁹Co)
For the two series of [Co(N₄)(O₂CO)]+ complexes, plots of the magnetogyric ratio (γ) and [lambda][max] have y-intercepts that do not accurately correspond to the magnetogyric ratio of the bare cobalt nucleus (γ₀(Co)). This is due to the deviation of the complexes from pure octahedral symmetry. A fluxional process in the complex [Co(pmea)(O₂CO)]⁺ was investigated using variable temperate (VT) NMR. This was found to involve the inversion of a six-membered chelate ring about a pseudo mirror plane with a [Delta]G[double dagger] of 58 kJ mol⁻� at 25 �C. Mass spectra have been obtained for all the [Co(N₄)(O₂CO)]⁺ complexes, and these show a common fragmentation pattern for all the complexes except [Co(trpn)(O₂CO)]⁺, where CO₂ is lost from the molecular ion to give a [Co(N₄)O]⁺ adduct. Single crystal X-ray structural analyses were performed on [Co(abap)(O₂CO)]ClO₄ (orthorhombic, Pca2₁, a = 15.9744(11) Å, b = 8.6200(6) Å, c = 21.8568(15) Å, α = β = γ = 90�, Z = 8, R1 = 0.0350, wR2 = 0.0902), [Co(trpn)(O₂CO)]ClO₄�H₂O (monoclinic, P2₁/c, a = 11.9510(19) Å, b = 12.0740(19) Å, c = 12.917(2) Å, β = 117.56(4)�, α = γ = 90�, Z = 4, R1 = 0.0476, wR2 = 0.1188), [Co(tpa)(O₂CO)]ClO₄�2H₂O (triclinic, P-1, a = 16.2298(5) Å, b = 17.2291(5) Å, c = 17.3393(5) Å, α = 106.760(1)�, β = 92.809(1)�, γ = 108.004(1)�, Z = 8, R1 = 0.0349, wR2 = 0.0799), [Co(uns-penp)(O₂CO)]ClO₄�H₂O (triclinic, P-1, a = 6.7544(3) Å, b = 11.5523(5) Å, c = 12.3201(6) Å, α = 73.397(2)�, β = 89.749(2)�, γ = 84.551(2), Z = 2, R1 = 0.0277, wR2 = 0.0842) and [Co(trpyn)(O₂CO)]ClO₄ (monoclinic, P2₁/n, a = 12.2777(5) Å, b = 11.9322(4) Å, c = 27.9622(11) Å, β = 100.082(2)�, α = γ = 90�, Z = 8, R1 = 0.0435, wR2 = 0.1130).
Rates of acid hydrolysis of [Co(N₄)(O₂CO)]⁺ (N₄ = baep, abap, trpn, tpa, pmea, pmap, tepa, uns-penp, dppa, trpyn, Me₃-tpa) complexes were measured by stopped flow or UV-vis spectroscopy (I = 1.0 mol L⁻�). The product of acid hydrolysis of [Co(pmea)(O₂CO)]⁺ has been indentified by X-ray crystallography as [Co(pmea)(OH₂)₂]�⁺ (triclinic, P-1, a = 9.7065(5) Å, b = 15.5645(8) Å, c = 11.5740(5) Å, α = 84.660(1)�, β = 123.255(1)�, γ = 104.283(1)�, Z = 2, R1 = 0.0402, wR2 = 0.1009). The acid hydrolysis reactions of the [Co(N₄)(O₂CO)]⁺ complexes containing aliphatic (N₄ = baep, abap, trpn) tripodal tetraamine ligands and [Co(tpa)(O₂CO)]⁺ and [Co(Me₃-tpa)(O₂CO)]⁺ have been investigated over the range [H₃O⁺] = 0.10 - 1.0 mol L⁻� Three processes were observed for the hydrolysis of [Co(baep)(O₂CO)]⁺, [Co(abap)(O₂CO)]⁺ and [Co(trpn)(O₂CO)]⁺ at all [H₃O⁺]. The first and second processes were thought to be [H₃O⁺] dependent, while the third was fit to a first order exponential decay and was [H₃O⁺] independent (k[obs] ~ 4.2 x 10⁻� s⁻� for [Co(baep)(O₂CO)]⁺, 3.8 x 10⁻� s⁻� for [Co(abap)(O₂CO)]⁺ and 3.5 x 10⁻� s⁻� for [Co(trpn)(O₂CO)]⁺). However, none of the processes could be confidently assigned to a step in the acid hydrolysis mechanism. The data obtained from the studies of [Co(tpa)(O₂CO)]⁺ and [Co(Me₃-tpa)(O₂CO)]⁺ showed a single first order [H₃O⁺] dependent process which was fit to the following expression: k[obs] = (k₁K[H₃O]⁺)/(1 + K[H₃O]⁺
This gave k₁ = 5.8 x 10⁻⁴ � 2.3 x 10⁻⁴ s⁻� and K = 0.13 � 0.06 L mol⁻� for [Co(tpa)(O₂CO)]⁺ at 25 �C and k₁ = 6.0 x 10⁻⁵ � 2.0 x 10⁻⁶ s⁻� and K = 0.38 � 0.02 L mol⁻� for [Co(Me₃-tpa)(O₂CO)]⁺ at 50 �C. Both values of K indicate that protonation of chelated carbonate is far from complete at [H₃O⁺] = 1.0 mol L⁻�. Comparative rates of acid hydrolysis at [H₃O⁺] = 6.0 mol L⁻� were obtained for the complexes [Co(tpa)(O₂CO)]⁺ (k[obs] = 1.79 x 10⁻� s⁻�, 25 �C), [Co(pmea)(O₂CO)]⁺ (k[obs] = 1.8 x 10⁻⁵ s⁻�, 25 �C), [Co(pmap)(O₂CO)]⁺ (k[obs] = 2.5 x 10⁻⁵ s⁻�, 50 �C), [Co(tepa)(O₂CO)]⁺ (k[obs] = 4.3 x 10⁻⁵ s⁻�, 25 �C) and [Co(trpyn)(O₂CO)]⁺ (k[obs] = 1.3 x 10⁻⁴ s⁻�, 50 �C) and at [H₃O⁺] = 1.0 mol L⁻� for the complexes [Co(uns-penp)(O₂CO)]⁺ (k[obs] = 2.9 x 10⁻� s⁻�, 25 �C) and [Co(dppa)(O₂CO)]⁺ (k[obs] = 2.7 x 10⁻⁴ s⁻�, 25 �C). The vast differences in the rates of acid hydrolysis can be rationalised on a steric basis. Bulkier ancillary ligands impede the direct protonation of an endo oxygen atom, or the transfer of a proton from the exo to an endo oxygen atom.
The chelated bicarbonate complex [Co(trpyn)(O₂COH)]ZnCl₄�3H₂O has been synthesised and characterised by microanalysis and X-ray crystallography (orthorhombic, Pbca, a = 18.1820(66) Å, b = 14.7256(44) Å, c = 19.6344(68) Å, α = β = γ = 90�, Z = 8, R1 = 0.0435, wR2 = 0.1130). The first products of direct metallion of coordinated carbonate, under both acidic and neutral conditions, have been isolated and characterised by microanalysis and IR spectroscopy. The X-ray crystal structures of the bimetallic complexes [Co(Me-tpa)O₂COZnCl₃]�H₂O (triclinic, P-1, a = 8.262(1) Å, b = 11.290(1) Å, c = 13.766(2) Å, α = 95.314(4)�, β = 103.160(4)�, γ = 107.071(5)�, Z = 2, R1 = 0.0382, wR2 = 0.0940) and [Co(pmea)O₂COZnCl₃]�H₂O (triclinic, P-1, a = 8.2916(7) Å, b = 11.0999(11) Å, c = 14.0994(13) Å, α = 8.2916(7)�, β = 102.607(4)�, γ = 108.600(4)�, Z = 2, R1 = 0.0347, wR2 = 0.0770), and the trimetallic complex [(Co(trpyn)(O₂CO))₂Zn(H₂O)̀₄](ZnCl₄)₂�3H₂O (monoclinic, P2₁/c, a = 20.9734(17) Å, b = 17.3712(12) Å, c = 15.7635(13) Å, β = 111.376(4)�, α = γ = 90�, Z = 4, R1 = 0.0235, wR2 = 0.0517) have been obtained. In addition, the X-ray crystal structures of the complexes [Co(trpyn)(O₂CO)](Zn(OH)₂Cl₃)�4H₂O (triclinic, P-1, a = 7.4962(7) Å, b = 13.4019(11) Å, c = 13.6887(11) Å, α = 74.631(4)�, β = 82.893(4)�, γ = 82.324(4)�, Z = 2, R1 = 0.0268, wR2 = 0.0638) and [Co(tepa)(O₂CO)]₂(ZnCl₄)�3H₂O (triclinic, P-1, a = 9.9250(10) Å, b = 15.5561(13) Å, c = 15.8730(16) Å, α = 89.545(4)�, β = 85.019(5)�, γ = 72.714(4)�, Z = 2, R1 = 0.0291, wR2 = 0.0722) were obtained. These two complexes were synthesised under analogous conditions to the bi- and trimetallic complexes. However, in these cases metallation of chelated carbonate did not occur.
DFT calculations have been used to calculate the relative energies of pairs of geometric isomers of [Co(N₄)(O₂CO)]⁺ complexes (N₄ = baep, abap, pmea, pmap, dppa, Me-tpa, Me₂-tpa). In all cases, except that of [Co(Me-tpa)(O₂CO)]⁺, the calculations correctly predict that the experimentally observed isomer is lower in energy. An electronic study on two series of [Co(N₄)(O₂CO)]⁺ complexes containing pyridyl (N₄ = tpa, pmea, pmap, tepa) and Me-pyridyl (N₄ = tpa, Me-tpa, Me₂-tpa, Me₃-tpa) tripodal tetraamine ligands correctly reproduces the observed trends in ⁵⁹Co NMR chemical shift and [Delta] values. A molecular orbital analysis of the two series of complexes shows that there is no significant difference between the highest energy occupied orbitals with the largest contribution from the coordinated oxygen atoms. Bond decomposition analyses of the two series of complexes indicate that there is also no difference in total bond energies. These results indicate that there is no electronic explanation for the large differences in reactivity towards acid that is observed experimentally.
The first mononuclear complex containing chelated hydrogen phosphate, [Co(pmea)(O₂PO₂H)]ClO₄, has been synthesised and characterised using microanalysis, �H, ��C, ��P and ⁵⁹Co NMR, UV-vis spectroscopy and X-ray crystallography (monoclinic, P2₁/c, a = 8.7017(17) Å, b = 27.639(5) Å, c = 9.586(2) Å, β = 112.818(9)�, α = γ = 90�, Z = 4, R1 = 0.0443, wR2 = 0.1076). The X-ray crystal structure of [Co(pmeaH)(OH₂)Cl₂](CoCl₄)�H₂O (orthorhombic, P2₁2₁2₁, a = 12.6354(3) Å, b = 12.6354(3) Å, c = 15.8261(11) Å, α = β = γ = 90�, Z = 4, R1 = 0.0397, wR2 = 0.0954), in which the pmea ligand is coordinated in a hypodentate fashion, was also obtained. [Co(pmeaH)(OH₂)Cl₂](CoCl₄)�H₂O is thought to be an impurity in crude samples of [Co(pmea)Cl₂]Cl. The pK[a] of [Co(pmea)(O₂PO₂H)]⁺ was determined to be 4.99 � 0.02 by potentiometric titration. A ring inversion fluxional process, analogous to that observed for [Co(pmea)(O₂CO)]⁺, was found by VT-NMR to have a [Delta]G[double dagger] of 60 kJ mol⁻� at 35 �C. A ��P NMR spectrum, taken after the solution was left standing for approximately three hours, showed evidence of cleavage of the hydrogen phosphate chelate via a bimetallic hydrolysis mechanism. Attempts were also made to synthesise Co(III) complexes containing chelated phosphate ester ligands (monomethyl phosphate and monophenyl phosphate), with pmea as the ancillary ligand. ��P NMR spectra of the crude samples indicate that the monomethyl phosphate moiety is chelated to Co(III) (��P [delta] = 21.05 ppm). However, it is unclear whether the monophenyl phosphate is chelated or bridging between two Co(III) ions (��P [delta] = 14.36 ppm).
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McCombs, Michelle. "A 59-Cobalt NMR Investigation of the Hydrogen/Deuterium Exchange Kinetics in Cobalt(III) Complexes". TopSCHOLAR®, 2003. http://digitalcommons.wku.edu/theses/554.
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Currently, the hydrogen/deuterium exchange kinetics in cobalt(III) complexes are being investigated. In the presence of deuterated solvents, (e.g. D2 0 and CH3CH20D) the amine hydrogens in the complexes are exchanged for deuteriums. For the hexaamminecobalt(III) ion, 19 isotopmers (H18D0 to HOD 18) are possible. For the tris(ethylenediammine)cobalt(III) ion, 13 isotopmers (HI 2D0 to HOD 12) are possible. Each hydrogen/deuteruim exchange causes a shift in the observed 59Co resonance of approximately 6 ppm. The rate constant of the hydrogen-deuterium exchange for the first H-D exchange has been determined as a function of solvent. When the chosen solvent is D20, the rate constant is 1.09 x 10° sec"1 for the hexaamminecobalt(III) ion. In methanol-d, the rate constant is 1.82 x 10"4 sec"'. Electronic effects of ligands have also been investigated. Experimental conditions (e.g., observation frequencies and solution parameters) and the representative NMR spectra are presented.
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Simonato, Jean-Pierre. "Chimie de coordination de la tétraméthylchiroporphyrine avec le fer(III), le cobalt(III) et le rhodium(III) : applications à l'analyse d'énantiomères d'amines, à la complexation énantiosélective d'aminoalcools, et à la catalyse d'aziridination asymétrique". Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10051.
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Des complexes metalliques de la tetramethylchiroporphyrine, de symetrie et possedant des groupements meso derives du biocartol, ont ete synthetises, caracterises, et utilises dans quatre axes de recherches. _la caracterisation du complexe bis-ethanol de la tetramethylchiroporphyrine de fer(iii), en solution et en phase solide, revele que ce compose presente un etat de spin inhabituel : le spin intermediaire pur (s = 3/2). _l'insertion d'un metal diamagnetique, le cobalt(iii), coordonnant les amines au cur de la porphyrine, a permis l'analyse qualitative et quantitative de la composition de derives d'amines par resonance magnetique nucleaire du proton. Cette methode s'est averee precise, fiable, rapide et tres facile d'utilisation. _l'addition de -aminoalcools sur cette meme molecule resulte en la complexation preferentielle d'un enantiomere. Les aspects cinetiques et thermodynamiques ont ete abordes, et une explication quant a l'enantioselectivite observee est avancee sur la base de liaisons hydrogene intramoleculaires de type c-h___o. _parmi differentes complexes de la tetramethylchiroporphyrine, ceux de fer(iii) et de manganese(iii) ont donne les meilleurs resultats pour la catalyse d'aziridination asymetrique, avec des exces enantiomeriques allant jusqu'a 57% pour le styrene. Un point remarquable est l'induction asymetrique opposee de ces deux catalyseurs, chacun favorisant la formation majoritaire d'un enantiomere.
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Wilson-Coutts, Sarah Mary. "The Synthesis and Configuration of Some Polydentate Amino Acid Complexes of Cobalt(III)". Thesis, University of Canterbury. Chemistry, 2009. http://hdl.handle.net/10092/2788.
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This thesis reports a study of polydentate amino acid complexes of cobalt(III). The complexes prepared during this project have been characterized by a range of techniques, including ¹³C{¹H} and ¹H NMR spectroscopy, UV-visible spectroscopy, infra-red spectroscopy, elemental analysis and single crystal X-ray structure determination. A total of seven single crystal X-ray structure determinations have been performed during these studies. The imino acid polydentate complex, [Co(Aim₂trien)]₂[ZnCl₄], was reduced to the corresponding amino acid complex, [Co(A₂trien)]Cl, where as many as ten diastereoisomers could be formed due to the formation of new stereogenic centres. The crude product of these reactions was a mixture of isomers, according to ¹³C{¹H} NMR data. These isomers were separated using ion-exchange chromatography. The major isomer (I1), a minor isomer (I2a) and a half reduced complex (I4a) from the [Co(A₂trien)]Cl reduction and separation experiment were characterised. The predominant isomers produced were found to have had the proton on the α-carbon atoms positioned on the amine face of each amino acid ligand fragment. To investigate the ratio of the isomers formed by the initial borohydride reduction, an isomerisation study of the major isomer of the [Co(A₂trien)]⁺ complex (I1) was performed. This study hoped to establish the degree to which the distribution of isomers was a result of dynamic equilibrium. Experiments on a small scale showed the initial isomer distribution to be similar to that obtained from the borohydride reduction reaction. However, prolonged exposure to the carbonate buffer (≈ two weeks) resulted in isomers not previously seen. Experiments on a large scale were performed to establish whether the results were consistent. The materials from both the two hour and two week experiments were mixtures of isomers by ¹³C{¹H} NMR spectroscopy and were separated using ion-exchange chromatography. ¹H NMR data of the two hour experiment showed only epimerisation of the amine proton adjacent to the α-carbon atom. Therefore the isomers produced from the isomerisation of I1 have the same configuration of the proton on the α-carbon atoms, which is on the amine face of each amino acid chelate ring. ¹H NMR data from the two week experiment resulted in new isomers not previously seen as both the amine proton and the proton on the α-carbon atom have been epimerised. The polyamine wrapping around the central metal ion may also have changed in some cases. It would appear, from the ¹H NMR data that the methyl group signals of these isomers fall in two distinct clusters; a cluster at δ 1.50-1.65 ppm and a cluster at δ 1.40-1.49 ppm. From these results, and the results of Chapter Two, it has been calculated that there is at least 92% facial selectivity for the amine face of the molecule during the initial borohydride reduction reactions. This may be due to a di-hydrogen bonding interaction between an adjacent amine proton and a hydride of the borohydride, which directs the attack. Following on from this study, a new range of imino and amino acid complexes were synthesised using different tetraamine and pentaamine cobalt(III) complexes. X-ray quality crystals of [Co(Aim₂2,2,3-tet)][ClO₄] and [Co(Aim₂2,3,2-tet)][ClO₄] were obtained and solved with assistance from Dr. Chris Fitchett and Dr. Jennifer Burgess. Borohydride reductions were performed on the [Co(Aim₂2,2,3-tet)]⁺ and [Co(Aim₂2,3,2-tet)]⁺ systems. The products were a mixture of isomers according to 1H and ¹³C{¹H} NMR spectroscopy. The results from the ¹H NMR experiments showed similarity between the [Co(A₂2,3,2-tet)]⁺ and [Co(A₂trien)]⁺ systems, where three major stereoisomers were present in solution. Analogous results for the asymmetric [Co(A₂2,2,3-tet)]⁺ system were also observed. Preliminary attempts have been made to separate these isomers using ion-exchange chromatography.
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Cai, Lezhen. "Mechanisms and salt effects in photoredox and quenching processes involving cobalt(III) complexes". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21925.pdf.
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Jewiss, H. C. "Some coordination complexes of cobalt(III) and some related X-ray crystallographic studies". Thesis, University of Southampton, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373933.
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Spicer, M. D. "Higher oxidation state complexes of group Vb and VIb donor atom ligands : Compounds with cobalt(III) and copper(III)". Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382971.
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Wang, Zekun. "La synthèse et la catalyse de complexes organométaliques de cobalt (III) de ligands chélateurs scorpionates". Electronic Thesis or Diss., Strasbourg, 2025. http://www.theses.fr/2025STRAF004.
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Cette thèse porte sur la synthèse et les applications catalytiques des complexes de cobalt(III) contenant des ligands chélatants de type scorpionate. Des ligands tris(pyrazolyl)borate (Tp) ont été utilisés pour former des complexes de cobalt présentant une diversité de propriétés structurelles et électroniques. Une exploration systématique de ces complexes révèle leur potentiel dans les transformations catalytiques, notamment dans les réactions de couplage carbone-carbone. En outre, le phénomène de spin-crossover observé dans les complexes de cobalt permet des transitions dynamiques entre les états de spin élevé et de spin faible, influençant de manière significative les mécanismes réactionnels et l’efficacité catalytique. Cette propriété facilite l’activation des substrats et des intermédiaires, tout en abaissant les barrières énergétiques des étapes clés de la catalyse. Ces caractéristiques permettent des voies réactionnelles efficaces dans des conditions douces, mettant en avant le potentiel du cobalt en tant que catalyseur multifonctionnel et durableThis thesis focuses on the synthesis and catalytic applications of cobalt(III) complexes containing scorpionate chelating ligands. Tris(pyrazolyl)borate (Tp) ligands were utilized to form cobalt complexes with diverse structural and electronic properties. Systematic exploration of these complexes reveals their potential in catalytic transformations, particularly in carbon-carbon coupling reactions. The spin-crossover phenomenon observed in cobalt complexes allows for dynamic transitions between high-spin and low-spin states, significantly influencing reaction mechanisms and catalytic efficiency. This property facilitates the activation of substrates and intermediates, lowering energy barriers in key catalytic steps. Additionally, the oxidation of cobalt to higher oxidation states enhances its catalytic performance. These features enable efficient reaction pathways under mild conditions, highlighting cobalt's potential as a multifunctional and sustainable catalyst
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Rocha, Beatriz Aline Riga [UNESP]. "Síntese de ligantes diimínicos para obtenção de complexos organocobalto(III) para polimerização radicalar mediada por cobalto". Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/149815.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Neste trabalho objetivou-se a síntese e caracterização de oito complexos de cobalto(II) que fossem aptos a atuarem como agentes controladores na Polimerização Radicalar Mediada por Cobalto do monômero acetato de vinila. Através da modulação da esfera de coordenação destes complexos com a alteração dos efeitos estéricos e eletrônicos promovidos pela coordenação de ligantes α-diiminas, buscou-se estabelecer parâmetros para propor a forma como estes complexos mediam a CMRP do referido monômero. Os complexos foram divididos em dois grupos, objetivando uma avaliação mais eficiente da forma como os efeitos estéricos e eletrônicos interferem na capacidade controladora dos mesmos. Após a variação sistemática das proporções molares entre complexo, iniciador e monômero encontrou-se na proporção [Co]/[AIBN]/[VAc] = 1/3,25/542 os resultados mais satisfatórios deste trabalho. O uso de DMSO fora prejudicial para os complexos 2a-c, porém fez com que os complexos 2d-h apresentassem melhorias, reduzindo seus valores de polidispersidade e aumentando as massas moleculares dos polímeros. O complexo 2b fora escolhido como o melhor controlador do grupo do efeito estérico, por reunir em si as características estérias e eletrônicas que o fizeram apresentar os menores valores de polidispersidade (Đmáx = 1,43). Com relação ao grupo de complexos do efeito eletrônico, fora o complexo 2f que, devido à maior estabilidade estrutural conferida ao complexo por seu substituinte cicloexil, apresentara as menores polidispersidades de seu grupo, entre 1,12 e 1,58.
This work aimed the synthesis and characterization of eight cobalt(II) complexes which could be able to act as controlling agents in vinyl acetate radical polymerization mediated by cobalt. By modulating the coordination sphere of these complexes, modifying the steric and electronic effects offered by the α-diimine ligands, we sought to establish parameters to propose how these complexes mediate the CMRP of vinyl acetate. The complexes were split in two groups in way to assess efficiently how the electronic and steric effects can affect the controlling capacity of the CoII(α-diimine).A systematic variation of the molar ratio such as [Co]/[initiator] and [Co]/[monomer] made it possible to choose [Co]/[initiator]/[monomer] = 1/3.25/542 as the ratio that provided certain level of control. The addition of DMSO was detrimental to the complexes 2a-c, but caused an improvement to the activity of complexes 2dh, reducing their polydispersity values and increasing the molecular weights of the polymers. Complex 2b was chosen as the best controller of the steric effect group, its steric and electronic characteristics made possible to reach the lowest polydispersity of its group (Đmax = 1.43).Regarding to the group of complexes of the electronic effect, it was the complex 2f that had the smallest polydispersity of its group, between 1.12 and 1.58, due to the greater structural stability conferred to the complex by its cyclohexyl substituent.
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Simon, Evelyne. "Etude des complexes cobalt(III)-cyclame-acétylacétonate : élaboration d'électrodes modifiées par des films de polypyrrole porteurs du site redox : co-cyclame". Brest, 1997. http://www.theses.fr/1997BRES2001.
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L'objectif de ce travail est la realisation d'electrodes modifiees, portant le site redox co#i#i#i(cyclame), par electropolymerisation de monomeres de pyrrole sybstitues en position 1 ou 3 par le complexe metallique. Le premier chapitre est consacre aux rappels bibliographiques concernant les electrodes modifiees, le polypyrrole et le cobalt-cyclame. L'etude de la nature du site catalytique choisi, co#i#i#i(cyclame), est exposee dans le chapitre 2. La structure du complexe co#i#i#i(cyclame)(acac)(bf#4)#2 a ete etablie sans abmiguite par diverses techniques spectroscopiques, electrochimiques et notamment par cristallographie. La synthese des monomeres de pyrrole est ensuite decrite dans le chapitre 3. Le cyclame est lie au pyrrole (en position n ou sur le carbone en position 3) par un chainon aliphatique greffe sur l'un des quatre atomes d'azote du macrocycle : 3-(cyclame-n-(ch#2)#5)pyrrole (1) et 1-(cyclame-n-(ch#2)#5)pyrrole (2). Les essais d'electropolymerisation et de catalyse sont detailles dans le chapitre 4. Le ligand (1) polymerise tres rapidement apres elimination du groupement protecteur de la fonction nh, le triisopropylsilyle ; ce qui rend difficile le depot du film de polyrrole a la surface d'electrode. La faible solubilite des complexes de cobalt(iii) avec le ligand (2) ne permet pas d'obtenir des films de qualite satisfaisante. En revanche les complexes cobalt(ii) avec ce ligand polymerisent plus facilement sur platine, or et carbone vitreux. Les resultats preliminaires obtenus lors des essais d'electrocatalyse montrent que les electrodes d'or et de carbone vitreux modifiees permettent de catalyser la reduction de certains substrats comme l'ion nitrate ou le dioxygene. Il est alors envisageable de catalyser d'autres reactions electrochimiques lentes par des electrodes modifiees par des films de polypyrrole porteurs du complexes cobalt-cyclame.
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Glenister, Alexandra. "Glucose conjugation to increase the uptake of metal complexes by cancer cells". Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/16849.
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To improve the efficacy of anticancer chemotherapy it is necessary to develop targeted treatments, which can be achieved by exploiting differences between normal and cancerous cells. The avid consumption of glucose by cancer cells compared with normal cells has been known for almost a century. The increased glucose uptake and its modified metabolism by cancerous cells, known as the Warburg effect, is recognised as a hallmark of malignant cells. A Warburg effect targeting group, rationally designed to facilitate uptake by GLUTs and be retained in cells due to phosphorylation by HK, has been synthesised. This targeting group can be conjugated to various metal complexes via an amide bond, with no deprotection reactions required after coupling, with the aim to enhance uptake and accumulation in cancer cells. The targeting vector has demonstrated inhibition of glucose phosphorylation by HK, indicating interaction with the enzyme and thereby providing the potential to facilitate an intracellular trapping mechanism for complexes it is conjugated to. Co(III)-tpa complexes have been shown to release bidentate ligands, presumably upon reduction to the more labile Co(II), in cells. To enhance delivery and uptake of anticancer agents through solid tumours a dual targeting strategy has been employed, combining Warburg effect targeting with bioreductive activation of Co(III) chaperone complexes, by conjugation of the targeting group with a tpa ligand. Uptake and distribution of the novel cancer targeted cobalt complex in cancer cell monolayers and spheroid tumour models has been investigated. Through accumulation studies, elemental mapping and fluorescent imaging the effectiveness of the Warburg effect targeting strategy has been evaluated. The novel targeting group shows promise, and distinct advantages over glucosamine, for exploiting the Warburg effect, with the targeting complex increasing delivery of a model cytotoxin to proliferating cells with enhanced glucose consumption.
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Mikros, Emmanouil. "Analyse conformationnelle en solution aqueuse de complexes d'acides aminés avec des porphyrines de cobalt (III) hydrosolubles". Paris 11, 1988. http://www.theses.fr/1988PA112219.
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A 1H NMR spectroscopic study of intramolecular interactions has been made for the octahedral complexes of cobalt (III) Co (L) (P) in water solutions. P refers to 4-N-methylpyridyl por phyrine(TMPyP) and 4carboxylphenylporphyrine(TCPP)and L to amino acid. Spectra obtained in various pH confirms the equilibrium between different complexes existing. When L contains two atoms which con bind to Co. An equilibrium also exists between different species. The stability of the complex increases with the basicity of the ligand. The conformation of the complexed aminoacids in L2CoTMPyP has been deduced from the 3J coupling constants. It was shown that for all aminoacids: a) the conformation around the N-C bond appears to be a nearly eclipsed geometry b) a staggered rotamer is predominant around Ca-Cᵝ bond. The fractional populations of the three rotamers calculated from coupling constants indicated that the rotamer capable of intramolecular interactions between the side chain and the porphyrin ring is favored as compared to the free aminoacid. Proton coordinates were calculated from the induced shifts using a Johnson-Bovey type model of ring-current. The ring of the aromatic aminoacids lies parallel to the porphyrin nucleus at a distance of ca 3. 5 Å. The free energy gain due to the hydrophobie or electrostotic interactions has been calculated (from the constant K=PI/PII+PIII of the "closed form-opened form" equilibrium) for the free and for the bound aminoacid. The order observed is: indole> phenol>benzene>phenolote>imidazole>sobutyl. Variable temperature measurement reveal that the enthalpic change contributes to the hydrophobic interaction. The electrostatic interactions were shown to contribute from a comparison between complexes with CoTMPyP and CoTCPP. Only the conformation of polar aminoacids like Asp, Asn and Ser werefound to be differentOn rapporte l'analyse conformationnelle en solution aqueuse par RMN 1H de complexes octaédriques du cobalt, de formule générale [L2CoTMPyP]5+Cl- et [L2CoTCPP] où TMPyP=tétra-N-méthylpyri dylporphyrine, TCPP=tétracarboxylphénylporphyrine et L=acide aminé. L'équilibre entre les différents complexes formés par réactions de Co(III)TMPyP avec les acides aminés a été étudié en fonction du pH. Lorsque le ligand amino acide contient deux groupements susceptibles de se lier au cobalt, il existe aussi un équilibre entre différentes espèces. La stabilité de différents complexes est d'autant plus grande que la basicité du ligand augmente. La conformation des acides aminés complexés a été déterminée à partir les constantes de couplage 3J interprotoniques. Pour tous les acides aminés il a été démontré: a) une conformation unique éclipsée autour de la liaison NCa b) une conformation décalée prédominant autour de la liaison Ca-Cᵝ. Les populations relatives de ces conformations ont été calculées à l'aide des constantes 3J. La stabilisation importante d'une conformotion dons l'acide aminé complexé par rapport à l'acide aminé libre s'explique en termes d'interactions entre la chaîne latérale et le cycle porphyrinique. La géométrie de certains complexes a été déduite à partir des déplacements chimiques induits par le cycle porphyrinique ou moyen d'un modèle empirique de type Johnson-Bovey. Le plan du noyau aromatique pour les acides aminés aromatiques est parallèle au plan du cycle porphyrine à une distance 3,5 À. Le gain d'énergie libre, dû aux interactions hydrophobes ou électrostatiques a pu être calculé (à partir des constantes d'équilibre K=PI/PII+PIII) pour l'acide aminé complexé. L'ordre de stabilisation décroissante observé est: indole>phénol>benzène>phénolate>imidazole >isobutyle. Une étude en fonction de la température montre que le terme enthalpique contribue de manière significative. Les interactions électrostatiques ont été mises en évidence dans les complexes des acides aminés avec CoTCPP. Les seuls acides aminés dont la conformation est différente dans les deux types des complexes sont les complexes avec l'Asp, l'Asn et la Ser
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Mikros, Emmanouil. "Analyse conformationnelle en solution aqueuse de complexes d'acides aminés avec des porphyrines de cobalt (III) hydrosolubles". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376165321.
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Pérollier, Céline. "Synthèse de nouvelles métalloporhyrines chirales à substituants cyclopropaniques : applications en catalyse d'époxydation asymétrique et en reconnaissance moléculaire d'enantiomères". Université Joseph Fourier (Grenoble ; 1971-2015), 1998. http://www.theses.fr/1998GRE10191.
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Le biocartol ou acide (1r)-cis-hemicaronaldehydique, un compose cyclopropanique enantiopur provenant de la synthese industrielle d'insecticides pyrethroides, est utilise comme synthon pour la preparation de nouvelles porphyrines chirales. Nous decrivons la synthese d'amides du biocartol, puis la synthese des porphyrines correspondantes par condensation avec le pyrrole. Celles-ci sont obtenues exclusivement sous la forme de l'atropoisomere , avec un rendement variant de 7 a 60%. Une serie de complexes de manganese (iii) de ces chiroporphyrines, derivees d'amides et d'esters du biocartol, ont ete prepares. Ces complexes sont de bons catalyseurs pour l'epoxydation asymetrique d'olefines prochirales. Les substrats a structure rigide cyclique sont epoxydes avec la plus grande selectivite. Ainsi, des exces enantiometriques allant jusqu'a 86% ont ete obtenus pour l'epoxydation du 1,2-dihydronaphtalene en (1s, 2r)-epoxy-1,2,3,4-tetrahydronaphtalene. L'influence de differents facteurs (nature des substituants, solvant, ligand axial, metal) sur la reactivite et l'enantioselectivite ont ete etudies. Des etudes structurales par resonance magnetique nucleaire et par diffraction des rayons x ont permis d'etablir une correlation entre structure et induction asymetrique dans cette serie. Nous avons mis en evidence que l'encombrement sterique au niveau du centre metallique lors de l'epoxydation est le determinant principal de l'enantioselectivite. Ces resultats sont interpretes par un modele geometrique de l'approche de l'olefine vers le centre metallique. La complexation d'amines derivees d'olefines prochirales par les chiroporphyrines de cobalt (iii) a egalement ete etudiee.
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Cromer, Rémy. "Porphyrines n-substituees : modelisation de l'inhibition d'hemoproteines". Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13015.
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Migration cobalt-azote des groupements : phenyl et styryl. L'etude des reactions de migration dans les porphyrines de cobalt(iii) aryliques a justifie l'utilisation de ces dernieres pour modeliser l'hydrazinolyse des hemoproteines. Les porphyrines de cobalt(iii) aryliques ont un comportement analogue a celui des porphyrines de fer(iii) aryliques. Oxydation des styryl -co(iii) porphyrines. Mecanisme de reaction. Extension de cette reaction a la cyclisation en serie arylique qui permet la synthese de la premiere porphyrine n,n'-(phenylene-1,2) analogue du produit d'inhibition suicide obtenu apres activation de l'amino-1 benzotriazole par divers enzymes a cytochrome p-450
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Darbieu, Marie-Hélène. "Complexes modeles de la methylcobalamine (meb12) : comportement de la liaison co-c en presence de derives de l'etain iv". Toulouse 3, 1987. http://www.theses.fr/1987TOU30148.
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Cartier, dit Moulin Christophe. "Structures fines d'absorption des rayons X de complexes moléculaires d'éléments de transition de la premiere période". Paris 11, 1988. http://www.theses.fr/1988PA112002.
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Ce travail est consacré à l'étude par spectroscopie d'absorption des rayons X de complexes moléculaires d'éléments de transition de la première période. Une première partie porte sur l'étude fondamentale des structures fines au seuil d'absorption : nous utilisons la flexibilité de la chimie de coordination pour étudier des complexes de stéréochimie et de structure électronique variées. Pour des molécules discrètes de structure connue, nous mettons en évidence l'influence sur le seuil du degré d'oxydation et de l'état de spin de l'élément de transition, de la symétrie du site, des distances métal-ligand et des différentes couches de voisins. Nous interprétons les transitions vers des états liés dans une approche orbitale moléculaire. Dans le domaine d'énergie où le photoélectron est éjecté, nous utilisons l'approche "diffusion multiple". L'intérêt et les limites des deux modèles sont discutés. Enfin, la présence de bandes d'intensité faible est attribuée à des transitions biélectroniques. La compréhension de l'influence des différents paramètres électroniques et structuraux qui déterminent les structures fines du seuil, et l'analyse EXAFS, sont ensuite utilisées pour l'étude structurale et stéréochimique de matériaux nouveaux intéressants pour leurs propriétés physiques, chimiques et catalytiques. Nous avons ainsi caractérisé :- les modifications structurales associées aux transitions de spin dans des complexes du fer(ll), du fer(lll) et du cobalt(ll). - la stéréochimie de complexes du titane(IV), actifs dans l'oxydation de sulfures en sulfoxydes : à toutes les étapes de la réaction, les espèces sont octaédriques et ne présentent pas d'arrangement di -oxo. - l'ordre local dans les porphyrines de fer à anse de panier, modèles de l'hémoglobine. Le spectre de la forme oxygénée permet de proposer une formulation Fe(ll)-02 plutôt que Fe(lll)-02 -. L'EXAFS résolu dans le temps permet de réaliser des cinétiques structurales et a été utilisé pour étudier l'environnement de l'ion fer au cours de la réaction d'oxydation d'une porphyrine de fer(ll) à anse de panierLn this work, molecular complexes of the first period transition elements are studied by X-ray absorption spectroscopy. The first point is devoted to a fundamental study of the absorption edge: we take advantage of the versatility of coordination chemistry, to study complexes, with different stereochemistries and electronic structures. Ln the case of isolated molecules with well-known structures, we point out the influence of oxidation and spin states of the metallic ion, symmetry, metal-ligand distances and remote neighbours shells upon the edge. We discuss the transitions towards bound states using a molecular orbital approach. As for the XANES part of the spectrum, we use multiple scattering theory. We discuss the interest and the limitations of the two models. Sorne weak bands can be attributed to bielectronic transitions. This knowledge of the influence of different structural and electronic parameters which impel the fine structures of the edge and EXAFS spectroscopy are then used to characterise the local structure and stereochemistry of new compounds, of interest for their physical, chemical and catalytic properties. Then we studied:- The structural changes occurring during thermal spin cross-over in iron(ll), iron(lll) and cobalt(ll) complexes. - The stereochemistry of titanium(IV) complexes active in oxidation of sulfides in sulfoxides :at each reaction step, species are octahedral and do not show di µ oxo geometry. - The local order in basket-handle iron porphyrins, model compounds of haemoglobin. The spectrum of the oxy species allows to propose a Fe(ll)-02 formulation rather than a Fe(lll)-02 -. We used the time resolved EXAFS spectrometer at LURE to record structural kinetics data and study iron surroundings during the oxidation of an iron(ll) basket-handle porphyrin
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Le, Mest Yves. "Etude des propriétés électrochimiques de biporphyrines de type "face-à-face" : réactivité des dérives du cobalt vis-à-vis de l'oxygène". Brest, 1988. http://www.theses.fr/1988BRES2013.
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Brazi, Eric. "Activation de la liaison C-H hydroxylation catalytique des hydrocarbures par de nouveaux complexes alkylperoxydiques de cobalt (III), désydrogénation sélective et catalytique de cycloalcanes... /". Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37603426w.
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Kim, Chung Sik. "Corrole Synthesis and Catalytic Applications Toward Cobalt(III)-Catalyzed Epoxidation, N-H Insertion, and Cyclopropanation". Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3459.
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A variety of bromocorroles, useful precusors for Pd-based cross coupling, were sucessfully synthesized in moderate to good yields. Chiral corroles were also synthesized through use of chiral amides in the aforementioned cross coupling reactions. Cobalt complexes bearing π-acceptor (CNtBu) and σ-donor (PPh3) ligands were also prepared in excellent yields. In this dissertation, cobalt (III) corrole complexes were applied to three different reaction areas: epoxidation, N-H insertion, and cyclopropanation. Cobalt(III) corroles were found to be efficient catalysts for epoxidation reactions. The epoxidation reactions can be carried out using ethyl phenyldiazoacetate, an acceptor/donor diazo compound, as a carbenoid precusor.The reaction provided highly diastereoselective epoxides. In addition to epoxidation, N-H insertion reactions using cobalt(III) corroles as catalysts smoothly produced the desired products with diverse diazo reagents. The reactions were screened using ethyl phenyldiazoacetate with a selection of anilines and amides. In order to investigate non-ylide intermediate based metal-mediated catalytic reactions, cyclopropanation was conducted using cobalt (III) corroles as catalysts, producing the desired cyclopropyl nitroesters in high yields and with excellent diastereoselectivity under a concerted mechanism. Asymmetric cyclopropanation reactions were carried out using chiral cobalt(III) corrole complexes to generate the enatiomerically pure desired cyclopropanes in moderate yields.
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Billaud, Claude. "Polymerisation de monomeres vinyliques amorcees par excitation a grande longueur d'onde du complexe azidopentaammine de cobalt (iii)". Clermont-Ferrand 2, 1999. http://www.theses.fr/1999CLF22171.
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Les reactions d'homopolymerisation et de copolymerisation de la n-vinylpyrrolidone (nvp) et du methacrylate de 2-hydroxyethyle (hema) photoamorcees par le complexe co(nh 3) 5n 3 2 + ont ete etudiees en solution aqueuse. Ce complexe de cobalt (iii) conduit a un processus de photo-oxydoreduction (formation de cobalt (ii) et du radical azide) sous excitation dans sa bande de transfert de charge (365 nm). Nous avons montre que cette reaction se produit egalement lors d'excitation dans sa bande due au champ des ligands (546 et 633 nm). En utilisant co(nh 3) 5n 3 2 +, nous avons pu realiser des reactions de polymerisation amorcees par le radical azide sous excitation de faible energie (jusqu'a 633 nm). Lors de l'etude cinetique de la reaction d'homopolymerisation de nvp sous excitation a 365 et 546 nm, l'etude de l'influence des differents parametres cinetiques (concentration en amorceur et en monomere, intensite lumineuse absorbee) sur la vitesse de polymerisation et la masse molaire a permis de mettre en evidence l'intervention de deux modes de terminaison differents : a faible concentration en amorceur, la terminaison se produit principalement par combinaison de macroradicaux tandis qu'a plus forte concentration, les macroradicaux reagissent avec le complexe de cobalt (iii) a l'etat fondamental selon un processus de terminaison oxydante. Dans le cas de hema, seule la terminaison par combinaison intervient ; le poly(methacrylate de 2-hydroxyethyle) etant insoluble dans l'eau, l'etude cinetique de la polymerisation de hema a ete realisee dans un melange h 2o/ch 3cn (70/30). Pour completer cette etude, nous avons determine les constantes de vitesse des reactions d'amorcage par radiolyse pulsee. Cette reaction est cent fois plus efficace avec nvp qu'avec hema. Les mecanismes et les possibilites de synthese de copolymeres hema/nvp par voie photochimique (365 nm) ont ete etudies. Nous avons mis en evidence par rmn la formation de copolymeres riches en hema et hydrosolubles.
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Soibinet, Mathieu. "Complexes du cuivre (II), nickel (II) et cobalt (III) avec des ligands bis macrocycliques dérivés du cyclam et du cyclen : Synthèse, études thermodynamique et structurale". Reims, 2002. http://www.theses.fr/2002REIMS023.
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Des ligands bis-macrocycliques dérivés du cyclam ou du cyclen ont été obtenus par une nouvelle méthode de synthèse via un intermédiaire bis-cis-aminal. L'étude des propriétés thermodynamiques et structurales des complexes formés entre ces ligands et les cations cuivre(II), nickel(II) et cobalt(III) a été réalisée. En solution aqueuse, l'étude potentiométrique et spectroscopique (RPE, UV visible) des complexes du cuivre(II) a montré l'existence, selon la valeur du rapport R = [ligand]/[métal], de complexes mononucléaires ou dinucléaires de très grande stabilité. A l'état solide, les complexes dinucléaires obtenus ont été essentiellement étudiés par diffraction de rayons X et par différentes méthodes spectroscopiques (absorption X, UV visible, RPE, RMN). Des essais de complexation d'anions ont été réalisés. Seul le complexe dinucléaire Cu2-paracyclen permet d'obtenir la fixation d'anions, tels que les ions oxalate, malonate ou hexacyanoferrate(II) entre les deux centres métalliques.
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Brazi, Eric. "Activation de la liaison C-H : hydroxylation catalytique des hydrocarbures par de nouveaux complexes alkylperoxydiques de cobalt (iii), déshydrogénation sélective et catalytique de cycloalcanes en présence d'éponges à hydrogènes à base d'uranium métal". Paris 6, 1987. http://www.theses.fr/1987PA066680.
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Mirjana, Radanović. "Kompleksi nekih prelaznih metala sa Šifovim bazama aminogvanidina". Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2015. https://www.cris.uns.ac.rs/record.jsf?recordId=95548&source=NDLTD&language=en.
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U ovoj doktorskoj disertaciji opisane su sinteze novih kompleksa prelaznih metala sa piridoksiliden- (PLAG), odnosno saliciliden-aminogvanidinom (SALAG). Dobijenikompleksi su okarakterisani elementalnom analizom, IR spektrima, konduktometrijskim i magnetnim merenjima, a većina i rendgenskomstrukturnom analizom. Osim toga, dobijene su i nove forme ovih Šifovih baza, i to u vidu monokristala, čime su omogućena ispitivanja njihovih molekulskih i kristalnih struktura, kao i uporedna analiza sa koordinovanim ligandima. Sa PLAG je sintetisano 7 novi kompleksa Cu(II), a pored toga po prvi put suizolovani mono i bis(ligand) kompleksi Fe(III) i Co(III), mono(ligand) kompleksi V(V), kao i jedan kompleks Zn(II) u kojem ovaj potencijalno tridentatni ONN ligand, umonoprotonovanoj formi, ima ulogu kontra-jona. Sa stanovišta geometrije zajedničko za izolovane komplekse Cu(II) i V(V) je da imaju kvadratno-piramidalnu strukturu, sa izuzetkom jednog kvadratno-planarnog kompleksa Cu(II), dok je u kompleksima Fe(III) i Co(III) nađeno očekivano oktaedarsko okruženje centralnogjona. Pored ovih, sintetisano je i pet novih kompleksa sa SALAG, od kojih su dvakompleksa Cu(II) i kompleks V(V) okarakterisani rendgenskom strukturnomanalizom, dok je mikrokristalnim bis(ligand) kompleksima Co(III) i Ni(III) na osnovufizičko-hemijskih karakteristika predložena odgovarajuća struktura. Zajedničko za obe opisane Šifove baze je da se koordinuju na ONN tridentatni način, i to preko atoma kiseonika deprotonovane fenolne grupe i atoma azota azometinske i imino grupe AG fragmeta. Posebno je naglašeno da su saPLAG izolovana dva dimerna kompleksa Cu(II) u kojima je po prvi put nađena tetradentatna koordinacija ovog liganda, u koju je dodatno uključen atom kiseonika hidroksimetil-grupe PL-ostatka. Za razliku od SALAG, koji je u izolovanim kompleksima koordinovan isključivo kao monoanjon, nastao deprotonacijom fenolneOH-grupe, za PLAG je osim ove, potvđena koordinacija u neutralnoj, zwitter-jonskoj, ali i dvostruko deprotonovanoj formi. Zwitter-jonska forma liganda nastaje migracijom atoma vodonika sa fenolnog hidroksila na piridinski atom azota PL-ostatka, dok deprotonacijom piridinskog ili hidrazinskog atoma azota, odnosno oba pomenuta atoma nastaju monoanjon i dianjon helatnog liganda, respektivno. Na kraju, urađena su i ispitivanja antimikrobne aktivnosti odabranih jedinjenjaprema predstavnicima grampozitivnih i gramnegativnih bakterija, kao i dve kulturekvasca. Tom prilikom nije utvrđena nikakva inhibitorna aktivnost prema primenjenimbakterijskim sojevima, dok su u slučaju kvasaca izvesno mikrobicidno dejstvo pokazali samo kompleksi Cu(II).This PhD thesis describes the syntheses of some new transition metal complexes with pyridoxilidene- (PLAG) and salicylideneaminoguanidine (SALAG). Obtained complexes are characterized by elemental analysis, IR spectroscopy, conductometric and magnetic measurements. Besides, the structural analysis of majority of the obtained complexes was performed. Some new forms of these Schiff bases are synthesized in form of single crystals, which made their X-ray analysis as well as comparison with coordinated forms possible.With PLAG, 7 new Cu(II) complexes were obtained and for the first time mono and bis(ligand) complexes of Fe(III) and Co(III) as well mono(ligand) complexes of V(V) were isolated. Furthermore, the structure of Zn(II) complex in which PLAG in its monocationic form has a role of counter ion is presented. With the exception of one Cu(II) complex, all reported Cu(II) and V(V) complexes have a square-pyramidal geometry, whilst Fe(III) and Co(III) are situated in octahedral surroundings. Also, five new complexes of Cu(II), Co(III), Ni(II) and V(V) with SALAG were synthesized. In both Cu(II) complexes and V(V) complex the expected coordination mode and geometry were confirmed by X-ray analysis, while octahedral structure of bis(ligand) complexes with Co(III) and Ni(II) was proposed based on results of physico-chemical characterization.Both PLAG and SALAG coordinate the metal ion in tridentate ONN manner, through the oxygen atom of deprotonated phenolic group and nitrogen atoms of azomethine and imino groups of AG moiety. It is also emphasized that in two dimeric Cu(II) complexes with PLAG tetradentate coordination mode was found, in which the oxygen atom of hydroxymethyl group of PL residue was additionally involved. Unlike SALAG, which is coordinated as monoanion in all of the examined complexes, PLAG can have one of three degrees of deprotonation. Zwitter-ion of PLAG is formed by migration of H-atom from phenolic oxygen to pyridine nitrogen, while the deprotonation of pyridine or/and hydrazine nitrogen, makes it mono-and dianion, respectively.Also, microbiological tests on the selected compounds were preformed. Namely, antimicrobial activity of these compounds against some gram-positive and gram-negative bacteria, as well as some yeast cultures was examined and none of the samples showed antimicrobial activity against bacteria, whilst only Cu(II) complexes showed certain inhibitory effect against yeasts.
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Önem-Siakou, Evgenia. "Cobalt(III)-Kohlenhydrat-Verbindungen". Diss., lmu, 2003. http://nbn-resolving.de/urn:nbn:de:bvb:19-33130.
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Xavier, Fernando Roberto. "Novos complexos binucleares não-simétricos de ferro (III) cobalto(II) e de gálio(III) cobalto(II) como modelos miméticos para as fosfatases ácidas púrpuras metalo-substituídas". Florianópolis, SC, 2006. http://repositorio.ufsc.br/xmlui/handle/123456789/89225.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em Química.Made available in DSpace on 2012-10-22T18:16:43Z (GMT). No. of bitstreams: 1 230074.pdf: 2278286 bytes, checksum: 566304e98f55e0e1a2b3ede6927d6cf0 (MD5)
A natureza aprendeu a utilizar propriedades especiais dos metais para realizar uma ampla variedade de funções associadas aos sistemas vivos. Metaloproteínas que realizam funções catalíticas são denominadas de metaloenzimas, constituindo então uma classe especial de compostos bioinorgânicos. Neste contexto, as fosfatases ácidas púrpuras (PAPs), metaloenzimas pertencentes à classe das hidrolases, catalisam a hidrólise de ésteres e anidridos do ácido fosfórico em uma faixa de pH de 4 a 7. A característica cor púrpura dessa subclasse de fosfatases ácidas é resultado de um de transferência de carga do tipo ligante metal (OTyr?FeIII) em torno de 560 nm. Os complexos modelos tiveram papel fundamental no entendimento das propriedades físicos-químicas das PAPs, antes da resolução das estruturas cristalinas das mesmas. Assim, através do estudo estrutural, espectroscópico e de testes de reatividade, busca-se esclarecer o mecanismo através do qual ocorre o processo catalítico em complexos modelos para que estes possam auxiliar na elucidação do mecanismo pelo qual a enzima nativa atua. Neste trabalho foram sintetizados e caracterizados por análise elementar de CHN; medidas de condutividade; espectroscopias no infravermelho, eletrônica e Mössbauer; eletroquímica e titulação potenciométrica dois novos complexos de ferro(III)cobalto(II) e gálio(III)cobalto(II) empregando-se o ligante H2BPBPMP76, já descrito na literatura. Os complexos 1 - [FeIIICoII(BPBPMP)(µ-OAc)2]ClO4 . 0,25 H2O e 2 - [GaIIICoII(BPBPMP)(µ-OAc)2]ClO4 . H2O tiveram suas estruturas cristalinas resolvidas apresentando-se isoestruturais entre si, sendo ainda apontados como modelos estruturais para as PAPs metalo-substituídas, pois mimetizam os resíduos de aminoácidos presentes no sítio ativo das PAPs e simulam a distância intermetálica presente nas mesmas. Os estudos realizados frente à hidrólise do substrato modelo 2,4-bisdinitrofenilfosfato (2,4-BDNPP) resultaram em fatores de aceleração de 19,2 e 21,2 mil vezes, espectivamente, em relação à reação não catalisada sendo o complexo 2 (GaIIICoII) o que se apresentou mais efetivo na conversão do substrato a produtos. Estudos inibitórios (por íons OAc- e HPO4 2-) para a reação do 2,4-BDNPP mostraram que os íons acetato à baixas concentrações não influenciam significativamente o processo catalítico, porém, íons fosfato devido a sua alta constante de associação podem comprometer a catálise mesmo em concentrações reduzidas. A partir dos dados estruturais, espectroscópicos, eletroquímicos, cinéticos e de titulação potenciométrica foi possível propor um ciclo catalítico para a hidrólise do 2,4-BDNPP, mediada pelos complexos 1 e 2 compatível com outros já descritos na literatura.
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Barbusse, Danielle. "Contribution à la caractérisation des matériaux : étude des couches minces, multicouches et superréseaux III-V et II-VI par double diffraction des rayons X (composition, qualité, contraintes) : étude structurale par absorption X au seuil K d'une série de complexes du cobalt et du fer, XANES et EXAFS de laboratoire". Montpellier 2, 1991. http://www.theses.fr/1991MON20189.
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Un dispositif experimental de double diffraction des rayons x a ete concu et realise au laboratoire. Des mesures de desaccords de maille inferieurs a 5. 10##3 sont accessibles. Dans la premiere partie, des etudes qualitatives (qualite cristalline) et quantitatives (composition, contraintes) ont ete effectuees sur des couches minces multicouches et superreseaux de semiconducteurs. La deuxieme partie montre la faisabilite d'une mesure d'absorption x au laboratoire. La fiabilite des resultats obtenus est demontree a partir de l'etude xanes et exafs au seuil k du fer et du cobalt dans quelques complexes
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Guindy, Christina Irene. "Cobalt complexes of radical ligands". Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408058.
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Ghaschghaie, Natascha. "Heteroleptische Cobalt(III)-Chelatkomplexe mit Bioliganden". Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-121266.
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Medforth, C. J. "Cobalt (III) porphyrin N.M.R. shift reagents". Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384368.
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Beaumont, Ian R. "The chemistry of cyclopentadienyl cobalt complexes". Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291970.
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Doerrer, Linda H. (Linda Helen) 1968. "Cobalt, zinc, and cadminum tropocoronand complexes". Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43296.
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Gilby, Liam Michael. "Polynuclear cobalt complexes of 2-pyridones". Thesis, University of Edinburgh, 1994. http://hdl.handle.net/1842/13899.
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The synthesis, structure and physical properties of several novel multinuclear cobalt complexes of substituted 2-pyridones are reported. Reaction of cobalt(II) salts and the anion of 6-chloro-2-pyridone results in the formation of a trinuclear structure which has been characterised by X-ray crystallography and contains a linear array of the three metals. With the 6-methyl derivative of 2-pyridone, two compounds were isolated, a heterobimetallic polymer of cobalt and sodium in which the metal centres are bridged by chelating pyridone ligands and a mononuclear complex containing two chelating ligands. Both have been characterised by X-ray crystallography. A range of similar complexes are synthesised of formula Co(xhp)2L2, xhp = mhp, chp, fhp and hp and L2 = 2,2'-bipyridyl, 4,4'-dimethyl-2,2'-bipyridyl or 1,10-phenanthroline. The synthesis of a dinuclear complex of 6-bromo-2-pyridone is reported and characterised by X-ray crystallography. Magnetic studies on this compound show an antiferromagnetic coupling between the two metals at low temperature. The physical properties of these compounds have been studied and the results are discussed. The studies include, NMR spectroscopy, electrochemistry and magnetic measurements. The synthesis and structure of a novel two-dimensional polymer containing cobalt and sodium bridged by acetate ligands is reported along with the attempted syntheses of mixed metal complexes containing cobalt and a lanthanoid from trinuclear cobalt complexes. Detailed descriptions of all structurally characterised compounds are given with regard to the metal environments, arrangements of ligands and packing motifs. Comparisons of these new structures with known copper complexes are made.
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Ullman, Andrew. "Polynuclear Cobalt Complexes as Models of a Cobalt Water Oxidation Catalyst". Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:23845429.
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The electrochemical oxidation of Co2+ ions in the presence of a buffering species such as phosphate (Pi), methyl phosphonate (MePi), and borate (Bi) leads to the formation of amorphous cobalt oxide thin films that are capable of catalyzing the four electron-four proton oxidation of water to dioxygen. These cobalt oxygen evolving catalysts (Co–OECs) have been extensively studied by electrochemical techniques; however, the amorphous nature of these films means that garnering insights at the molecular and atomic level is difficult because electronic and structural characterization methods rely on measurements of bulk material. To address this challenge, polynuclear cobalt hydroxide and cobalt oxide compounds have been employed as platforms for understanding Co–OECs at the molecular level.
In the first part of the thesis, we present the synthesis of a heptanuclear cobalt cluster in two different oxidation states, Co(II)7 and a mixed valence Co(III)Co(II)6. An anomalously slow self–exchange electron transfer rate as compared to that predicted from semiclassical Marcus theory was measured, supporting a charge transfer process that is accelerated by dissociation of the anion from the oxidized cluster. This mechanism sheds light on the inverse dependence of anions in the deposition mechanism of Co–OECs. Moreover, the results address a long-standing controversy surrounding the Co2+/3+ self–exchange electron transfer reaction of the hexaaqua complex.
In the second part of the thesis, we report the synthesis and characterization of a dinuclear cobalt complex, which we use as an edge sites mimic (ESM) of the Co-OEC. A comparative investigation of the Pi and Bi binding of buffers to this ESM is provided. We find that the binding to the boric acid component of borate buffer is rapid, while binding to K2HPO4 is much slower, taking days to equilibrate at room temperature. These studies are used to provide a model for the interaction of Pi and Bi species with the active site of the Co-OEC. An inverse dependence on [Bi] of the electrochemical driven water oxidation activity by Co-OECs is demonstrated, which provides validation for the model and indicates that dinuclear cobalt edge sites are necessary for water oxidation catalysis.
In the final chapter of the thesis, we use a series of spectroscopic and electrochemical methods to show that the observed water oxidation activity of the compound class Co4O4(OAc)4(py–X)4 emanates from a Co(II) impurity. This impurity is oxidized to produce Co-OEC, which is an active water oxidation catalyst. Differential electrochemical mass spectrometry (DEMS) is used to characterize the fate of glassy carbon at water oxidizing potentials, and demonstrate that such electrode materials should be used with caution for the study of water oxidation catalysis. We then investigate the electrochemical properties of Co4O4 cubanes in non-aqueous solvents, showing that the neutral cubanes may be oxidized by two electrons yielding a formal oxidation state of Co(IV)2Co(III)2. Finally, we show that these cubanes may be synthetically modified with tethered NMI photooxidants, which opens new avenues for exploring fixed-distance photoinduced ET using Co4O4 cubanes as the electron donor. Ultra-fast transient absorption experiments demonstrate that a charge separated state is formed following laser excitation.Chemistry and Chemical Biology
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Powell, A. K. "Iron(III) carboxylato complexes". Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356434.
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Chen, Ming-Chou. "Metallacyclobutenes as reactive intermediates : conversion to cobalt diene and cobalt allene complexes /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1998. http://wwwlib.umi.com/cr/ucsd/fullcit?p9834967.
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Ghaschghaie, Natascha [Verfasser]. "Heteroleptische Cobalt(III)-Chelatkomplexe mit Bioliganden / Natascha Ghaschghaie". München : Verlag Dr. Hut, 2010. http://d-nb.info/1008341770/34.
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Lau, S. "Cobalt(III) acetate - its structures and catalytic activity". Thesis, University of Hull, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233969.
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Freeman, Jonathan D. "Cobalt(II) complexes and carbon dioxide fixation". Thesis, University of York, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341473.
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Bramham, George. "Synthesis and structures of cobalt boryl complexes". Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424001.
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O'Neill, Edward. "Cobalt complexes as responsive MRI contrast agents". Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17854.
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Responsive magnetic resonance imaging (MRI) contrast agents are capable of responding to the chemical environment by altering the paramagnetism of the metal centre. The most common metal centre used is gadolinium, which has toxicity concerns and exerts residual paramagnetism in its off state. Since accumulation of gadolinium complexes in their off state can provide a false positive in the observed relaxation rate of water molecules, fully diamagnetic cobalt(III) and the reductive switch to cobalt(II) is presented in this thesis as a potential solution. A number of cobalt ligand scaffolds were investigated for their ability to act as off-to-on MRI probes in response to a reducing chemical environment that would be present in tissue hypoxia. A series of TPA derivatives with varying charge was synthesised, and accumulation and activation of complexes within tumour spheroids were investigated using a combination of inductively coupled plasma mass spectrometry (ICP-MS), MRI and nuclear magnetic resonance (NMR) spectroscopy techniques. One complex, Co-TPA3, showed selective uptake in the quiescent non-proliferating hypoxic regions of the tumour spheroid and activation to Co(II)TPA3 could be detected by MRI. Speciation and stability could also be determined by paramagnetic 1H NMR, and Co-TPA3 could be a suitable candidate for future MRI hypoxia imaging, as well as a scaffold for theranostic applications. The paramagnetic 1H NMR signals of another cobalt complex, CoMe6TrenCl were investigated in the presence of various anions in solution. Unique 1H NMR signals were observed for each anion tested even in complex solutions and the binding affinities of anions and relaxation parameters of the paramagnetic signals were characterised by a variety of NMR spectroscopic techniques.
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Riga, Rocha Beatriz Aline. "Síntese de ligantes diimínicos para obtenção de complexos organocobalto(III) para polimerização radicalar mediada por cobalto /". São José do Rio Preto, 2017. http://hdl.handle.net/11449/149815.
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Orientador: Beatriz Eleutério GoiBanca: Giovana Gioppo Nunes
Banca: Sérgio Antônio Marques de Lima
Resumo: Neste trabalho objetivou-se a síntese e caracterização de oito complexos de cobalto(II) que fossem aptos a atuarem como agentes controladores na Polimerização Radicalar Mediada por Cobalto do monômero acetato de vinila. Através da modulação da esfera de coordenação destes complexos com a alteração dos efeitos estéricos e eletrônicos promovidos pela coordenação de ligantes α-diiminas, buscou-se estabelecer parâmetros para propor a forma como estes complexos mediam a CMRP do referido monômero. Os complexos foram divididos em dois grupos, objetivando uma avaliação mais eficiente da forma como os efeitos estéricos e eletrônicos interferem na capacidade controladora dos mesmos. Após a variação sistemática das proporções molares entre complexo, iniciador e monômero encontrou-se na proporção [Co]/[AIBN]/[VAc] = 1/3,25/542 os resultados mais satisfatórios deste trabalho. O uso de DMSO fora prejudicial para os complexos 2a-c, porém fez com que os complexos 2d-h apresentassem melhorias, reduzindo seus valores de polidispersidade e aumentando as massas moleculares dos polímeros. O complexo 2b fora escolhido como o melhor controlador do grupo do efeito estérico, por reunir em si as características estérias e eletrônicas que o fizeram apresentar os menores valores de polidispersidade (Đmáx = 1,43). Com relação ao grupo de complexos do efeito eletrônico, fora o complexo 2f que, devido à maior estabilidade estrutural conferida ao complexo por seu substituinte cicloexil,...
Abstract: This work aimed the synthesis and characterization of eight cobalt(II) complexes which could be able to act as controlling agents in vinyl acetate radical polymerization mediated by cobalt. By modulating the coordination sphere of these complexes, modifying the steric and electronic effects offered by the α-diimine ligands, we sought to establish parameters to propose how these complexes mediate the CMRP of vinyl acetate. The complexes were split in two groups in way to assess efficiently how the electronic and steric effects can affect the controlling capacity of the CoII(α-diimine).A systematic variation of the molar ratio such as [Co]/[initiator] and [Co]/[monomer] made it possible to choose [Co]/[initiator]/[monomer] = 1/3.25/542 as the ratio that provided certain level of control. The addition of DMSO was detrimental to the complexes 2a-c, but caused an improvement to the activity of complexes 2dh, reducing their polydispersity values and increasing the molecular weights of the polymers. Complex 2b was chosen as the best controller of the steric effect group, its steric and electronic characteristics made possible to reach the lowest polydispersity of its group (Đmax = 1.43).Regarding to the group of complexes of the electronic effect, it was the complex 2f that had the smallest polydispersity of its group, between 1.12 and 1.58, due to the greater structural stability conferred to the complex by its cyclohexyl substituent
Mestre
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Leznoff, Daniel Bernard. "Paramagnetic organometallic complexes of chromium, iron and cobalt". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25093.pdf.
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Dinh-nguyen, Minh-thu. "Complexes cobalt-oxime pour la production d'hydrogène électrolytique". Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00709175.
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L'économie actuelle repose sur l'utilisation d'énergies fossiles dont les réserves sont limitées. En plus, l'utilisation de ces ressources a un impact négatif sur l'environnement dû à l'émission des gaz polluants et du CO2. Il est donc nécessaire de remplacer les ressources fossiles par les énergies renouvelables. Les énergies renouvelables peuvent être facilement converties en électricité pour une utilisation directe, mais l'électricité ne peut pas être stockée en grande quantité. Dans ce contexte, l'hydrogène pourrait servir de vecteur énergétique. Il est possible de produire de l'hydrogène par électrolyse de l'eau. L'hydrogène sera ensuite utilisé via une pile à combustible pour fournir de l'électricité et de la chaleur. Ce procédé ne produit que de l'eau qui va être re-consommé ensuite par l'électrolyse.Ce travail de thèse est axé sur la production d'hydrogène par électrolyse de l'eau en milieu acide par la technologie PEM (proton exchange membrane). L'objectif est de remplacer le platine, catalyseur de la réduction à la cathode par des complexes de cobalt de type cobalt-oxime.Le premier chapitre traite différents aspects de l'électrolyse de l'eau et différents catalyseurs étudiés dans la littérature.Le second chapitre décrit différentes techniques expérimentales utilisées pour caractériser les complexes étudiés.Le chapitre trois décrit la synthèse et l'activité catalytique des complexes de cobalt-oxime en solution dans l'acétonitrile vis-à-vis de la réduction des protons en hydrogène.Le chapitre quatre présente les premiers travaux obtenus en utilisant les complexes de cobalt-oxime à la place du platine dans les électrolyseurs PEM.
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Dicks, James Paul. "Dithiolene complexes of ηâµ-cyclopentadienyl cobalt centres". Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422748.
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Nicholls, Julian Charles. "Carbon-carbon bond cleavage in agostic cobalt complexes". Thesis, University of Salford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258557.
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