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1
Silver, Sunshine Christine. "Kinetic, mechanistic and spectroscopic studies of spore photoproduct lyase". Diss., Montana State University, 2010. http://etd.lib.montana.edu/etd/2010/silver/SilverS1210.pdf.
Testo completoAbstract (sommario):
Spore forming organisms are a health threat to humans and other animals in part due to a remarkable resistance to UV irradiation. This resistance results from two events: first, the formation of a unique thymine dimer, 5-thyminyl-5,6-dihydrothymine (spore photoproduct, or SP) upon UV irradiation; and more importantly, the rapid and specific repair of this DNA photoproduct to two thymines by spore photoproduct lyase (SP lyase). Understanding the molecular basis of this radical-mediated DNA repair will ultimately allow for a better understanding of how to address the health risks caused by spore forming bacteria. SP lyase requires S-adenosyl-L-methionine and a [4Fe-4S]¹+/²+ cluster to perform its catalysis. Presented in this work is a characterization of Clostridium acetobutylicm SP lyase and its ability to repair stereochemically defined dinucleoside and dinucleotide synthetic substrates. Careful synthesis and characterization followed by assays monitored by HPLC indicate SP lyase repairs only the 5R isomer of SP with an activity of 0.4 nmol/min/mg (dinucleoside substrate) and 7.1 nmol/min/mg (dinucleotide substrate). These results support the longstanding theory of SP formation by dimerization of adjacent thymines in double-helical DNA. Kinetic and mechanistic studies were pursued to further elucidate the mechanism of SP repair. Upon pre-reducing SP lyase, the specific activity increased nearly 4-fold to 1.29 μmol/min/mg. Mechanistic studies utilizing [C-6-³H] SP DNA as the substrate revealed a primary tritium kinetic isotope effect of 16.1, indicating a rate determining step during the repair reaction. These results suggest nonstereospecific SP formation regarding the C-6 position and subsequent stereospecific abstraction of the C-6 H atom by SP lyase. Mossbauer and Fe/S K-edge X-ray absorption studies of anaerobically prepared SP lyase aided in further characterization of the [4Fe-4S] cluster and its interaction with SAM. The Fe K-edge EXAFS provide evidence for a slight cluster distortion upon interacting with SAM as a new spectral feature indicative of longer Fe-Fe distances is observed. The Fe K-edge XANES provide further support that SAM is not undergoing reductive cleavage in the presence of reduced SP lyase. Our XAS studies may provide new insights into the mechanism by which radical SAM enzymes initiate their diverse catalysis.
'Co-authored by Tilak Chandra, Egidijus Zilinskas, Eric M. Shepard, William E. Broderick, Joan B. Broderick, Shourjo Ghose, Jeffrey M. Buis, David J. Gardenghi, BoiHanh Huynh, and Robert K. Szilagyi.'
2
Gómez, Martín Juan Carlos. "Spectroscopic, kinetic and mechanistic studies of atmospherically relevant I2-O3 photochemistry". Berlin Logos-Verl, 2006. http://deposit.d-nb.de/cgi-bin/dokserv?id=2927252&prov=M&dok_var=1&dok_ext=htm.
Testo completo
3
Gómez, Martín Juan Carlos. "Spectroscopic, kinetic and mechanistic studies of atmospherically relevant I2/O3 photochemistry /". Berlin : Logos-Verl, 2007. http://deposit.d-nb.de/cgi-bin/dokserv?id=2927252&prov=M&dok_var=1&dok_ext=htm.
Testo completo
4
Whyte, Lynden J. "A kinetic and mechanistic study of tropospheric reactions". Thesis, University of East Anglia, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314391.
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5
El-Agez, Bassam Ali. "A kinetic and spectroscopic study on cytochrome c oxidase". Thesis, University of Essex, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305116.
Testo completo
6
Kalinga, Shivashankar. "Peroxynitrite-induced modifications of myoglobin : a kinetic and mechanistic study /". Zürich : ETH, 2005. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16014.
Testo completo
7
Siu, Tung. "Kinetic and mechanistic study of aqueous sulfide-sulfite-thiosulfate system". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0007/MQ45585.pdf.
Testo completo
8
Scott, Laura-Marie. "Kinetic and mechanistic study of Lilestralis, a synthetic muguet fragrance molecule". Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=165414.
Testo completoAbstract (sommario):
In the multi-step synthesis of Lilestralis, a synthetic muguet fragrance, the kinetics and mechanism of the formation of 3-(3-t-butylphenyl)-2-methylpropan-1-ol (m-LOL) and 4-(3-t-butylphenyl)-2-methylpropan-1-ol (p-LOL) from 2-methyl-3-phenylpropan-1-ol (MPP) and isobutylene using concentrated liquid phosphoric acid as a catalyst was investigated. By-products that include phosphate esters of MPP, m-LOL and p-LOL and oligomers of isobutylene were produced during this reaction and their role within the kinetics and mechanism was also investigated. When crystalline phosphoric acid is dissolved in water, it can form equilibrium polyphosphate mixtures at high acid concentrations. The phosphate species have the general formula Hn+2PnO3n+1 and consist of species such as orthophosphoric acid (H3PO4), pyrophosphoric acid (H4P2O7) and triphosphoric acid (H5P3010). The presence of polyphosphate within liquid phosphoric acid solutions used in this study was investigated using 31P NMR. To investigate the influence of water on the reaction, a number of experiments were performed using 1,4-dioxane as a solvent. This was chosen as the boiling points and density are similar to water, although it is classified as an aprotic solvent. Phosphate esters of MPP, m-LOL and p-LOL are produced as by-products and can potentially undergo hydrolysis when water is present, therefore reactions using aqueous phosphoric acid solutions may not give a true reflection of the concentration of phosphate esters produced. The use of heterogeneous catalysts was also investigated in order to improve yield and selectivity for p-LOL and m-LOL. These include acid catalysts such as solid phosphoric acid supported on Kieselguhr (SPA), sulphated zirconia and ultra stable zeolite-Y (H-USY).
9
Souza, Valdir Araujo de. "Corrosion and erosion-corrosion of wc-based cermet coatings - a kinetic and mechanistic study". Thesis, Heriot-Watt University, 2004. http://hdl.handle.net/10399/318.
Testo completo
10
Fakih, Mariam. "Réactivité atmosphérique des principaux produits d'oxydation de première génération des monoterpènes". Electronic Thesis or Diss., Reims, 2024. http://www.theses.fr/2024REIMS010.
Testo completoAbstract (sommario):
Les monoterpènes sont des composés organiques volatils biogéniques (COVB) largement émis dans l'atmosphère par les forêts et les cultures végétales, représentant ainsi des acteurs significatifs de la chimie atmosphérique. Leur réactivité importante envers les oxydants atmosphériques a fait sujet de plusieurs études dans la littérature. Cependant, leurs produits de première génération d’oxydation sont moins évalués et pourraient expliquer en partie la réactivité manquante ainsi que la sous-estimation de la formation des AOS par les modèles. Dans ce contexte, cette étude vise à comprendre la réactivité atmosphérique de cinq COVB (nopinone, myrténal, kétolimonène, caronaldéhyde, et limononaldéhyde) qui sont des produits de première génération de l’oxydation des α et β-pinène et du limonène. Ce travail porte sur l’étude des processus de dégradation en déterminant la cinétique et le mécanisme des réactions d'oxydation des COVB visés par le radical OH, le chlore et l’ozone, ainsi que leur potentielle de photolyse au travers de l’étude de leurs spectres d’absorption UV-Vis. Pour ce faire, les réactions d'oxydation des cinq produits de première génération d’oxydation de monoterpènes ont été étudiées en chambre de simulation atmosphérique couplée à différentes techniques analytiques (FTIR, SPME-GC/MS, PTR-MS-ToF).L’étude spectroscopique se concentre sur la détermination des spectres d’absorption UV-visible des cinq composés dans le domaine 200-400 nm à une température de 353 ± 2 K, et à une pression inférieure à la pression de vapeur saturante du COVB. Les spectres montrent une large bande d'absorption située entre 240 et 370 nm, correspondant à la bande n-π* du groupement carbonyle. L'absorption significative de ces composés au-delà de 290 nm suggère qu’ils sont susceptibles d'être décomposés par photolyse en quelques heures au minimum.Les études cinétiques en température réalisées dans cette thèse concernent la réaction (COV+ OH) pour le nopinone, le myrténal, le kétolimonène et le limononaldehdye, la réaction (COV + Cl) pour le nopinone, le myrténal et le kétolimonène et la réaction d’ozonolyse pour le kétolimonène, le myrténal et le limononaldéhyde. Les expériences ont été menées soit en utilisant la méthode cinétique relative ou la méthode cinétique absolue dans le domaine de température 298 – 353 K et à pression atmosphérique. Les résultats cinétiques obtenus ont permis de calculer les durées de vie atmosphérique de ces composés. Leur persistance atmosphérique ne dépasse pas une journée. Ces durées de vie montrent globalement que la principale voie d’élimination des composés étudiés est liée à leur réaction avec les radicaux OH avec une concurrence importante en région côtière des radicaux Cl. Par ailleurs, les études cinétiques en température ont mis en évidence une tendance générale positive avec l'augmentation de la température vis à vis des radicaux OH et de l’ozone et négative avec le chlore.Enfin des études mécanistiques d’ozonolyse concernant l’ozonolyse du kétolimonène, myrténal et limononaldéhyde ont été élaborées. Ces études consistent à suivre l’évolution temporelle des réactifs ainsi que leur produit de formation. Ces données nous ont permis d’extraire le taux de formation des produits formés lors des processus d’ozonolyse. En se basant sur ces résultats des mécanismes réactionnels d’ozonolyse du kétolimonène, myrténal et limononaldéhyde sont proposésMonoterpenes are biogenic volatile organic compounds (BVOCs) widely emitted into the atmosphere by forests and plant crops, thus representing significant players in atmospheric chemistry. Their high reactivity towards atmospheric oxidants has been the subject of several studies in the literature. However, their first-generation oxidation products are less evaluated, and could partly explain the missing reactivity and the underestimation of AOS formation by models. In this context, this study aims to understand the atmospheric reactivity of five VOCBs (nopinone, myrtenal, ketolimonene, caronaldehyde, and limononaldehyde) that are first-generation oxidation products of α- and β-pinene and limonene. This work focuses on the study of degradation processes by determining the kinetics and mechanism of oxidation reactions of the targeted BVOCs by the OH radical, chlorine and ozone, as well as their potential photolysis through the study of their UV-Vis absorption spectra. To this end, the oxidation reactions of five first-generation monoterpene oxidation products were studied in an atmospheric simulation chamber coupled with various analytical techniques (FTIR, SPME-GC/MS, PTR-MS-ToF).The spectroscopic study focused on determining the UV-visible absorption spectra of the five compounds in the 200-400 nm range at a temperature of 353 ± 2 K, and at a pressure below the saturation vapor pressure of COVB. The spectra show a broad absorption band between 240 and 370 nm, corresponding to the n-π* band of the carbonyl group. The significant absorption of these compounds above 290 nm suggests that they are likely to be removed by photolysis in at least a few hours.The temperature kinetic studies carried out in this thesis concern the (VOC+ OH) reaction for nopinone, myrtenal, ketolimonene and limononaldehdye, the (VOC + Cl) reaction for nopinone, myrtenal and ketolimonene and the ozonolysis reaction for ketolimonene, myrtenal and limononaldehyde. Experiments were carried out using either the relative or the absolute kinetic method in the temperature range 298 - 353 K and at atmospheric pressure. The kinetic results obtained made it possible to calculate the atmospheric lifetimes of these compounds. Their atmospheric persistence does not exceed one day. Overall, these lifetimes show that the main route of elimination for the compounds studied is through their reaction with OH radicals, with significant competition in coastal regions from Cl radicals. The study also revealed a generally positive trend for OH radicals and ozone with increasing temperature, and a negative trend for chlorine.Finally, mechanistic ozonolysis studies of ketolimonene, myrtenal and limononaldehyde were carried out. These studies consist of monitoring the temporal evolution of the reagents as well as the reaction product. These data allowed us to extract the formation rate of the products formed during ozonolysis processes. Based on these results, reaction mechanisms of ozonolysis of ketolimonene, myrtenal and limononaldehyde are proposed
11
Gretton, Virginia Ann. "Kinetic and mechanistic study of aquated forms of platinium (II) complexes with nucleic acid derivatives". Thesis, University of York, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359254.
Testo completo
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Appleton, Amanda Jane. "A kinetic and mechanistic study of the liquid-phase reactions of ester-substituted alkylperoxyl radicals". Thesis, University of York, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265560.
Testo completo
13
Gravestock, Thomas John. "A kinetic and spectroscopic study of chemistry relating to the atmospheric role of iodine species". Thesis, University of Leeds, 2006. http://etheses.whiterose.ac.uk/235/.
Testo completoAbstract (sommario):
The impact of halogen chemistry on important atmospheric processes such as ozone depletion and (potentially) climate regulation is becoming increasingly apparent. Yet only the most fundamental atmospheric chemistry of halogen species is included in global tropospheric models. Spectroscopic measurements of the concentration of halogen species within the Earth's atmosphere, and the accurate determination of kinetic information regarding the rates and mechanisms of chemical processes in the laboratory, greatly facilitate the evolution of our quantitative understanding of the atmospheric role of halogen species, ultimately leading to their inclusion in atmospheric chemistry models. The research presented in this thesis addresses previously un-investigated areas (or areas requiring further elucidation) of iodine chemistry. Specifically, Chapter Three uses new spectroscopic data to reassess the viability of a laser-induced fluorescence (LIF) instrument for the detection of ambient iodine monoxide radicals (10), a key species in the atmospheric chemistry of iodine, which may help to enhance our understanding of important atmospheric processes via its spatially resolved detection. Chapter Four presents a kinetic and spectroscopic investigation into the mechanism and products of the reaction of CH21 radicals with 02, which has potential implications for particle formation in the marine boundary layer (MBL). The reaction of Cl atoms with alkyl iodides, CH3I and CH212, has been studied in detail by the detection of adducts formed in these reactions, which have been observed by LIF for the first time, and is the subject of Chapter Five. As part of the course of this PhD, the reaction kinetics of the reaction of 10 with dimethyl sulphide (DMS) was investigated. The results obtained have led to a re-evaluation of the atmospheric significance of this reaction. The data obtained assist the development of our knowledge of the atmospheric chem istry of iodine species and, at a more fundamental level, the electronic structure and physical processes of gas phase species.
14
Trummer, Martin. "The effect of solid state inclusions on the reactivity of UO2 : A kinetic and mechanistic study". Doctoral thesis, KTH, Kärnkemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-33070.
Testo completoAbstract (sommario):
The release of radionuclides is a key process in the safety assessment of a deep geological repository for spent nuclear fuel. A large fraction of the release is assumed to be a consequence of dissolution of the fuel matrix, UO2. In this doctoral thesis, the kinetics and the mechanisms behind oxidative U(IV) dissolution were studied. The eects of solid phase inclusions mimicking the presence of fission products, and solutes mimicking expected groundwater components were also evaluated. Palladium, as a model substance for noble metal particle (fission products) inclusions, was shown to catalyze surface oxidation of U(IV), as well as reduction of U(VI). The second order rate constant for the surface reduction of U(VI) by H2was found to be on the order of 10-6 m s-1 (diusion controlled). Under 40 bar H2, 1 wt.% Pd was sufficient to suppress oxidative U(IV) dissolution in 2mM H2O2 aqueous solution. During g γirradiation under 1 bar H2, 0.1 wt.% Pd were sufficient to completely suppress oxidative dissolution. Under inert conditions, where H2 is only produced radiolytically, complete inhibition is observed for 3 wt.% Pd. The presence of Y2O3 as a model substance for trivalent fission products was found to decrease U(VI) dissolution significantly under inert, as well as reducing conditions. Based on kinetic data, it was shown that pure competition kinetics cannot explain the observed decrease. From experiments using pure oxidants it was shown that Y2O3 doping of UO2 decreases the redox reactivity. In addition, from experiments where hydroxyl radical formation from the catalytic decomposition of H2O2 was monitored, it could be concluded that doping has a minor influence on this process. On the basis of numerical simulations, the H2 concentration necessary to suppressradiolytic H2O2 production was found to increase with an increase in dose rate or HCO-3 concentration. Furthermore, the steady state concentration of H2O2 was found to be inversely proportional to the H2 pressure, and proportional to the square root of the dose rate. Fe2 diers strongly from the total reaction volume, the actual dose rate should not be converted into a homogeneous dose rate in numerical simulations.QC 20110511
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Dey, Benu Kumar. "A study on metal ion complexation with a macrocyclic ligand : a thermodynamic, kinetic, and mechanistic investigation". Title page, contents and abstract only, 1991. http://web4.library.adelaide.edu.au/theses/09SM/09smd528.pdf.
Testo completo
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Nilsson, Kristina. "Oxidative dissolution of doped UO2 and H2O2 reactivity towards oxide surfaces : A kinetic and mechanistic study". Licentiate thesis, KTH, Tillämpad fysikalisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-145691.
Testo completoAbstract (sommario):
Oxidative dissolution of std. UO2 and UO2 doped with Cr2O3 and Al2O3, i.e. ADOPT, induced by H2O2 and γ radiation has been the main focus in this licentiate thesis. The catalytic decomposition of H2O2 on oxides like Gd2O3, HfO2, CeO2, Fe2O3 and CuO were also investigated. A kinetic study was performed by determining first and second order rate constants together with Arrhenius parameters for the decomposition of H2O2. The reactivity of H2O2 towards the oxides mentioned was observed to differ significantly despite their similarities. In the mechanistic study, the yields and dynamics of the formation of the intermediate hydroxyl radical from the decomposition of H2O2 was determined for the oxides and found to differ considerably. A turnover point could be found for most of oxides studied, i.e. an increase in the rate of hydroxyl radical scavenging after a specific amount of consumed H2O2. The reactivity of the std. UO2 and ADOPT towards H2O2 was similar to what was observed for other UO2-based materials in previous studies. The oxidative dissolution in radiation experiments showed a slight but significant difference. This was attributed to a difference in exposed surface area instead of an effect of doping. The difference in oxidative dissolution yield was too small to be significant which supports the previous conclusion. Leaching experiments using spent nuclear fuel were also performed on the two types of fuel showing the same behavior as the unirradiated pellets, i.e., a slightly lower 238U release from ADOPT. The difference was attributed to difference in exposed surface area. The release of fission products with low UO2 solubility displayed a higher release from ADOPT which was attributed to a difference in matrix solubility. Cs was released to a larger extent from std. UO2. This is attributed to the larger grain size of ADOPT, extending the diffusion distance. The release of lanthanides and actinides was slightly higher for the conventional UO2, nevertheless the difference was relatively small.QC 20140527
17
Ahlford, Katrin. "Asymmetric transfer hydrogenation of ketones : Catalyst development and mechanistic investigation". Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-55412.
Testo completoAbstract (sommario):
The development of ligands derived from natural amino acids for asymmetric transfer hydrogenation (ATH) of prochiral ketones is described herein. In the first part, reductions performed in alcoholic media are examined, where it is found that amino acid-derived hydroxamic acids and thioamides, respectively, are simple and versatile ligands that in combination with [RhCp*Cl2]2 efficiently catalyze this particular transformation. Selectivities up to 97% ee of the corresponding secondary alcohols are obtained, and it is furthermore observed that the two different ligand classes, albeit based on the same amino acid scaffold, give rise to products of opposite configuration. The highly interesting enantioswitchable nature of the two abovementioned catalysts is studied in detail by mechanistic investigations. A structure/activity correlation analysis is performed, which reveals that the diverse behavior of the catalysts arise from different interactions between the ligands and the metal. Kinetic studies furthermore stress the catalyst divergence, since a difference in the rate determining step is established from initial rate measurements. In addition, rate constants are determined for each step of the overall reduction process. In the last part, catalyst development for ATH executed in water is discussed. The applicability of hydroxamic acid ligands is further extended, and catalysts based on these compounds are found to be efficient and compatible with aqueous conditions. The structurally even simpler amino acid amide is also evaluated as a ligand, and selectivities up to 90% ee are obtained in the reduction of a number of aryl alkyl ketones. The very challenging reduction of dialkyl ketones is moreover examined in the Rh-catalyzed aqueous ATH, where a modified surfactant-resembling sulfonylated diamine is used as ligand, and the reaction is carried out in the presence of SDS-micelles. A positive effect is to some extent found on the catalyst performance upon addition of phase-transfer components, especially regarding the catalytic activity in the reduction of more hydrophobic substrates.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: In press.
18
Pillay, Kriveshini. "A kinetic and mechanistic study on the oxidation of chromium oxide in pure chemicals and in ferrometallurgical slags". Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/5415.
Testo completoAbstract (sommario):
Bibliography: leaves 103-108.Chromium can exist in a number of oxidation states but the environmentally stable forms are trivalent (Cr(III)) and hexavalent (Cr(VI)) chromium. These two forms are noted for their different degrees of toxicity and mobility. Hexavalent chromium is more toxic and mobile and has been responsible for a number of illnesses in humans (Sheehan et. al., 1991). Elemental chromium and its compounds have a variety of uses in the industrial sector. The ferrometallurgical industry in particular makes use of chromium since this element imparts properties such as hardness and strenght to stainless steel. However, this industry also produces slags that contain residual amounts of chromium oxide (Cr[2]O[3]) along with other constituents such as calcium oxide (CaO). Thermodynamic data from the literature, has shown that Cr[2]O[3] can undergo oxidation at ambient temperature when in contact with CaO and atmospheric oxygen (Kilau and Shah, 1984; Hattori et al., 1978). Furthermore, the oxidation of Cr[2]O[3] in the presence of Ca(OH)[2] has also been observed at ambient temperature (Petersen, 1998).
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劉新權 e Sing-quan Lew. "Kinetic and mechanistic study of reactions of hydroxy, methoxy, methylthio, methylseleno and amino derivatives of some heterocyclicand homocyclic polyenes". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1991. http://hub.hku.hk/bib/B31232322.
Testo completo
20
Yang, Chunhua. "Synthesis and Kinetic Mechanism Study of Phosphonopeptide as a Dead-End Inhibitor of cAMP-Dependent Protein Kinase". Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc500671/.
Testo completoAbstract (sommario):
DL-2-Amino-4-phosphonobutyric acid, an isostere of phosphoserine, was incorporated into the heptapeptide sequence, Leu-Arg-Arg-Ala-(DL-2-amino-4-phosphonobutyric acid)-Leu-Gly, for kinetic mechanistic studies of the cAMP-dependent protein kinase. To block the phosphono hydroxyl groups, methyl, ethyl and 4nitrobenzyl esters were studied as possible protecting groups. The phosphono diethyl ester of the N-Fmoc-protected amino acid was utilized in the synthesis of the heptapeptide. Two configurational forms of the protected peptide were obtained and were separated by C18-reverse phase HPLC. Characterization of the two isomeric forms was accomplished by 3 1P NMR, 1H NMR, 13C% NMR and amino acid analysis. The protecting groups of the isomeric phsophonopeptides were removed by HBr/AcOH and purified by cation exchange HPLC. Both phosphonopeptides were found to be inhibitors of the cAMP-dependent protein kinase, having Ki values of 0.6 mM (peptide A) and 1.9 mM (peptide B).
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Thinon, Olivier. "CO conversion over dual-site catalysts by the Water-Gas Shift Reaction for fuel cell applications : comparative mechanistic and kinetic study of gold and platinum supported catalysts". Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10187.
Testo completoAbstract (sommario):
Les piles à combustible, alimentée par de l’hydrogène, représentent une solution prometteuse pour limiter la pollution. L’une des alternatives économiques envisagées à court et moyen terme est de produire l’hydrogène à partir d’un carburant tel que le méthane ou le bio-éthanol. Cette transformation a pour objectif d’obtenir un mélange de gaz riche en hydrogène avec une très faible teneur en CO, ce dernier étant un poison pour les piles de type PEM. La réaction de Water-Gas Shift (WGS) est une étape clé du procédé ; elle convertit CO en CO2 par réaction avec l’eau et fournit une quantité d’hydrogène supplémentaire. Des catalyseurs métalliques (Pt, Pd, Ru, Rh, Au, Cu) supportés sur des oxydes (CeO2, TiO2, ZrO2, Fe2O3, CeO2/Al2O3) ont été comparés dans des conditions de WGS identiques en présence de CO2 et H2. Une étude cinétique a été réalisée sur les catalyseurs Pt/CeO2, Au/CeO2, Pt/TiO2 et Au/TiO2. Les énergies d’activation apparentes et les ordres de réaction ont été déterminés à partir d’un modèle de type loi de puissance. Un mécanisme réactionnel avec deux sites a été proposé pour décrire les différentes activités des 4 catalyseurs. Des expériences de désorption programmée en température ont été réalisées pour déterminer les paramètres cinétiques sur le supportThe Fuel Cells are promising solution to reduce the air pollution. One of the cost-efficient alternatives is to produce hydrogen from another fuel such as methane or bio-ethanol. A hydrogen fuel processor consists in generating a hydrogen-rich mixture and reducing the carbon monoxide content, as PEM fuel cells are very low CO tolerance. One of these units is the water-gas shift reactor, which converts CO into CO2 by the reaction with water and provides additional hydrogen. Catalysts based on a metal (Pt, Pd, Ru, Rh, Au, Cu) supported on an oxide (CeO2, TiO2, ZrO2, Fe2O3, CeO2/Al2O3) were compared for the WGS reaction in the same conditions and in the presence of CO2 and H2. A kinetic study was conducted on catalysts Pt/CeO2, Au/CeO2, Pt/TiO2 and Au/TiO2. A power law rate model was used to determine apparent activation energies and reaction orders. A dual-site reaction mechanism was proposed to explain the different activities between the four catalysts. The sorption parameters of H2O and CO2 on the supports was quantitatively determined from temperature-programmed desorption experiments
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Buitrago, Elina. "Transition metal-catalyzed reduction of carbonyl compounds : Fe, Ru and Rh complexes as powerful hydride mediators". Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-75795.
Testo completoAbstract (sommario):
A detailed mechanistic investigation of the previously reported ruthenium pseudo-dipeptide-catalyzed asymmetric transfer hydrogenation (ATH) of aromatic ketones was performed. It was found that the addition of alkali metals has a large influence on both the reaction rate and the selectivity, and that the rate of the reaction was substantially increased when THF was used as a co-solvent. A novel bimetallic mechanism for the ruthenium pseudo-dipeptide-catalyzed asymmetric reduction of prochiral ketones was proposed. There is a demand for a larger substrate scope in the ATH reaction, and heteroaromatic ketones are traditionally more challenging substrates. Normally a catalyst is developed for one benchmark substrate, and a substrate screen is carried out with the best performing catalyst. There is a high probability that for different substrates, another catalyst could outperform the one used. To circumvent this issue, a multiple screen was executed, employing a variety of ligands from different families within our group’s ligand library, and different heteroaromatic ketones to fine-tune and to find the optimum catalyst depending on the substrate. The acquired information was used in the formal total syntheses of (R)-fluoxetine and (S)-duloxetine, where the key reduction step was performed with high enantioselectivities and high yield, in each case. Furthermore, a new iron-N-heterocyclic carbene (NHC)-catalyzed hydrosilylation (HS) protocol was developed. An active catalyst was formed in situ from readily available imidazolium salts together with an iron source, and the inexpensive and benign polymethylhydrosiloxane (PMHS) was used as hydride donor. A set of sterically less demanding, potentially bidentate NHC precursors was prepared. The effect proved to be remarkable, and an unprecedented activity was observed when combining them with iron. The same system was also explored in the reduction of amides to amines with satisfactory results.At the time of doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.
23
Lee, Lok Yan. "Study of the photodegradation and photostability of anti-cancer drugs in different media towards the development of both new actinometers and liquid formulations". Thesis, De Montfort University, 2016. http://hdl.handle.net/2086/12188.
Testo completoAbstract (sommario):
This study aims at tackling some of the problems often encountered in photostability testing and liquid formulation development. Three anti-cancer drugs will be employed as models; Dacarbazine (DBZ) has well established photostability issues, Axitinib (AXI) and Sunitinib (SUT) are two new drugs only commercially available in solid dosage forms. In ethanol, the photokinetics of these drugs were well described by the newly proposed Φ-order kinetic mathematical model. This has confirmed the photoreversible character of AXI and SUT’s and unimolecular photoreaction of DBZ’s photodegradations. Also, the Φ-order kinetics is proven to describe them better than the usually used classic thermal reaction orders. In aqueous solution, the drugs were found to undergo thermal and photochemical complex degradations, involving at least 3 photoproducts. A new photokinetic approach has been proposed in this work to solving and unravelling the attributes of such complex mechanisms. For the first time, the quantum yields (QY) of the three drugs were determined and found to increase with irradiation wavelength. SUT’s QY were comparable in ethanol and water (QY460 = 0.02), DBZ was found to be more photoefficient in water (QY330 = 0.04 and 0.1, respectively) and AXI in water (QY330 = 0.06 and 0.03). Φ-order kinetics’ potential for the development of reliable actinometers of the three drugs, without prior knowledge of unknown reaction parameters, has also been established. A general equation to describe the isotherm of a (Gn:Hm) guest-host multicomponent complex was proposed in this work to palliate the lack of a strategy for characterising nanosponge-drug complexes. It provides information on both stiochiometry and association constant of the complex. The results indicate that hydrophobic AXI forms a 1:0.8 complex, indicating the possibility of multiple association sites and/or different types of binding. The newly developed AXI/nanosponge liquid formulation has significantly increased solubility (5000-fold) and thermal stability. Furthermore, the photostability of DBZ and SUT were considerably improved by using a strategy based on light-absorption competitors. Their initial velocities reduced from 10 and 3 s-1 (respectively) to 1 and 0.13 s-1. The successful application of these methods to the model anti-cancer drugs has set out new approaches that might be found useful for future treatments of photodegradation data, development of drug-actinometers and liquid formulations of drugs.
24
Christmann, Julien. "Photochimie moléculaire des processus de photopolymérisation : de l'étude mécanistique à la modélisation cinétique". Thesis, Mulhouse, 2017. http://www.theses.fr/2017MULH0698.
Testo completoAbstract (sommario):
Ce travail de thèse aborde l’étude mécanistique de systèmes photoamorceurs complexes et la modélisation cinétique du processus de photopolymérisation. Dans un premier temps, le mécanisme photochimique d’un système combinant le [Ru(bpy)3]2+ et des agents RAFT pour l’amorçage et le contrôle d’un processus radicalaire a été étudié. Un transfert d’énergie a été clairement démontré, contredisant le mécanisme de transfert d’électron généralement proposé. Un système photoamorceur à 3 composants bicyclique dual ITX/IOD+/RSH a ensuite été considéré pour la synthèse de matériaux hybrides organiques-inorganiques. Sous excitation lumineuse, ce système produit simultanément des radicaux et des protons, permettant d’amorcer, respectivement, des processus de polymérisation radicalaire et sol-gel. Dans un second temps, l’interdépendance entre les cinétiques de photopolymérisation et l’évolution des propriétés du milieu réactionnel a été étudiée par le biais du développement d’un modèle cinétique permettant la simulation de l’intégralité du processus de photopolymérisation. Des systèmes photoamorceurs de complexité croissante ont été inclus afin d’étudier les spécificités de leurs cinétiques. Un système de type I a permis de mettre en évidence les modes de terminaison majoritaires et leur évolution au cours de la synthèse des polymères, tandis que le rôle non négligeable du transfert d’électron inverse a été mis en exergue pour des systèmes photoamorceurs de type II. La fonction d’agent de terminaison d’un photoproduit issu d’un colorant cationique, ainsi que certaines spécificités des systèmes photocycliques à 3 composants, ont été finalement étudiés grâce à la modélisationThis thesis deals with the mechanistic study of complex photoinitiating systems and the kinetic modeling of the photopolymerization process. In a first time, the photochemical mechanism of a system combining [Ru(bpy)3]2+ and RAFT agents for the initiation and control of a radical process has been studied. An energy transfer has been clearly demonstrated, contradicting the electron transfer mechanism generally proposed. A dual bicyclic three-component photoinitiating system ITX/IOD+/RSH has been considered for the synthesis of organic-inorganic hybrid materials. Under light exposure, this system produces simultaneously radicals and protons, enabling the initiation of a radical polymerization and a sol-gel process, respectively. In a second time, interdependence between photopolymerization kinetics and evolution of the medium’s properties has been studied, through developing a kinetic model for the simulation of the whole photopolymerization process. Photoinitiating systems of growing complexity have been included in order to study specificities of their kinetics. A type-I system has shown major termination modes and their evolution during the polymer synthesis, while the non-negligible role of back electron transfer has been highlighted for type-II photoinitiating systems. Role of terminating agent of a photoproduct based on a cationic dye, as well as some specificities of photocyclic three-component systems, have been finally studied with the model
25
Blythe, P. John. "Enhanced droplet nucleation in miniemulsion polymerization : a kinetic and mechanistic study /". Diss., 1998. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:9919146.
Testo completo
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Hong, Jinmo. "Effects of agitation in emulsion polymerization---Kinetic and mechanistic study of coagulum". 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3341183.
Testo completo
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Chen, Li-Yang, e 陳立揚. "Ab initio mechanistic and kinetic study of Clx (x=1,2) reactions with HCOOH and HOCO". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/nqq429.
Testo completoAbstract (sommario):
碩士國立交通大學
應用化學系碩博士班
103
The photochemical reactions between chlorine molecules and formic acid are chain reactions which proceed at least partially via chlorofomic acid and the final products detected experementally are carbon dioxide and hydrogen chloride. In order to understand the mechanism of the chain reaction, the Gaussian code was utilized to simulate the reactions of Clx (x=1, 2) with HCOOH and HOCO at the CCSD(T)/aug-cc-pVTZ//BHandHLYP/6-311++G(3df,2p) level of theory. The reactions involved are HCOOH + Cl¬2, HOCO + Cl2, HCOOH + Cl and HOCO + Cl. The HCOOH + Cl2 reaction forms HCOOCl + HCl, with a barrier height of 52.2 kcal mol-1. The rate constant predicted with the transition-state theory is 9.30x10E(-21)T^(2.07)exp(-24404/T) cm3 molecule-1 s-1 in the temperature range from 100 to 2000 K. In the HOCO + Cl2 reaction, HCl + CO2 + Cl are produced via a chlorine atom with a statble complex of chloroformic acid, which fragment with a barrier of 5.3 kcal mol-1. The rate constant predicted with the transition-state theory is 1.73x10E(-17)T^(1.55)exp(893/T) cm3 molecule-1 s-1 in the temperature range from 298 to 2000 K. The hydrogen abstraction from HCOOH by Cl atom is considered as the key process in the chain reaction. In this reaction channel, the barrier height for formation of HOCO + HCl was found to be 2.1 kcal mol-1 and the predicted rate constant is 1.7x10E(-13) cm3 molecule-1 s-1 at 298 K, which is in good agreement with an experimental value of 1.8x10E(-13) cm3 molecule-1 s-1. In the HOCO + Cl reaction, the Cl atom can form a stable complex(ClCOOH) with HOCO, which lies -79.7 kcal mol-1 relative to the reactants; the complex decomposed readily into HCl + CO2 via a transition state with a barrier of 23.4 kcal mol-1. The predicted rate constant is 4.1x10E(-11) cm3 molecule-1 s-1 at 298 K, which is in good agreement with an experimental value of 4.8x10E(-11) cm3 molecule-1 s-1.
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Ly, Hoa D. "A detailed kinetic and mechanistic study of a retaining a[alpha]-1,4-galactosyltransferase from Neisseria meningitidis". Thesis, 2002. http://hdl.handle.net/2429/13537.
Testo completoAbstract (sommario):
Lipopolysaccharyl α-1,4-galactosyltransferase C (EC 2.4.1.x, LgtC) from
Neisseria meningitidis is an important enzyme in the biosynthesis of lipooligosaccharides
in this bacterium. The reaction catalyzed by this enzyme is the transfer of a galactosyl
moiety from uridine diphosphogalactose (UDPGal) to a lipooligosaccharide acceptor
containing a galactose residue at the nonreducing terminus, forming a Gal-α-1,4-Gal
linkage in the process. Because the reaction proceeds with net retention of
stereochemistry at the centre undergoing substitution, LgtC is classified as a "retaining"
glycosyltransferase. By analogy with the well studied retaining glycosidases, LgtC is
therefore believed to follow a double displacement mechanism involving the formation
and subsequent breakdown of a covalent glycosyl-enzyme intermediate.
A detailed kinetic and mechanistic characterization of LgtC was carried out. This
enzyme was found to be highly specific for the donor substrate, UDPGal, binding this
compound with micromolar affinity. As for the acceptor substrate, the enzyme is far less
selective, as a range of compounds was found to be capable of fulfilling this role. In the
absence of suitable glycosyl acceptors, water was also found to be capable of functioning
in such a capacity, with the result being hydrolysis of UDPGal to yield UDP and
galactose. Since the reaction catalyzed by LgtC involves the binding of two substrates
and the release of two products, an understanding of the order in which these events
occur is also important to the characterization of this enzyme. On the basis of kinetic
studies together with a UDPGal/UDP exchange study, LgtC was deduced to follow a
sequential kinetic mechanism, which requires that all substrates be bound to the enzyme
before any chemical catalysis and release of products can occur. Further clarification of the order of substrate binding and product release was then achieved through a series of
inhibition studies with both substrate analogues and product. On the basis of these
studies, LgtC was concluded to follow an ordered Bl Bl kinetic mechanism in which
UDPGal binds first, followed by lactose. After catalysis, the trisaccharide is the first
product to be released, followed by UDP.
In our quest to understand the chemical mechanism of LgtC, much effort was
directed towards the attempted trapping of the putative covalent glycosyl-enzyme
intermediate and identification of the nucleophile involved in its formation. When these
endeavours were unsuccessful, alternatives to the double displacement mechanism,
wherein the nucleophile is not enzymic were then sought. With the aid of the threedimensional
structure of this enzyme, all candidate nucleophiles were identified and
assessed for their ability to fulfill such a role. Unfortunately, none appeared to be likely
to function in such a capacity. Another possibility is that LgtC does not employ a double
displacement mechanism, but rather proceeds through an Swi-like mechanism involving
the approach of the nucleophile from the same side of the reaction centre as the departing
leaving group. However, such a mechanism is not well precedented and no concrete
evidence is available to support its occurrence in LgtC. Therefore, at this point in time,
the mechanism by which LgtC catalyzes its glycosyl transfer reaction is still a mystery.
29
Rim, Guanhe. "Coupled Kinetic and Mechanistic Study of Carbonation of Silicate Materials with Tailored Transport Behaviors for CO2 Utilization". Thesis, 2020. https://doi.org/10.7916/d8-dkqh-fz87.
Testo completoAbstract (sommario):
Since the industrial revolution, the atmospheric CO2 concentration has steadily increased due to the combustion of fossil fuels, reaching 410 ppm. According to the 2018 IPCC report, it was recognized that the anthropogenic greenhouse gas emissions caused by human activities are major drivers for global warming of 1.0 oC above the pre-industrial level. Due to the unprecedented scale of human driven CO2 emission and its environmental impact, the mitigation of climate change requires a wide range of multifaceted solutions. Thus, enormous global efforts have been placed on the development of Carbon Capture, Utilization, and Storage (CCUS) to mitigate CO2 emissions in the immediate future.
Most recent reports by the U.S. National Academies and the Mission Innovation presented that ex-situ carbon mineralization is a CO2 utilization technology with a great carbon storage potential and a large market size. Also, fixing CO2 into a solid matrix of carbonate minerals is one of the most permanent methods for carbon storage. Although the ex-situ carbon mineralization presents many advantages and great potential as CCUS technology, its commercialization has been limited due to the mammoth scale of the process, slow reaction kinetic between CO2 and silicate minerals, and high energy and operating cost. In order to minimize energy and chemical (acid and base) consumption of this technology, recent researches have been focused on a two-step carbon mineralization via Pco2 swing using highly reactive heat-treated serpentine mineral. However, the elemental (Mg and Si) extractions from the complex silicate structures of heat-treated serpentine are still poorly understood and a more fundamental understanding of the Pco2 swing process is required to develop a commercial-scale plant.
Thus, the objectives of this study are directed toward addressing these technical challenges. The effect of operating conditions, such as temperature, slurry density, and CO2 partial pressure, on the dissolution of heat-treated serpentine and subsequent Mg-carbonate precipitation behaviors, were studied to provide a fundamental understanding of the Pco2 swing carbon mineralization process of highly reactive silicate materials. The dissolution experiments with a wide range of temperature and slurry densities provided valuable insights into the formation of the Si-rich passivation layer and its role in the mass transfer limitation during mineral dissolution. The heat-treated serpentine dissolution behaviors with chemical additives (ligand) were also investigated to overcome the effect of the Si-rich passivation layer on Mg extraction kinetics.
What is more, a unique internal grinding system was proposed and integrated with the Pco2 swing process to physically remove the Si-rich passivation layer. The diffusion-limited slow elemental (Mg and Si) extraction from the heat-treated serpentine silicate structures was significantly enhanced in the internal grinding system. A stress intensity, which is proportional to the energy transferred from grinding media to the heat-treated serpentine particles during a stress event, was used to describe the effect of the reaction parameters on the extent of the physical activation and the enhancements in mineral dissolution.
For the fundamental understanding of the complex dissolution behaviors of heat-treated serpentine, the changes in the silicate structures (Q0 – Q4) of heat-treated Mg-bearing mineral (serpentine) exposed to a CO2-water system (carbonic acid) was investigated using 29Si MAS NMR and XRPD. The identified silicate structures were employed to provide insight into how Mg and Si are liberated from the different silicate structures during the dissolution process.
Thermodynamic and kinetic modeling was performed to understand the Mg-carbonate precipitation behaviors in the Pco2 swing process. The effects of carbonic anhydrase, seed particles, and ligand (citrate) on precipitation behaviors were studied to improve the precipitation kinetics. This approach will bring a great paradigm shift in the energy and environmental field since the less energy-intensive and low-cost ex-situ carbon mineralization process via Pco2 swing will be able to allow long-term and sustainable carbon utilization.
30
Stolle, Achim [Verfasser]. "Study on the pyrolysis behavior of some monoterpenes and monoterpenoids : a mechanistic and kinetic overview / von Achim Stolle". 2008. http://d-nb.info/992456029/34.
Testo completo
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Nikolayenko, Varvara I. "A kinetic and mechanistic study of dinuclear platinum (II) complexes with bis-(4'-terpyridyl)-a,w-alkyldiol ligands". Thesis, 2012. http://hdl.handle.net/10413/9224.
Testo completoAbstract (sommario):
A series of novel Bis 2,2':6',2″-terpyridinyl ligands, linked through a flexible alkyl chain situated at the 4' position, were synthesised and characterised by microanalysis, FTIR, NMR, UV-Visible spectroscopy, and MS-ToF. Single crystals of all the ligands were obtained, of which one has been published, one has been submitted for publication and one is in preparation for publication. These ligands were then coordinated to platinum(II) and characterised, including ¹⁹⁵Pt NMR spectroscopy. A detailed kinetic study involving the substituting the chloride co-ligand with the following nucleophiles thiourea, 1,3-dimethyl-thiourea and 1,1,3,3-tetramethyl-thiourea was conducted using stopped-flow
techniques. An associative reaction mechanism was suggested for the pendant ligand substitution and the following trend in reactivity was observed: L2-Ptα > L3-Ptβ > L1-Ptχ. UV-Visible absorption spectra were recorded on sequentially diluted solutions of the ligands (in chloroform), and the platinum complexes (in water). These spectra obeyed the Beer-Lambert law. The values of the molar absorption coefficients at the wavelengths of maximum absorption for the ligands followed the trend L1 < L2 < L3, whilst for the complexes the trend was L1-Pt < L3-Pt < L2-Pt. It has been concluded that at low concentrations L2-Pt and L3-Pt undergo intramolecular folding. Variable temperature and variable concentration NMR spectroscopic studies were performed on all three complexes. At higher complex concentrations intermolecular self-association takes place for L2-Pt and L3-Pt but not for L1-Pt. The reactivity of the complexes is predominately determined by their structural conformations in solution. At low concentrations the L1-Pt complex remains in its linear conformational state, whilst the L2-Pt and L3-Pt complexes undergo intramolecular folding with the formation of an axial Pt—Pt bonded and π—π stacked
dinuclear platinum terpyridine centre. The latter is believed to be more active in the substitution reaction than the original mononuclear centre. The reasons for the folding and self-association in the L2-Pt and L3-Pt systems are related to the steric crowding and stress
in the spacer region of the folded or self-associated complexes.Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.
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Shaira, Aishath. "A kinetic and mechanistic study into the substition behaviour of Plantinum (II) Polypyridyl complexes with a series of Azole Ligands". Thesis, 2010. http://hdl.handle.net/10413/8864.
Testo completoAbstract (sommario):
A novel platinum(II) complex, [Pt{4-(o-tolyl)-6-(3˝-isoquinoyl)-2,2´-bipyridine}Cl]SbF6 (Pt4) was synthesized and characterised by means of infrared, elemental analysis, mass spectroscopy, and NMR spectroscopy.
Substitution kinetics of chloride ligand from square planar platinum(II) complexes namely; [Pt(2,2´:6´,2˝-terpyridine)Cl]Cl·2H2O (Pt1), [Pt{2-(2´-pyridyl)-1,10-phenanthroline}Cl], (Pt2), [Pt{4´-(o-tolyl)-2,2´:6´,2˝-terpyridine}Cl]CF3SO3 (Pt3) and [Pt{4´-(o-tolyl)-6-(3˝-isoquinoyl)-2,2´-bipyridine}Cl]SbF6 (Pt4) were studied using a series of five-membered heterocyclic neutral nitrogen donor nucleophiles, viz. pyrazole (Pz), triazole (Tz), imidazole (Im), 1-methylimidazole (MIm) and 1,2-dimethylimidazole (DMIm) under pseudo first-order conditions in methanol. The kinetics of the substitution reactions were studied as a function of concentration of the nucleophiles at different temperatures using UV/Visible spectrophotometry and conventional stopped-flow techniques. The observed second-order rate constants, k2 followed a two term rate law kobs = k2[Nucleophile] + k-2 except for 1,2-dimethylimidazole with Pt1, Pt3, Pt4 and Pz and Tz with Pt1. The observed second-order rate constants along with the negative entropies of activation support an associative mode of substitution behaviour.
The results obtained indicate that increasing the π-conjugation in the cis and cis/trans position influences the rate of substitution reactions. Increasing the π-conjugation in the cis position decreases the rate of the substitution reactions by decreasing the π-acceptor property of the terpy moiety. On the other hand, increasing the π-conjugation in the cis/trans position increases the rate of substitution reaction by enhancing the π-acceptor property within the ligand framework. This in turn increases the electronic communication, which consequentially decreases the frontier orbital energy gap between HOMO and LUMO and hence increases the reactivity of the metal centre. Thus the observed trend for the reactivity was Pt2 > Pt1 > Pt3 > Pt4. The observed kinetic trend was further supported by DFT-calculations obtained from the computational analysis carried out for the complexes.
The substitution kinetics was influenced by the basicity of the incoming nucleophiles. Except for the sterically hindered nucleophile, DMIm, the pKa of the entering nucleophiles followed a Linear Free Energy Relationship (LFER) indicating an increase in the substitution reactions with increase in the basicity of the nucleophile. The general trend observed for the reactivity of the nucleophiles is MIm > Im > DMIm > Pz > Tz.
In the reverse reactions the replacement of the azoles by the chloride was controlled by the strength of the Pt—N(azole) bond which is dependent on the strength of the extent of the π-back-bonding between the platinum centre and the azole.Theses (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.
33
Gómez, Martín Juan Carlos [Verfasser]. "Studie zur Spektroskopie, Reaktionskinetik und zum Mechanismus der in der Atmosphäre relevanten J2-O3-Photochemie = Spectroscopic, kinetic and mechanistic studies of atmospherically relevant I2, O3 photochemistry / von Juan Carlos Gómez Martín". 2006. http://d-nb.info/982121849/34.
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Zhao, Chunli. "Operando spectroscopic and kinetic study of the selective oxidation of propylene to acrolein over well-defined supported vanadium oxide catalysts". 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3285758.
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Ching-Shuenn, Yang, e 楊慶順. "Kinetic and Mechanistic Study for the Reaction of Carbonylation , Transpositional Isomerization,and Carbon Monoxide Deinsertion of .alpha.-Ketoacyl Platinum(II) Complexes". Thesis, 1994. http://ndltd.ncl.edu.tw/handle/19620625776679617368.
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Schumacher, Birgit [Verfasser]. "Investigation of the CO oxidation on highly disperse Au-TiO2 catalysts in H2-rich and H2-free atmosphere : a kinetic and mechanistic study / Birgit Schumacher". 2005. http://d-nb.info/1000525309/34.
Testo completo