Siga este link para ver outros tipos de publicações sobre o tema: Dithiocarbamates.
Teses / dissertações sobre o tema "Dithiocarbamates"
Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos
Veja os 50 melhores trabalhos (teses / dissertações) para estudos sobre o assunto "Dithiocarbamates".
Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.
Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.
Veja as teses / dissertações das mais diversas áreas científicas e compile uma bibliografia correta.
1
McMaster, Claire. "Radical mediated reactions of dithiocarbamates". Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/3886/.
Texto completo da fonteResumo:
Chapter one reviews the use of acyl radicals and the various functional groups from which they have been derived. The earlier work on the use of dithiocarbamates as a source of acyl radicals has been progressed. Systems with the potential to follow either a 6-exo or competing 7-endo cyclisation pathway have been made. Chapter two is about the radical mediated reduction of the dithiocarbamate group. Previously reported dithiocarbamate group transfer reactions are reviewed along with existing methods for the reductive removal of the dtihiocarbamate and related xanthate groups. The development of conditions for a general method of the reduction is reported, with various examples being shown. Chapter three begins with a review of the synthesis of a range of twisted amides. The formation of a twisted amide precursor, containing a dithiocarbamate groups is reported. The attempts to form the bicyclic twisted amide, by used of carabamoyl radicals generated from dithiocarbamates are described. Chapter four discusses previous attempts at the synthesis of the natural occurring compound stemofoline. The attempted formation of the dithiocarbamate containing precursor for a 7-endo-trig cyclisation, 5-exo-trig transannular cyclisation, group transfer reaction to give the azatricyclic system, analogous to the tricyclic core of stemofoline is discussed.
2
Cox, Michael Jason. "Zinc, cadmium and mercury 1,1-dithiolates /". Title page, abstract and contents only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phc8775.pdf.
Texto completo da fonte
3
Ahmed, Mohammed A. K. "Synthesis and physical investigation of tellurium dithiocarbamates". Thesis, Aston University, 1985. http://publications.aston.ac.uk/11726/.
Texto completo da fonte
4
Exarchos, George. "Reactions between metal sulfur chelate complexes and class B metal centres". Thesis, King's College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312991.
Texto completo da fonte
5
Fiddy, J. M. "A Moessbauer effect study of iron(III) dithiocarbamates". Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233819.
Texto completo da fonte
6
Roe, Stephen Mark. "Structural studies of main group metal carboxylates and dithiocarbamates". Thesis, University of Warwick, 1989. http://wrap.warwick.ac.uk/56212/.
Texto completo da fonteResumo:
The work contained in this thesis describes the crystal structures of a number of tin(IV) and tellurium(IV) carboxylates and dithiocarbamates. The results show the regularity at which these types of compounds form secondary bonds (weak interactions), and the effect of the lone pair of tellurium(IV) on the geometries formed. The area has been studied through the determination of the following crystal structures: i) monocarboxylates: Ph3SnOCOCH2Cl, Ph3SnOCOCHCh, Ph3SnOCOCCh.MeOH. Ph3SnOCOCCh and Ph3TeOCOCCh. ii) dicarboxulates : Ph2Sn(OCOCH3)2, Ph2Sn(OCOCH2CI)2 and Ph2Te(OCOCCI3)2 iii) dithiocarbamates : Ph2Te(S2CNEt2)2, Ph2Te(S2CN(Et)(Ph))2 and Ph2Te(S2CNPh2)2 In addition to these, six hydrolysis products of Ph3SnOCOCCh are reponed. These com- pounds show the varied results that are obtained from the facile dearylation of the organotin com- pound by a strong organic acid in the presence of water. The following structures are reported: Ph2 Sn(OH)(OCOCCh), {[Pb2Sn(OCOCCh)hOh (two isomers), [(PbSn))(Oh(OCOCCh)sh, [PhSn(O)(OCOCCh)]6 and [(Ph 2 Sn)2(OH)(OCOCCh)3h.
7
Duffour, Jacqueline. "Résidus des dithiocarbamates et de l'éthylènethiourée : aspects toxicologiques et analytiques". Montpellier 1, 1991. http://www.theses.fr/1991MON13511.
Texto completo da fonte
8
Boisdé, Frédéric. "Sur la mise au point de dosages immunoenzymatiques de pesticides et de leurs dérivés : le cas des dithiocarbamates et de l'éthylènethiourée". Brest, 2003. http://www.theses.fr/2002BRES2038.
Texto completo da fonteResumo:
La méthode officielle utilisée à ce jour pour le dosage des résidus de dithiocarbamates consiste en une hydrolyse acide des échantillons puis, après distillation, d'un dosage spectrophotométrique du disulfure de carbone (CS2) libéré. Ce procédé présente de nombreuses limites comme une faible reproductibilité, un seuil de détection inadapté à certains dosages et une absence de spécificité. Les méthodes classiques de dosage (chromatographies gazeuse et liquide) sont elles sensibles et spécifiques, mais nécessitent un matériel coûteux, manipulé par un personnel qualifié. De ce fait, les méthodes de dosage immunoenzymatique qui permettent, en outre, de traiter plusieurs échantillons simultanément sont apparues comme une alternative pertinente aux techniques habituellement utilisées. Nos travaux décrivent, dans un premier temps, la synthèse de molécules dont la structure est identique à celle des pesticides que l'on cherche à doser. Elles possèdent en plus un bras de liaison, généralement constitué d'un enchaînement plus ou moins long de méthylènes, fonctionnalisé à son extrémité par un acide carboxylique. Ces haptènes peuvent ainsi être couplés à la surface de protéines porteuses (BSA, Ova) par la formation de liaison amide avec leurs restes lysyles. Dans un second temps, ces différents conjugués haptènes-protéine sont utilisés soit comme immunogènes pour la production d'anticorps spécifiques des pesticides considérés ou soit comme traceurs lors de tests ELISA compétitifs pour la mise au point des dosages proprement dits. Cette étude nous a permis de développer complètement une méthode de dosage immunoenzymatique du thirame et d'obtenir des anticorps reconnaissant de manière compétitive les éthylène-bis-dithiocarbamates et un produit issu de leur dégradation, l'éthylènethiourée, reconnue comme cancérogèneTo date, the official method to be used for the measurement of dithiocarbamates residues is to first carry out an acid hydrolysis of the samples and, after distillation, to quantify the released carbone disulfure (CS2) by spectrophotometry. But, this procedure is spoilt with many drawbacks, e. G. Low reproducibility, detection threshold unsuited for certain quantifications and lack of specificity. On the other hand, the classical quantification techniques, i. E. GC and HPLC, are sensitive and specific, but require a high-cost equipment and qualified operator(s). This is why enzyme immunoassays that, in addition, allow one to process several samples at the same time have sounded as a relevant alternative to the usual techniques. We first report on the synthesis of molecules whose structure is alike that of the pesticides to be quantified. The additional arm they carry, usually, consists of a more or less long chain of methylenes and ends with a carboxylic acid function. These haptens can be linked to the surface of carrier proteins, BSA and Ova, through an amide bond with lysyl residues. Then, in a second step, these various hapten-protein conjugates were used as either immunogens for production of specific antibodies for the pesticides of interest, or tracers in competitive ELISA assays for the development of quantification protocols. This study allowed us to both develop a complete enzyme immunoassay for thirame measurement and get competitive antibodies for ethylene-bis-dithiocarbamates and one of their by-products, ethylenethiourea, known as being carcinogenic
9
Stephens, Alan Nicholas. "Niobium dithiocarbamates : structural and solution studies in relation to a bridged-dinitrogen complex". Thesis, University of Sussex, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236255.
Texto completo da fonte
10
Xu, Ximing. "Arylamines N-acétyltransférases : liaison du cofacteur, mécanisme catalytique et inhibition par les dithiocarbamates". Paris 7, 2014. http://www.theses.fr/2014PA077091.
Texto completo da fonteResumo:
Les principaux objectifs de cette thèse visent à mieux comprendre les relations structure/fonction de la famille de arylamine N-acétyltransférases (NAT) et comment ces enzymes peuvent être inhibées par un groupe important de pesticides: thiocarbamates. Afin d'obtenir de nouvelles informations sur les mécanismes moléculaires qui régissent la fixation de la AcCoA aux NAT, la première partie de mon travail a été consacrée à la détermination de la structure cristalline d'une isoforme NAT de Mesorhizobium loti ((RHILO) NAT1) en complexe avec CoA. La deuxième partie de mon travail a consisté à comprendre le rôle d'une position structuralement conservée au sein du motif conservé (Pro-Phe/Tyr-Glu-Asn ou PF/YEN) dans le site actif des NAT. L'isoforme (RHILO) NAT1 a été utilisée comme modèle pour comprendre le rôle de cette position conservée. Parallèlement aux études structure/fonction, la troisième partie de ma thèse a été consacrée à l'identification des thiocarbamates (principalement des pesticides) capables inhiber les NAT humaines et par conséquent le métabolisme d'autres pesticides via des mécanisme d'interaction «pesticide-pesticide». La plupart des travaux a reposé sur des approches moléculaires (expression d'enzymes recombinantes, cinétique enzymatique, mutagenèse dirigée, détermination de structure 3D, modélisation moléculaire) et des approches cellulaires (exposition des kératinocytes humains en culture à des amines aromatiques et des pesticides de type thiocarbamate, détection de métabolites dans des échantillons biologiques)The main goals of this thesis aimed at better understanding structure/function relationships in the family of arylamine N-acetyltransferases (NAT) enzymes and how theses enzymes could be inhibited by an important group of pesticides: thiocarbamates. In order to get further insights into the molecular mechanisms that govern the binding of the AcCoA to NAT enzymes, the first part of my work was devoted to the determination of the crystal structure of a NAT isoform of Mesorhizobium loti ((RHILO)NAT1) in complex with CoA. The second part of my work consisted in understanding the role of a structurally conserved position present in a conserved motif (Pro-Phe/Tyr-Glu-Asn or PF/YEN) in the active site of NAT enzymes. (RHILO)NAT1 isoform was used as a model to decipher the role of this conserved position. In parallel to the structure/function studies, a third part of my thesis was devoted to the identification of thiocarbamates chemicals (mainly pesticides) that could inhibit human NAT enzymes and subsequently the metabolism of other pesticides through « pesticide-pesticide » interactions. Most of the work relied on molecular (recombinant enzyme expression, enzyme kinetics, site directed mutagenesis, crystal structure determination, molecular modelling) and cellular approaches (exposure of cultured human keratinocytes to aromatic amine and thiocarbamate pesticides, detection of metabolites in biological samples)
11
Coxall, Robert Andrew. "Structural studies of some mononuclear and polynuclear metal complexes". Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299640.
Texto completo da fonte
12
Wong, Wai Cheong. "Electroanalysis of amino acids and dithocarbamates". HKBU Institutional Repository, 1994. http://repository.hkbu.edu.hk/etd_ra/40.
Texto completo da fonte
13
Padhye, Lokesh Pradeep. "Roles of polydadmacs, dithiocarbamates and activated carbons in formation of N-nitrosamine contaminants in water". Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34743.
Texto completo da fonteResumo:
N-Nitrosamines are an emerging group of disinfection byproducts characterized by high carcinogenic risks at ng/L levels and by their frequent detection in water and wastewater treatment systems in the U.S. and other parts of the world. The overall goal of this research is to achieve a better understanding of the roles of common nitrosamine precursors in leading to N-nitrosamine formation in water and wastewater treatment systems. The specific objectives of this research are: (a) To probe the mechanisms of nitrosamine formation from commonly employed water treatment polymers, particularly polyDADMACs, during ozonation, (b) To evaluate the role of dithiocarbamate compounds as nitrosamine precursors in reaction with common water disinfection oxidants, and (c) To investigate the potential enhancement effect of activated carbons (AC) to promote transformation of amines to nitrosamines and identify the involved reaction mechanism.
Results of this research show that, upon ozonation, polyDADMACs may yield N-nitrosodimethylamine (NDMA) at levels up to two orders of magnitude higher than current advisory guidelines for NDMA. Radical pathways may be responsible for the degradation of the quaternary ammonium ring groups in polyDADMACs to release of dimethylamine (DMA). Detection of significant amounts of nitrite after ozonation of polyDADMACs and DMA suggests the potential role of nitrosation pathway in NDMA formation. Study results also reveal dithiocarbamates as potent nitrosamine precursors with significant nitrosamine yields upon ozonation and monochloramination. Identification and quantification of reaction products suggest nitrosation and chlorinated-UDMH oxidation as primary reaction mechanisms in nitrosamine formation from ozonation and monochloramination of dithiocarbamates compounds, respectively. This research also demonstrates that many commercial AC materials may catalyze transformation of secondary amines to yield trace levels of N-nitrosamines under ambient aerobic conditions. This is a novel discovery with far-reaching implications because of the widespread usage of AC materials in numerous analytical and environmental applications. The study results show that the properties of AC materials and reaction conditions play a crucial role in the catalyzed nitrosamine formation and should be carefully selected to minimize analytical errors and undesirable nitrosamine formation in water samples. Overall, the mechanistic information obtained in this research will be useful for the water industry and research communities to develop more effective strategies to control undesirable nitrosamine formation in water and wastewater treatment systems and thus better protect the public health.
14
Nqombolo, Azile. "Synthesis and structural studies of NiS and PdS nanoparticles/nanocomposites from dithiocarbamates single source precursors". Thesis, University of Fort Hare, 2016. http://hdl.handle.net/10353/d1021326.
Texto completo da fonteResumo:
The main aim of this research is to synthesize Ni(II) and Pd(II) dithiocarbamate complexes and use them as single source precursors for the synthesis of NiS and PdS nanoparticles and metal sulphides potato starch nanocomposites. Four dithiocarbamate ligands were synthesized and characterized using elemental analysis and spectroscopic techniques. The ligands were used to prepared homoleptic Ni(II) and Pd(II) complexes of the dithiocarbamate ligands. The metal complexes were characterized with elemental analysis, UV-Vis, FTIR and 1H-NMR spectroscopic techniques. Conductivity measurements indicate that all the complexes are non-electrolytes in solution and results from the electronic spectra studies confirmed the proposed 4-coordinate square planar geometry around the metal ions. The nickel complexes showed d-d transitions around 477 nm while in the palladium complexes, no d-d transitions were observed but the compounds showed strong metal to ligand charge transfer transitions. From the FTIR spectra studies, it can be confirmed that the complexes were successfully synthesised because all peaks of interest were observed at expected regions from the literature. The νC-N was observed around 1469-1495 cm-1, νC=S around 1101-1188 cm-1 and νC-S around 738-1060 cm-1 for both Ni(II) and Pd(II) complexes. νNi-S was observed around 375-543 cm-1 and νPd-S around 529-545 cm-1. The FTIR also confirmed that the dithiocarbamate ligands act as bidentate chelating ligands through the sulfur atoms. The complexes were used as single source precursors and thermolysed in hexadecylamine (HDA) at 220 °C to prepare four HDA-capped nickel sulfide nanoparticles and four palladium sulfide nanoparticles. The as-prepared nanoparticles were studied with optical absorption spectra, photoluminescence, powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The optical studies results showed that NiS have large band gaps that are greater than that of the bulk, therefore they are found to be blue shifted relative to the bulk, which shows that they have small particle size and thus confirming their quantum confinement effect. PL spectra reveal that the emission peaks are red shifted compared to the absorption band edges of the nanoparticles. The XRD patterns confirmed the formation of cubic and rhombohedral phase for NiS nanoparticles and cubic phase for PdS nanoparticles. SEM images of both NiS and PdS show uniform surface morphology at low and high magnification with different shapes. EDS analyses confirmed the presence of Ni, S, and Pd in each of the spectrum indicating that the nanoparticles were successfully synthesized. TEM images showed that the synthesised nanoparticles have uniform and narrow size distribution with no agglomeration. The sizes of the NiS nanoparticles were found to be in the range of 12-38 nm for NiS1, 8-11 nm for NiS2, 9-16 nm for NiS3 and 4-9 nm for NiS4. The TEM images for the as-prepared PdS nanoparticles showed that the average crystallite sizes are 6.94-9.62 nm for PdS1, 8-11 nm for PdS2, 9-16 nm for PdS3 and 4-9 nm for PdS4 respectively. The nanoparticles were used to prepare potato starch nanocomposites and SEM images indicate that the surface morphology of starch polymer nanocomposites compose of potato starch and few particles in between the pores of the matrix, this is due to the small ratio of nanoparticles used.
15
Thorel, Thérèse. "Manipulation des mécanismes de défense anti-parasitaires et des fonctions effectrices des phagocytes mononuclées et des plaquettes sanguines par des immunomodulants exogènes". Lille 1, 1987. http://www.theses.fr/1987LIL10201.
Texto completo da fonte
16
Garcia, Con Luis Miguel. "Dormant radical technology synthesis of materials and potential applications". Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/7247.
Texto completo da fonteResumo:
This research was focused on the study of the polymer dormant radical systems, species containing free radical structures that have longer lifetimes and greater stability than radicals in general. In order to understand the nature and reactivity of the dormant radicals, polymeric systems capable of producing dormant free radicals were synthesised. In addition, the use of these novel polymeric materials in a range of applications were studied. Those applications exploited the nature of the dormant radical groups and included controlled modifications in the polymeric structure, heterogeneous catalysis and chromatographic separations.
17
Rodriguez-Garcia, Valerie. "Efficient methodology for the synthesis of 2,4-benzodiazepin-1-ones, sulfonylbenzotriazoles, sulfonamides, ethylene sulfonamides, thiocarbamates, dithiocarbamates and thioamides". [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0006303.
Texto completo da fonte
18
Landgraff, Ana Carolina Mafud. "Estudo estrutural e estereoquímico de derivados de ditiocarbamatos: supramolecularidade". Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/75/75131/tde-16092011-155830/.
Texto completo da fonteResumo:
Ditiocarbamatos (DTC) tem uma vasta gama de aplicação. Na indústria são usados como ativos para vulcanização da borracha; lubrificantes e anticorrosivos para trabalhos em alta pressão. Na medicina são estudados como potenciais inibidores do fator nuclear kappa β (NF-KB) e da protease do HIV-1; além da aplicação como indutores da apoptose em vários tipos de células carcinogênicas e como agentes antimicrobianos e antifúngicos. Derivados cíclicos de ditiocarbamatos são capazes de formar extensos arranjos no estado sólido mantidos por ligações de hidrogênio, interações do tipo π - π, interações metal - π e interações de van der Waals. No presente trabalho, determinou-se a natureza dessas interações em ditiocarbamatos derivados da própria amina substituinte e de metais alcalinos. Foram calculados mapas de potencial eletrostático molecular e momentos dipolo, a fim de entender quais fatores regem o empacotamento cristalino. Os átomos de enxofre nessas moléculas apresentam ligações mono ou bidentadas e ligações hidrogênio intramoleculares, que formam arranjos poliméricos. Essas interações são fracas, com distâncias da ordem da soma de seus raios de van der Waals, semelhante ao grafite.Dithiocarbamates (DTC) are applied in several areas such as agricultural products, pesticides and repellents; industry, as additives for vulcanization of rubber; organic synthesis as precursors; chelating agents; lubricants and antiwear at high pressure. In medical fields, they have also been applied as a potential nuclear factor kappa B (NF - κB) inhinitor; transcription factor heat shock factor 1 (HSF1); HIV-1 protease inhibitor; co-adjuvant agent in the treatment of opportunistic infections in AIDS patients; inducer of apoptosis activity in several types of cancer cells, e.g. renal cell carcinoma, breast cancer; besides being great antimicrobicial and antifungal agents. Cyclic dithiocarbamate derivates are capable of forming extended hydrogen bonded arrays in the solid state. They are kept in the solid state by hydrogen bonds, π - π interactions stacking, π - metal interactions and van der Waals interactions. This work presents eight ditihiocarbamates derivates, their syntheses and recrystallization. The analysis of the dithiocarbamates salts was performed by X-ray diffraction which has gave the influence of the ligand in the crystalline arrangement, and molecular electrostatic potential maps, by DFT calculations. The sulphur atoms in these molecules have mono or bidentate bonds and intramolecular hydrogen bonds, forming polymeric arrangements. These interactions are weak, with distances of the order of the sum of their van der Waals radii, similar to graphite.
19
De, Sousa Rodolphe. "Synthèse de dithiocarbamates de glycérol à partir de ressources renouvelables : vers des fongicides et solvants plus respectueux de l'environnement". Poitiers, 2010. http://www.theses.fr/2010POIT2313.
Texto completo da fonteResumo:
Ces travaux s'inscrivent dans le cadre du programme ANR « GlyBioSynth » qui a pour objectif de valoriser les matières premières renouvelables comme le glycérol. Dans une première partie, une étude sur le développement d'un procédé « vert » permettant la synthèse de composés dithiocarbamates dérivés du glycérol a été réalisée. Les dithiocarbamates sont actuellement utilisés comme antifongique mais la relarguage des métaux présents dans ces composés provoque une certaine écotoxicité. L'objectif de cette partie est de mettre en oeuvre la synthèse de composés dithiocarbamates dérivés du glycérol dans le but de substituer ces métaux. Deux grandes stratégies ont été explorées, (i) la substitution directe du glycérol par le sel de dithiocarbamate et (ii) la préparation in-situ d'un intermédiaire du glycérol. La seconde voie a permis la synthèse des dithiocarbamates avec de bons rendements (40-90%). De plus, l'utilisation du glycérol en tant que solvant a abouti à la mise en oeuvre d'un procédé « vert » qui a fait l'objet d’un dépôt de brevet. Dans une deuxième partie, l'utilisation du glycérol a été étudiée en tant que solvant dans une réaction en présence de catalyseurs homogènes. Les catalyseurs utilisés lors de cette étude sont des dendrimères à base de polypropylèneimine, catalyseurs basiques efficaces mais onéreux. L'un des grands défis avec les catalyseurs homogènes concerne leur recyclage. Pour cela, l'utilisation du glycérol en tant que solvant de réaction a permis l'immobilisation de ces dendrimères. Le glycérol possède deux grands atouts, (i) sa non miscibilité avec un grand nombre de solvants organiques et (ii) sa non réactivité dans nos condition opératoiresThis work was carried out in the frame of the ANR program « GlyBioSynth » which has for objective to value raw renewable material as glycerol. In a first part, a study of the development of a “green” process allowing the synthesis of dithiocarbamates derived from glycerol was realized. Dithiocarbamates is nowadays used as antifungal but the release of metals present in these compounds causes certain toxicity. The objective of this part is to develop the synthesis of dithiocarbamates compounds derived from glycerol with the aim of substituting these metals. Two strategies were investigated, i) the direct substitution of glycerol by the salt of dithiocarbamate and ii) the preparation in-situ of an intermediary of glycerol. The second way allowed the synthesis of dithiocarbamates with good yields (40-90%). Furthermore, the use of the glycerol as solvent resulted in the development of a “green” process which has been the object of a patent. In a second part, the use of the glycerol was studied as solvent in a reaction in the presence of homogeneous catalysts. Catalysts used during this study are dendrimers based in polypropyleneimine, which are effective basic catalysts but expensive. One of the challenges with the homogeneous catalysts concerns their ability to recycle. For that purpose, the use of glycerol as solvent allowed the immobilization of these dendrimers. Glycerol has two advantages, i) an immiscibility with a large number of organic solvents and ii) the absence of reaction in these conditions
20
Thangwane, Selaelo Christabel. "Synthesis and characterization of substituted dithiocarbamates ligands and complexes as a source of metal (Pb, Ni & Co) sulphide nanoparticles". Thesis, Vaal University of Technology, 2017. http://hdl.handle.net/10352/396.
Texto completo da fonteResumo:
M. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology.Lead, nickel and cobalt dithiocarbamates complexes were synthesized using methanol and water as solvents. All complexes were refluxed at 60 °C, cooled at room temperature, washed with methanol to remove the impurities and dried under the fume hood. A combination of Fourier transformer infrared (FTIR), elemental analysis (EA) and thermogravimetric analysis (TGA) were used to characterize these complexes. There was shifting of bands from low to high frequencies of the dithiocarbamates complexes compared to benzimidazole derivatives. The absence of the N-H band and the presence of new C=S bands confirmed that the complexes can be used in the preparation of metal sulphide nanoparticles. Elemental analysis showed that there was a percentage mismatch for the complexes I, III, IV and V. Complexes II and VI calculated percentages were within the limits with the found percentages except for sulphur which was low. The TGA curves decomposed to form a mixture of metal and metal sulphides for complex I, II, III and IV except for complex VI which gave metal sulphide only. All benzimidazole complexes decomposed at higher temperatures and were considered as stable complexes. Lead sulphide (PbS) is an important group IV-VI metal chalcogenide semiconductor. It has a direct narrow band gap of 0.41 eV at 300K and a large excitonic Bohr radius of 18 nm. Lead sulphide absorption band can be tuned to anywhere between near IR to UV (0.4μm) covering the entire visible spectrum, while achieving the quantum confinement region. The synthesis of lead sulphide nanoparticles was conducted by varying the effect of the reaction conditions such as the type of capping agents and temperature. Lead dithiocarbamate complex derived from benzimidazole, [Pb(S2N2C8H5)2] was thermolysed in hexadecylamine (HDA) and trioctylphosphine oxide (TOPO) at different reaction temperatures (140, 160 and 180 °C) to produce HDA and TOPO capped PbS nanoparticles. The nanoparticles were characterized using X-ray diffraction (XRD) for structural analysis, transmission electron microscopy (TEM) for shape and size, Ultraviolet visible (UV/Vis) and Photoluminescence (PL) spectroscopy for optical properties. An increase in temperature gave a decrease in the sizes of the nanoparticles when using the HDA capped lead benzimidazole dithiocarbamate complex. The observed morphology was cubes. TOPO capped lead benzimidazole dithiocarbamate complex gave no specific trend when temperature was varied. A cross-like layer with quasi spherical particles on top was observed at 160 °C. At 180 °C, the cross-like layer decomposed into rods- like materials with quasi spherical particles on top for TOPO capped PbS nanoparticles. For lead 2-methylbenzimidazole [Pb(S2N2C9H7)2] dithiocarbamate complex, TOPO capped PbS produced agglomerated cubic morphology at low temperature but as the temperature was increased agglomerated cylindrical shapes were observed. HDA capped PbS produced polydispersed nanocubes which were increasing in size when the temperature was increased. Nanoparticles displayed a blue shift in band edges with good photoluminescence behaviour which was red shifted from their respective band edges all temperatures and capping agents. XRD confirmed the crystal structure of cubic phase (galena) of PbS at all temperatures except for HDA capped PbS nanoparticles at 140 °C from lead benzimidazole dithiocarbamate complex which confirmed the crystal structure of face-centred cubic phase of PbS nanoparticles. Nickel sulphide has much more complicated phase diagram than cobalt sulfides and iron sulfides. Their chemical composition has many crystalline phases such as α-NiS, β=NiS, NiS2, Ni3S2, Ni3S4, Ni7S6 and Ni9S8. Ni3S2 phase has shown potential as a low-cost counter electrode material in dye sensitised solar cells, while the α-NiS phase has been applied as a cathode Material in lithium-ion batteries. The synthesis of nickel sulphide nanoparticles was done by varying the effect of the reaction conditions such concentration and temperature. Nickel benzimidazole dithiocarbamate [Ni(S2N2C8H5)2] and nickel 2-methylbenzimidazole [Ni (S2N2C9H7)2] dithiocarbamates complexes were thermolysed in hexadecylamine (HDA) at different reaction temperatures (140, 160 and 180 °C) and precursor concentrations (0.30, 0.35 and 0.40 g) to produce HDA capped NiS nanoparticles. It was observed that increasing both temperature and precursor concentration increased the size of the nanoparticles. Anisotropic particles were observed for both complexes when varying precursor concentration and temperature. Nickel benzimidazole dithiocarbamate complex produced stable shapes (spheres and cubes) of nickel sulphide nanoparticles. Nickel 2-methylbenzimidazole dithiocarbamate complex produced a mixture of spheres, cubes, triangles and rods nickel sulphide nanoparticles at all concentrations. But when varying temperature, it only produced that mixture at 160 °C. The optical measurements supported the presence of smaller particles at all temperatures and concentrations. XRD showed the presence of C7OS8 and pure nickel as impurities. However, the crystal structure of cubic Ni3S4 was observed at low temperatures and an introduction of monoclinic NixS6 at high temperature (180 °C) when varying temperature for both complexes. When varying concentration using nickel benzimidazole dithiocarbamate complex, XRD showed the presence of NiSO4.6H2O impurities at high temperatures. At 160 °C a mixture of hexagonal NiS and cubic Ni3S4 was observed. At low temperatures only nickel as a metal was found as an impurity and the crystal structure of cubic Ni3S4 was observed. When nickel 2-methylbenzimidazole complex was used, C7OS8 and pure nickel were found as impurities but the crystal structure of cubic Ni3S4 was observed. Cobalt sulphide (CoS) belongs to the family of group II-IV compounds with considerable potential for application in electronic devices. They have a complex phase diagram and their chemical composition have many phases such as Co4S3, Co9S8, CoS, Co1-xS, Co3S4, Co2S3 and CoS2. The synthesis of cobalt sulphide nanoparticles was conducted by varying the effect of temperature on size and shape of the nanoparticles. Nickel benzimidazole dithiocarbamate, [Ni(S2N2C8H5)2] and nickel 2-methylbenzimidazole [Ni(S2N2C9H7)2] complexes were thermolysed in hexadecylamine (HDA) at different reaction temperatures (140, 160 and 180 °C) to produce HDA capped CoS nanoparticles. Cobalt benzimidazole dithiocarbamate complex produced close to spherical shapes nanoparticles at all temperatures. The images showed that as temperature was increased, the size of the particles decreased. All the main reflection peaks were indexed to face-centred cubic Co3S4 and there were some impurities of C7OS8 at all temperatures. The optical measurements supported the presence of smaller particles at all temperatures. Cobalt 2-methylbenzimidazole dithiocarbamate complex produced big and undefined morphology. The optical properties were also featureless and XRD only showed impurities of C7OS8. The impurity is thought to be generated from a side reaction between benzimidazole and carbon disulphide to give this persistent organic moiety.
21
Debbarh, Ikram. "Etude du passage des ethylène-bis-dithiocarbamates dans le liquide cephalorachidien et dans les urines chez le rat et application chez l'homme". Bordeaux 2, 2001. http://www.theses.fr/2001BOR28886.
Texto completo da fonteResumo:
Une étude épidémiologique réalisée en Gironde a mis en évidence chez les viticulteurs l'existence d'une association entre l'exposition prolongée à des pesticides et des affections neurologiques. Les Ethylène Bis Dithiocarbamates (EBDCs) comme le Mancozèbe sont largement utilisés dans cette région. Il existe une forte présomption d'un effet de ce groupe sur le système nerveux central. La survenue de la maladie de Parkinson chez des sujets longtemps exposés aux EBDCs est déjà rapportée. Au cours des 10 dernières années, les appels reçus au centre anti-poison de Bordeaux concernant l'exposition à ces fongicides montre dans 50 % des cas des symptômes neurologiques. La toxicité de ces fongicides est souvent associée à leur métabolite commun l'éthylène thiourée (ETU). La neurotoxicité implique à priori le passage intracérébral ou au moins dans le liquide céphalorachidien (LCR) des toxiques présumés. Nous avons donc étudié la métabolisation et la diffusion des EBDCs et l'ETU chez le rat. Dans le contexte d'un tel objectif, nous avons mis au point et validé des méthodes simples de détection et de quantification des EBDCs et leur métabolite commun l'ETU dans les différents milieux biologiques. Environ 4 % du Mancozèbe administré par voie orale est excrété inchangé dans les urines et 4,9 % est métabolisé en ETU qui persiste pendant au moins 3 jours dans la circulation générale. Bien que la diffusion de l'ETU dans le LCR soit largement supérieure à celle du Mancozèbe (95 % versus 4,24 %) les concentrations obtenues ne permettent pas d'exclure la responsabilité des EBDCs dans l'effet neurotoxique de cette classe de fongicide. Les dosages urinaires effectués chez des viticulteurs en période de traitement de la vigne mettent en évidence une exposition considérable objectivée par une contamination interne malgré les moyens de protection utilisés. Les relations entre l'exposition externe et interne et les mesures de protection restent à étudier sur une large population. Notre travail en a démontré la faisabilitéAn epidemiologic study in Gironde have found an association between long-term exposure to vineyards workers to pesticide and neurologic affections. The ethylene bis dithiocarbamates like Mancozeb are largely used in this district. The EBDCs demonstrate neurotoxicity in animal experiments and epidemiological studies. Occured of Parkinson's disease in subjects expposed a long time to EBDCs has been reported. During the 10 last years, calls to the poisons center of Bordeaux relating to exposure to these fungicides show in 50 % cases of the neurological symptoms. The toxicity of these fungicides is often associated with their common metabolite ethylene thiourea (ETU). The neurotoxicity implies a priori the intracerebral passage or at least in the cerebrospinal fluid (CSF) of the supposed toxins The present study was designed to investigate the metabolism, and CSF penetration of EBDCs and ETU after administration in rats. In this context, we have developed and validated simple methods of detection and quantification of EBDCs and their common metabolite ETU in the various biological matrices. Aproximately 4 % of orally administrated Mancozeb id excreted unchanged in the urines and 4. 9 % is metabolized in ETU, which persists during at least 3 days in the general circulation. Although the diffusion of ETU in the CSF is much higher than that of Mancozèbe (95 % versus 4,24 %) the concentrations obtained do not exclude the responsability of EBDCs in the neurotoxic effect of this class of fungicide. The urinary excretion studied in vineyards workers during application period show a considerable exposure, objectified by an internal contamination in spite of the means of protection used. The relations between external and internal exposure and the means of protection used remain to be studied on a large population. Our work proved the feasibility of such studies
22
Beghidja, Chahrazed. "Complexes mononucléaires et polynucléaires à base de manganèse : Synthèse, études structurales et propriétés magnétiques". Université Louis Pasteur (Strasbourg) (1971-2008), 2005. http://www.theses.fr/2005STR13107.
Texto completo da fonteResumo:
Ce travail de thèse s’inscrit dans le domaine de la cristallochimie organométallique et la magnétochimie de complexes à base de manganèse, susceptibles de présenter des propriétés magnétiques intéressantes. Le travail décrit dans le manuscrit, présente un rappel sur les propriétés magnétiques des 'molécules-aimants' et les conditions nécessaires pour observer de telles propriétés. Une revue détaillée de ce type de molécules citées dans la littérature est présentée également. Les deux techniques de caractérisation utilisées principalement - la détermination de la structure cristalline sur monocristal et les mesures magnétiques - sont présentées avec leurs bases théoriques. Une série de nouveaux complexes mononucléaires à base de manganèse (essentiellement) avec les ligands dérivés du dithiocarbamate, ont été préparés et caractérisés par différentes méthodes spectroscopiques. Ces composés ont fait l’objet d’une étude radiocristallographique détaillée. D’autres complexes polynucléaires à base de manganèse ont été préparés et caractérisés également. Les propriétés magnétiques de ces composés ont été analysées en détail et interprétées compte tenu de leurs structures cristallines. Dans le cas du complexe binucléaire à base de Mn(III), l’étude magnétique détaillée a mis en évidence l’existence d’une forte interaction ferromagnétique avec une constante de couplage la plus élevée dans ce type de composés (J ≈ 20 cm-1). Les résultats obtenus dans cette étude magnétique sont corroborés par des calculs DFT. Les mesures magnétiques réalisées sur le composé pentanucléaire à valence mixte Mn(II)/Mn(III), ont montré que la nature de l’interaction entre les différents ions manganèse est antiferromagnétiqueThis work concerns the organometallic cristalchemistry and the magnetochemistry of complexes containing manganese, which present interesting magnetic properties. The magnetic properties of the ' single-molecule magnet' and the conditions necessary to observe such properties are presented in this manuscript. A detailed review of this molecules quoted in the literature is also presented. The two techniques of characterization used mainly –X-ray single crystals structure determination and magnetic measurements - are presented with their theoretical bases. A new series of mononuclear manganese complexes with a dithiocarbamate derived ligands are prepared and fully characterized by spectroscopic methods and a detailed single crystal X-ray diffraction. Other polynuclear complexes containing manganese were also prepared and characterized. The magnetic properties of these compounds were analyzed in detail and were interpreted taking into account their crystal structures. In the case of the binuclear complex containing Mn(III), the detailed magnetic study indicates the existence of a strong ferromagnetic interaction with the highest coupling constant in this type of compounds (J ≈ 20 cm-1). The results obtained in this magnetic study are corroborated by DFT calculations. The magnetic measurements for the pentanuclear complex with mixed valence Mn(II)/Mn(III), is indicative of the presence of dominant antiferromagnetic interactions between the various manganese ions
23
Franco, Junior Jorge de Oliveira. "Pré-concentração de metais em matrizes salinas empregando ditiocarbamatos". Instituto de Química, 2003. http://repositorio.ufba.br/ri/handle/ri/20663.
Texto completo da fonteResumo:
Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2016-09-20T14:54:53Z
No. of bitstreams: 1
Teseseg.pdf: 4091406 bytes, checksum: 5c096537a6afa0dc26ceb33ccc3387b7 (MD5)Approved for entry into archive by Vanessa Reis (vanessa.jamile@ufba.br) on 2016-09-20T15:53:19Z (GMT) No. of bitstreams: 1 Teseseg.pdf: 4091406 bytes, checksum: 5c096537a6afa0dc26ceb33ccc3387b7 (MD5)
Made available in DSpace on 2016-09-20T15:53:19Z (GMT). No. of bitstreams: 1 Teseseg.pdf: 4091406 bytes, checksum: 5c096537a6afa0dc26ceb33ccc3387b7 (MD5)
CNPQ
Os ditiocarbamatos (carboditioatos) têm sido muito utilizados em operações de pré-concentração de traços de metais por extração (líquido-líquido ou em fase sólida) e co-precipitação. No presente trabalho, apresentam-se os resultados encontrados com a co-precipitação de cobre, níquel, cobalto, chumbo e cádmio empregando piperazina-bis-ditiocarbamato, dietilditiocarbamato e N, N’dibenziletileno bisditiocarbamato sob a forma de compostos do zinco(II). Os reagentes foram preparados a partir da reação entre uma solução da amina correspondente, dissolvida em etanol, alcalinizada com NaOH e resfriada a 10OC com o dissulfeto de carbono (CS2). O precipitado que se forma é separado por filtração e pode ser usado como solução aquosa 1% (m/v) e pode ser conservado por mais de 15 dias. O zinco (II) reage com os ditiocarbamatos de sódio correspondentes e precipita, arrastando os demais metais. O procedimento pode ser executado com soluções com valores de pH entre 6,0 e 9,5 e não é afetado pela ordem de adição dos reagentes. O tempo de centrifugação para deposição da fase precipitada é de 15-30 minutos com uma rotação de 1000-2000 rpm. A co-precipitação simultânea de Cd, Co, Cu, Ni e Pb em níveis de 0,2 g/mL em alíquotas de 50,0 mL de água é possível empregando esta metodologia. As metodologias desenvolvidas foram aplicadas a amostras de água do mar e soluções salinas sintéticas (NaSO4, KCl, NaCl, Na2CO3). Os resultados mostram recuperações superiores a 90% para os metais, exceto para cobalto que tem recuperação superior a 90% apenas quando é empregada a ZnPDC como reagente em soluções salinas 1% (m/v). O método apresentou boa reprodutibilidade e tempo de análise de aproximadamente 4 horas. A metodologia com ZnPDC foi mais precisa para Co e Cu do que as outras metodologias. Sendo o ZnDDC o menos preciso para estes dois metais. Foram realizados experimentos com suporte sólido (naftaleno impregnado com ZnDDC) para a extração de Cd, Co, Cu, Ni e Pb.
The dithiocarbamates (carbodithioates) have been used in operations of pre-concentration of lines of metals by extraction (liquid-liquid or in solid phase) and co-precipitation. In the present work we presented results found for copper co-precipitation, nickel, cobalt, lead and cadmium using the zinc(II) compounds of piperazine-bis-dithiocarbamate, diethildithiocarbamate and N, N' dibenzylethylene bisdithiocarbamate. The reagents were prepared starting from the reaction among a solution of the corresponding amine dissolved in ethanol, alcalized with NaOH and caught a cold to 10O C, with the dissulfide of carbon (CS2). The precipitate that it forms was separated by filtration. The reagent is used as aqueous solution 1% (m/v) and it is stable by 15 days. The zinc (II) reacts with the sodium dithiocarbamates corresponding and co-precipitating with the other metals. The procedure can be executed with solutions with pH values between 4.0 and 10.0, and it is not affected by the order of addition of the reagents. The time of centrifugation is of 15-30 minutes with a rotation of 1000-2000 rpm. A simultaneous co-precipitation of Cd, Co, Cu, Ni and Pb in levels of 0.2 µg/mL in aliquots of 50.0 mL of water are possible using this methodology. The developed methodologies were applied the samples of water of the sea and synthetically saline solution s (NaSO4, KCl, NaCl, Na2CO3). The results show recoveries up to 90%, except for cobalt that has recovery around 90% only when the ZnPDC was used as reagent in saline solutions 1%. The method showed god reproducibility and the time’s analysis during around four hours. The methodology using ZnPDC was more precise to Co and Cu than the others methodologies. The ZnDDC was the less precise for these two metals. We also used a solid support (naphtalene impregnated with ZnDDC) for the extraction of Cd, Co, Cu, Ni and Pb.
24
Cereser, Catherine. "Mécanismes de la cytotoxicité du thirame (disulfure de tétraméthylthiurame) vis à vis des fibroblastes cutanés humains : consommation du glutathion, processus péroxydatifs et blocage de thiol-enzymes". Lyon 1, 2002. http://www.theses.fr/2002LYO1T002.
Texto completo da fonteResumo:
La 4e de couverture indique : "Malgré une large utilisation du thirame depuis les années 1930 comme fongicide et comme accélérateur de vulcanisation, les données concernant sa toxicité sont limitées et peu d'études se sont intéressées à l'action du thirame au niveau cellulaire et subcellulaire. En utilisant le fibroblaste cutané humain en culture comme modèle expérimental, nous avons cherché à évaluer la toxicité cellulaire du thirame et à déterminer son mécanisme d'action toxique par une approche cytochimique. Le thirame entraîne une réduction dose- et temps-dépendante de la viabilité cellulaire conduisant à une mort cellulaire de type nécrotique. Au niveau biochimique, l'action toxique du thirame se traduit d'abord par une diminution rapide de la concentration intracellulaire du GSH suite à une réaction d'oxydo-réduction entre le thirame et le GSH. Cette réaction s'accompagne de la formation de diméthyldithiocarbamate et de GSSG. La disparition du GSH intracellulaire entraîne l'apparition de processus oxydatifs mis en évidence par l'augmentation de la production de TBARS. Le thirame provoque également une diminution de l'activité glutathion réductase et une augmentation de la production de lactate qui reflète une perturbation du métabolisme énergétique cellulaire. Ces deux actions peuvent s'expliquer par la fixation du diméthyldithiocarbamate au niveau des groupements thiols de la glutathion réductase et de certaines enzymes du cycle de Krebs ou de la chaîne respiratoire. Ainsi, le thirame, par des actions directes et indirectes via le diméthyldithiocarbamate, entraîne une altération profonde du métabolisme cellulaire qui aboutit finalement à la mort des cellules. "
25
Salvarese, Nicola. "Synthesis and biological evaluation of Technetium(III)-based radiopharmaceuticals". Doctoral thesis, Università degli studi di Padova, 2012. http://hdl.handle.net/11577/3422151.
Texto completo da fonteResumo:
Development of new 99mTc and 186/188Re radiopharmaceuticals still remain an interesting research topic because of their almost ideal nuclear properties. 99mTc is the radioisotope of election for SPECT‐imaging (Eγ=140 keV, t1/2=6.02 h), while 186/188Re are radionuclides with
an important therapeutic potential (186Re: Eβ‐=1.07 MeV, Eγ=137 keV, t1/2=90.6 h; 188Re: Eβ‐ =2.12 MeV, Eγ=155 keV, t1/2=17 h). Compounds of both Tc and Re in the 3+ oxidation state are well known, however, the chemistry of Tc(III) and Re(III) applied to Nuclear Medicine is still relatively unexplored. This study reports the synthesis and evaluation of a new class of stable, mixed hexacoordinated [99mTcIII(PS)2(L)] complexes, where PS is a phosphinothiolate, and L is a dithiocarbamate. The asymmetric structure potentially allow a fine tuning of the biological and pharmacokinetical behavior of the final compounds through appropriate chemical modifications of the ligands; derivatizations of L can also be conjugated with a biologically active molecule in order to obtain target‐specific radiolabeled compounds. A series of model complexes where M=Re,99gTc and PS=(diphenylphosphino)ethanethiolate (PS2) or 2‐(diisopropylphosphino)ethanethiolate (PSiso) were firstly prepared and characterized. Then, four analogues 99mTc‐radiolabeled complexes are prepared and biologically evaluated.Lo sviluppo di nuovi radiofarmaci a base di Tecnezio‐99m e Renio 186/188 è ancora un campo attuale di ricerca, viste le caratteristiche ideali che questi radionuclidi presentano per l’imaging Medico Nucleare e per la Radioterapia. Lo stato di ossidazione 3+ rappresenta uno dei più comuni e stabili stati di ossidazione del Renio e del Tecnezio. Tuttavia la chimica del Tc(III) e del Re(III) applicata alla Medicina Nucleare continua ad essere poco esplorata. Ciò è dovuto al fatto che la preparazione di tali complessi è generalmente condotta in solventi non acquosi e di conseguenza difficilmente applicabile alla produzione di radiofarmaci in condizioni idonee alla somministrazione nell’uomo. Gli unici esempi di agenti utilizzati in pratica clinica sono il 99mTc‐Teboroxime (un complesso della classe BATO che era utilizzato per l’imaging cardiaco), e il complesso [99mTc(HIDA)2]‐, tutt’oggi utilizzato per l’imaging della funzionalità epatobiliare (HIDA Scan). Questo studio presenta la sintesi e la caratterizzazione di una nuova classe di composti del tecnezio e del renio allo stato di ossidazione III, aventi formula generale [MIII(PS)2(L)], dove PS = fosfinotiolato e L = ditiocarbammato. E’ stato effettuato dapprima uno studio a livello “macroscopico”, di sintesi e caratterizzazione di complessi con gli isotopi 185/187Re e 99gTc. Quindi, quattro analoghi radiocomplessi a base di 99mTc sono stati preparati e valutati nella loro stabilità e nel comportamento biodistributivo in ratti Sprague‐Dawley sani.
26
Mve, Ondo Benjamin. "Oxydation chimique de dithiocarbamates métalliques obtention de degrés d'oxydation élevés non usuels Cuivre (III), Nickel (III) et (IV), Cobalt (IV), Fer (IV) et Manganèse (IV)". Grenoble : ANRT, 1985. http://catalogue.bnf.fr/ark:/12148/cb37594999d.
Texto completo da fonte
27
Segnini, Aline. ""Uso de pirrolidinoditiocarbamatos de manganês(II) e vanadila na preparação e aplicação de eletrodos de pasta de carbono modificados"". Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/75/75132/tde-02102004-121100/.
Texto completo da fonteResumo:
Devido à sua baixa solubilidade em água, os pirrolidinoditiocarbamatos poderiam produzir eletrodos livres do problema de lixiviação do modificador, os quais poderiam ser usados como detectores amperométricos, em análises em fluxo e outros procedimentos hidrodinâmicos. O complexo poderia agir como um intermediário de transferência de elétrons entre o analito e a superfície eletródica, aumentando a sensibilidade da resposta analítica do sensor. Desta forma, eletrodos de pasta de carbono modificados (EPCM) com complexos de pirrolidinoditiocarbamatos anidros de diversos metais foram preparados e testados quanto à sua aplicação em técnicas voltamétricas. Os complexos de manganês(II), [MnPyr2] e cobalto(II), [CoPyr2], foram os que apresentaram os melhores resultados em termos de estabilidade e reprodutibilidade de resposta, escolhendo-se o EPCM-[MnPyr2], para uso neste trabalho. O desempenho do eletrodo foi avaliado usando voltametria cíclica, cronoamperometria e análise em fluxo, com detecção amperométrica de peróxido de hidrogênio apresentando regiões lineares de 1,25-14,8; 0,5-41; 1,0-75 x 10-4 mol L-1 e limites de detecção de 11,2; 2,98; 5,40 x 10-5 mol L-1 respectivamente para cada técnica. Na determinação de peróxido de hidrogênio em amostra de alvejante comercial observou-se concordância nos resultados obtidos em voltametria cíclica e análise em fluxo, usando o eletrodo proposto em comparação com a permanganometria clássica, com 95 % de intervalo de confiança. Estes resultados foram obtidos após otimização de parâmetros como velocidade de varredura, pH, eletrólito suporte, entre outros. A oxidação ocorre por meio de um processo eletrocatalítico. O desempenho do pirrolidinoditiocarbamato de vanadila hidratado também foi avaliado como alternativa aos ditiocarbamatos anidros, na preparação de eletrodos modificados com esta classe de complexos, considerando que os complexos hidratados seriam mais fáceis de preparar. Entretanto uma baixa estabilidade e reprodutibilidade de resposta foi observada. O [MnPyr2] mostrou comportamento no qual ocorre oxidação, concordando com a proposta de Schrauzer para ligantes do tipo ímpar, apesar de que a oxidação só ocorreu na presença de oxidantes fortes, como o peróxido de hidrogênio.Considering their low solubility in water, the dithiocarbamate complexes should produce electrodes without problems of modifier leaching. Such electrodes could be used as amperometric detectors in flow injection analysis and hydrodynamic methods. The complex should act as an electron transfer mediator between the analyte and the electrode surface, improving the response sensitivity of the sensor. Considering these statements carbon paste electrodes modified (EPCM) with anhydrous pyrrolidinedithiocarbamates of several metals were prepared and evaluated in relation to their possible application in voltammetric techniques. Best results regarding response stability and reproducibility were obtained with manganese(II), [MnPyr2] and cobalt(II), [CoPyr2] complexes. The first one was chosen to develop the present work. The electrode performance was evaluated in cyclic voltammetry, chrono amperometric and flow injection analysis with amperometric detection. Linear dynamic ranges of 1,25-14,8; 0,5-41; 1,0-75 x 10-4 mol L-1 and limits of detection of 11,2; 2,98; 5,40 x 10-5 mol L-1 were found respectively for each technique in the determination of hydrogen peroxyde. The methods were used for the determination of H2O2 in bleaching formulation and presented agreement with the classical titration with potassium permanganate within 95% confidence level. Such results have been obtained after optimization of experimental parameters such as scan rate, pH, supporting electrolyte, and others. The oxidation occurred by an electrocatalytic process. Finally the performance of a carbon paste electrode modified with a hydrated vanadyl pyrrolidinedithiocarbamate complex was evaluated as an alternative to the anhydrous complex in the preparation of the modified electrode, since the hydrated complexes are easier to prepare. However a low response stability and reproducibility have been observed. The [MnPyr2] presented an oxidation behavior in agreement with Schrauzers predictions, although the oxidation of the metal center occurred only in the presence of strong oxidative agents as the hydrogen peroxide.
28
Landgraff, Ana Carolina Mafud. "Estrutura cristalina e molecular de derivados de ditiocarbamatos". Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/75/75131/tde-15092006-163541/.
Texto completo da fonteResumo:
A parte intodutória deste trabalho descreve os conceitos básicos da teoria de determminação de estruturas cristalinas, além de alguns aspéctos de ditiocarbamatos. Na parte experimental estão descritas as estruturas cristalinas e moleculares de quatro compostos: Morfolinoditiocarbamato de potássio monoidratado: Sistema cristalino monoclínico; grupo espacial P21/c; Z=4; a=6,723(5); b=17,260(4); c=8,190(8) Å; Beta =108,99(1)0; V=898,7(3) Å3; D=1,621 Mg/m3. O índice de discordância é R(F)=0,0472 (R (F)*= 0,1064 para todas as reflexões), com S=1,012 para 1615 reflexões observadas com I > ou = 2 gama(I) e 107 parâmetros refinados. Morfolinoditiocarbamato de Morfolina: Sistema cristalino monoclínico; grupo espacial P21/c; Z=4; a=7,938(5); b=18,323(1); c=8,826(5) Å; Beta =110,21(5)0; V=1206,16(25) Å3; D=1,381 Mg/m3. O índice de discordância é R(F)= 0,0505 (R (F)*= 0,1273para todas as reflexões), com S=0,997 para 2021 reflexões observadas com I > ou = 2 gama(I) e 191 parâmetros refinados. Morfolinoditiocarbamato de Amônio: Sistema cristalino monoclínico; grupo espacial P21/a; Z=4; a=8,881(9); b=9,002(9); c=11,889(5) Å; beta =104,318(5) 0; V=921,85(12) Å3; D=1,30 Mg/m3. O índice de discordância é R(F)= 0,0557 (R (F)*= 0,0731 para todas as reflexões), com S=1,053 para 2093 reflexões observadas com I > ou = 2 gama(I) e 141 parâmetros refinados. 1-Piperidinoditiocarbamato de Piperidina: Sistema cristalino monoclínico; grupo espacial P21; Z=8; a=12,397(7); b=15,470(1); c=14,320(5) Å; beta =93,326(5)0; V=2741,99(9) Å3; D=1,191 Mg/m3. O índice de discordância é R(F)= 0,0541 (R (F)*= 0,1809 para todas as reflexões), com S=0,974 para 3850 reflexões observadas com I > ou = 2 gama(I) e 542 parâmetros refinados.The first part of this work is a brief description of basics concepts of X ray for a structure solution and some concepts of dithiocarbamates. The experimental part contains the crystal and molecular structure for four compounds and its supramolecular interactions. Potassium Morfolinodithiocarbamate: monoclinic system; space group P21/c; Z=4; a=6.723(5); b=17.260(4); c=8.190(8) Å; b=108.9(1)0; V=898.7(3) Å3; D=1.621 Mg/m3; 1615 observed reflections (I ³ 2s(I)); NPAR=107. The final disagreement indices are: R(F)=0.0472. R (F)*= 0.1064; S=1.012. Morfoline Morfolinodithiocarbamate: monoclinic system; space group P21/c; Z=4; a=7.938(5); b=18.323(1); c=8.826(5) Å; b=110.2(5)0; V=1206.16(25) Å3; D=1.381 Mg/m3; 2021 observed reflections (I ³ 2s(I)); NPAR=191. The final disagreement indices are: R(F)= 0.0505; R(F)*=0.1273; S=0.997. Amonium Morfolinodithiocarbamate: monoclinic system; space group P21/a; Z=4; a=8.881(9); b=9.002(9); c=11.889(5) Å; b=104.3(5) 0; V=921.85(12) Å3; D=1.30 Mg/m3; 2093 observed reflections (I ³ 2s(I)); NPAR=141. The final disagreement indices are: R(F)= 0.0557; R(F)*=0.0731; S=1.053. Piperidiniun 1-Piperidinodithiocarbamate: monoclinic system; space group P21; Z=8; a =12.397(7); b=15.470(1); c=14.320(5) Å; b=93.326(5)0; V=2741.99(9) Å3; D=1.191 Mg/m3; 3850 observed reflections (I ³ 2s(I)); NPAR=542. The final disagreement indices are: R(F)= 0.0541; R(F)*= 0.1809; S=0.974.
29
Vareli, Catiuscia Souza. "Desenvolvimento e validação de método para determinação de etilenotiouréia em urina empregando HPLC UV". Universidade Federal de Santa Maria, 2008. http://repositorio.ufsm.br/handle/1/10425.
Texto completo da fonteResumo:
In order to supply the world-wilde demand for food, it is essential to use the pesticides to protect the crops against pests and diseases. But the indiscriminate and injudicious use of these compounds have resulted in widespread contamination in food commodities and environment in all fields, increasing, this way, the preoccupation with chemical products use. Ethylene-bis-dithiocarbamate pesticides,
from dithiocarbamate class, are among the most widely used fungicide to control pest. Beside their low toxicity, one of they degradation products, ethylenethiourea, is
a toxic metabolite, which have teratogenic, carcinogenic, immunotoxic and mutagenic effects. In the present work, it was developed and validated a chromatographic
method for the determination of ethylenethiourea (ETU) residues in urine, using liquid-liquid extraction and HPLC quantification. The developed procedure consist of
the interested compound extraction from urine, with 6.0 mL of dichloromethane, aditioning MgSO4 to help in the partitioning process, that is, distribution os compound between organic and aqueous phase. After sample centrifugation, a
supernatant aliquot was taken and evaporated, in water bath at 44 ºC, and the final extract was redissolved in purified water and analyzed by HPLC-UV, injecting 50 μL
in C18 column with mobile phase MeOH:H2O (10:90; v/v) and detection by UV light absorption at 233 nm. To the validation study of the method, the following parameters were
evaluated: detection limit (LOD), quantification limit (LOQ), precision (under repeatability and reproducibility conditions) and accuracy as recovery. The method LOD was 0.05 mg ETU L-1 and LOQ was 0.2 mg ETU L-1. The analytical curve was
linear between 0.05 to 1.0 mg ETU L-1 with determination coefficient r2 > 0.998. Very good precision with RSD between 1.7 and 2.7% was obtained and the recoveries ranged from 85.6 to 95.4% for 3 different spike level: 0,05, 0,1 and 0,5 mg ETU L-1 . The results obtained in the validation step allow us to conclude that the method are quite appropriate to determine residue of ethylenethiourea in urine. The
developed method has shown advantages, such as simplicity, quickness and that it could be applied in any laboratory. However, there are some points such as no ETU confirmation nether purity analysis of the chromatographic picks besides the low sensitivity and selectivity of the UV detection that would be much improved using a LC-MS/MS.Para atender a demanda mundial por alimentos, é essencial o emprego de pesticidas para proteger as culturas contra doenças e pragas, mas o uso imprudente e indiscriminado destes compostos pode resultar em contaminação dos alimentos e seus derivados, bem como no ambiente como um todo, aumentando, dessa forma, a preocupação em relação ao emprego dos pesticidas. Os pesticidas etileno-bisditiocarbamatos, da classe dos ditiocarbamatos, estão entre os fungicidas mais empregados em todo o mundo para o controle de pragas. Apesar de possuírem baixa toxicidade, um de seus produtos de degradação, a etilenotiouréia (ETU), é um metabólito tóxico, a qual possui efeitos teratogênicos, carcinogênicos, imunotóxicos e mutagênicos. Neste trabalho, desenvolveu-se e validou-se um método cromatográfico para a determinação dos resíduos de ETU em urina, empregando-se extração líquidolíquido e quantificação por HPLC-UV. O procedimento desenvolvido consiste na extração do analito de interesse, com 6 mL de diclorometano, adicionando-se MgSO4 para auxiliar no processo de partição, ou seja, distribuição do composto entre as fases orgânica e aquosa. Posteriormente, centrifugou-se e evaporou-se uma alíquota do sobrenadante em banho de água à 44 ºC, redissolvendo-se em água purificada e analisa-se em sistema HPLC, injetando-se 50 μL em coluna C18 com fase móvel MeOH:H2O (10:90; v/v) e detecção por absorção de luz em 233 nm. Para a validação do método avaliaram-se os seguintes parâmetros: limite de detecção (LOD), limite de quantificação (LOQ), linearidade, precisão (repetitividade e precisão intermediária) e exatidão (recuperação). O LOD do método foi de 0,05 mg ETU L-1 e o LOQ 0,2 mg ETU L-1. As curvas analíticas apresentaram r2 > 0,998 com linearidade entre 0,05 e 1,0 mg ETU L-1. Os resultados de precisão foram excelentes, com valores de desvio padrão relativo entre 1,7 e 2,7%, e as recuperações foram de 85,6 a 95,4% para 3 níveis de fortificação: 0,05, 0,1 e 0,5 mg ETU L-1. Através dos resultados obtidos na validação, pode-se concluir que o método é apropriado para determinar resíduos de etilenotiouréia em urina. O método tem várias vantagens como: simplicidade, rapidez, e poder ser executado com equipamentos geralmente disponíveis nos laboratórios. Entretanto, poderia apresentar resultados ainda melhores em termos de sensibilidade, seletividade e confirmação da identidade da ETU, se fosse possível, por exemplo, a utilização de cromatógrafo à líquido acoplado à espectrômetro de massas, onde a pureza dos picos cromatográficos poderia ser avaliada e a detectabilidade poderia ser 3 ordens de magnitude menor (1000 vezes).
30
ALVES, Márcia Regina Ribeiro. "Efeito de soluções de enxágüe na remoção de resíduos de mancozeb em tomates". Universidade Federal de Goiás, 2008. http://repositorio.bc.ufg.br/tede/handle/tde/1452.
Texto completo da fonteResumo:
Made available in DSpace on 2014-07-29T15:22:58Z (GMT). No. of bitstreams: 1
marcia regina ribeiro alves.pdf: 452897 bytes, checksum: 176d4d065ab6a2068b7a4fde3b142306 (MD5)
Previous issue date: 2008-05-08Fungicides are the pesticides mostly used the tomato crop. Among the fungicides the dithiocarbamates are the mostly used. The objective of this work was to study the efficiency of the dithiocarbamate mancozeb removal from tomatoes through processes of washes. We performed analyses of acidity, brix, the activity of water (aw), pH and content of manganese for tomatoes. After completing the procedures of the fruit flush with tap water, vinegar, alcohol, and sodium bicarbonate solution of sodium dichloroisocyanurate dihydrate the level of the fungicide mancozeb was assessed in skin and whole fruit. It was observed that the process of the fruit flush significantly reduces the amount of residues in tomatoes. The reduction of mancozeb was higher in the skin, which are present in highest concentration. The treatments using tap water and sodium bicarbonate removed over 61% of the residue present in the skin of tomatoes
Dentre os agrotóxicos mais utilizados na cultura do tomate estão os fungicidas e, dentre estes, os mais aplicados na cultura são os ditiocarbamatos. O objetivo deste trabalho foi estudar a eficiência da remoção do ditiocarbamato mancozeb em tomates através de processos de enxágüe. Foram realizadas análises de acidez, brix, da atividade de água (aw), pH e teor do manganês para os tomates. Após realização do processos de enxágüe do fruto com água de torneira, vinagre de álcool, bicarbonato de sódio e solução de dicloroisocianurato de sódio dihidratado foi avaliado o teor do fungicida mancozeb na película e fruto inteiro. Observou-se que o processo de enxágüe do fruto reduz significativamente a quantidade resíduos nos tomates. A redução de mancozeb foi maior na película, onde estão presentes em maior concentração. Os tratamentos usando água de torneira e bicarbonato de sódio removeram acima de 61% dos resíduos presentes na película dos tomates
31
Al-Alam, Joséphine. "Polluants organiques : analyse, application au « biomonitoring » environnemental et introduction des biopesticides (algues marines) comme alternative". Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF019.
Texto completo da fonteResumo:
Dans un contexte où les inquiétudes environnementales dues à la pollution sont grandissantes à l’échelle globale, la surveillance de la pollution environnementale constitue un enjeu majeur de recherche afin de préserver au mieux un environnement sain et durable. En effet, la surveillance responsable et continue de l’environnement accompagnée par le développement d’alternatives de lutte « verte » contre les nuisibles, pourrait certainement ralentir voir inhiber la propagation de polluants néfastes pour l’ensemble de la biosphère. Dans ce contexte, les objectifs principaux de cette thèse visent d’une part à caractériser la qualité de l’air par une approche basée sur le biomonitoring, et d’autre part à développer un biopesticide d’origine algale permettant la protection des agrumes en post-récolte comme un exemple d’alternative à l’usage des traitements chimiques classiques. Pour répondre au premier objectif, des méthodes d’extraction multi résidus ont dû être développées. Ces méthodes ont été soit spécifiques d’une famille de pesticides tel que les dithiocarbamates, soit plus large et plus générale en considérant de nombreux polluants comme des pesticides, des HAPs et des PCBs. Ces dernières ont été basées soit sur l’ASE-SPE-SPME, soit sur le QuEChERS-SPME, et ont formé le socle des études de biosurveillance environnementale entreprises. Ces études de surveillance ont permis l’évaluation des modifications spatio-temporelles de la qualité de l’air grâce à des espèces naturelles ayant un rôle de capteurs biologique de la pollution environnementale et permettant par la suite l’estimation de la pollution dans des zones bien définies. Pour répondre au second objectif, des extraits aqueux d’algues vertes, Ulva linza et Ulva lactuca, ont été préparés et testés comme antifongiques in vivo et in vitro afin d’étudier leur aptitude à inhiber le développement de Penicillium digitatum sur des agrumes en post récolte. Un potentiel de protection des agrumes en poste-récolte contre ce champignon a été mis en évidence, donnant effectivement l’espoir à la fiabilité de cette approche comme alternative biologique pour le remplacement des pesticides chimiques potentiellement toxiquesIn a context where environmental concerns due to pollution are growing on a global scale, monitoring of environmental pollution is a major research challenge in order to preserve as much as possible a healthy and sustainable environment. Indeed, the responsible and continuous monitoring of the environment escorted by the development of "green" pest control alternatives could certainly decelerate or even inhibit the spread of harmful pollutants into the entire biosphere. In this context, the main objectives of this thesis are intended firstly to characterize air quality by a biomonitoring-based approach and, secondly, to develop a biopesticide of algal origin, that allows the protection of post-harvested citrus fruit, as an alternative to the use of conventional chemical treatments. In order to answer the first objective, multi-residues extraction methods were developed. These methods were either specific to a family of pesticides such as dithiocarbamates or wider and more general regarding numerous pollutants such as pesticides, PAHs and PCBs. The latter were based either on the ASE-SPE-SPME, or on the QuEChERS-SPME, and formed the base of environmental biomonitoring studies undertaken. These monitoring studies allowed the assessment of spatial and temporal changes in air quality through natural species acting as biological sensors of environmental pollution and subsequently allowing the estimation of pollution in well-defined areas. To answer the second objective aqueous extracts of green algae, Ulva linza and Ulva lactuca, were prepared and tested as in vivo and in vitro antifungal agents, in order to study their ability to inhibit the development of Penicillium digitatum on post-harvested citrus fruits. A potential of post-harvested citrus fruits’ protection against this fungus was proved, giving hope to the reliability of this approach as a biological alternative for the replacement of potentially toxic chemical pesticides
32
Gowda, V. (Vasantha). "Experimental and computational magnetic resonance studies of selected rare earth and bismuth complexes". Doctoral thesis, Luleå University of Technology, 2017. http://jultika.oulu.fi/Record/isbn978-91-7583-948-6.
Texto completo da fonteResumo:
Abstract
The rare-earth elements (REEs) and bismuth, being classified as the ‘most critical raw materials’ (European Raw Materials Initiatives, 2017), have a high economic importance to the EU combined with a high relative supply risk. REEs are highly important for the evolving technologies such as clean-energy applications, high-technology components, rechargeable batteries, permanent magnets, electric and hybrid vehicles, and phosphors monitors.
This scientific research work aims at building a fundamental knowledge base concerning the electronic/molecular structure and properties of rare-earth element (REE) and bismuth complexes with dithiocarbamate (DTC) and 1,10-phenanthroline (PHEN) by employing state-of-the-art experimental techniques such as nuclear magnetic resonance (NMR) spectroscopy and X-ray diffraction (XRD) techniques together with ab initio quantum mechanical computational methods. This combination of methods has played a vital role in analysing the direct and significant effect of the heavy metal ions on the structural and magnetic resonance properties of the complexes, thereby, providing a framework of structure elucidation. This is of special importance for REEs, which are known to exhibit similar chemical and physical properties. The objectives of the work involve i) a systematic investigation of series of REE(III) as well as bismuth(III) complexes to get a profound understanding of the structure-properties relationship and ii) to find an appropriate theoretical modelling and NMR calculation methods, especially, for heavy metal systems in molecular and/or solid-state. This information can later be used in surface interaction studies of REE/bismuth minerals with DTC as well as in design and development of novel ligands for extraction/separation of metal ions.
The REE(III) and bismuth(III) complexes with DTC and PHEN ligands have all provided a unique NMR fingerprint of the metal centre both in liquid and solid phase. The solid-state ¹³C and ¹⁵N NMR spectra of the diamagnetic REE(III) and bismuth(III) complexes were in accord with their structural data obtained by single crystal XRD. The density functional theory (DFT) methods were used to get complementary and refined structural and NMR parameters information for all diamagnetic complexes in the solid-state. The relativistic contributions due to scalar and spin-orbit correlations for the calculated ¹H/¹³C/¹⁵N chemical shifts of REE complexes were analysed using two-component zeroth-order regular approximation (ZORA)/DFT while the ‘crystal-lattice’ effects on the NMR parameters were calculated by combining DFT calculations on molecular and periodic solid-state models. The paramagnetic REE complexes display huge differences in their ¹H and ¹³C NMR spectral patterns. The experimental paramagnetic NMR (pNMR) chemical shifts, as well as the sizable difference of the ¹H and ¹³C NMR shifts for these isoelectronic complexes, are well reproduced by the advanced calculations using ab initio/DFT approach. The accuracy of this approach is very promising for further applications to demanding pNMR problems involving paramagnetic f-block elements.
The results presented in this thesis demonstrate that a multidisciplinary approach of combined experimental NMR and XRD techniques along with computational modelling and property calculations is highly efficient in studying molecular complexes and solids containing heavy metal systems, such as rare-earths and bismuth.
33
Tzanis, Lydie. "Réactivité de silices fonctionnalisées par des groupements dithiocarbamates vis-à-vis de Co(II) et Ni(II) : vers une nouvelle méthode de diagnostic de l'exposition aux métaux lourds lors du recueil des urines". Thesis, Nancy 1, 2008. http://www.theses.fr/2008NAN10098/document.
Texto completo da fonteResumo:
L’objectif principal de la thèse concerne la mise au point d'une méthode de piégeage et d'analyse quantitative de métaux cancérogènes ou susceptibles de l'être dans les urines, en permettant de s'affranchir du transport de l'échantillon sous forme liquide. Parmi les éléments traces métalliques (ETM), nous nous sommes intéressés plus particulièrement aux espèces du cobalt et du nickel. L'approche présentée repose sur l'extraction solide/liquide des ions métalliques par complexation sur des matériaux mésoporeux hybrides organo-minéraux à grande surface spécifique. Les matériaux adsorbant sélectionnés sont des silices fonctionnalisées par des groupements dithiocarbamate. Après avoir préparé ces supports par greffage au moyen de nouveaux précurseurs siloxydithiocarbamate, les matériaux fonctionnels ont été caractérisés par diverses techniques physico-chimiques et leur comportement en solution a été étudié. Il en ressort que les interactions entre ces fonctions dithiocarbamate et la surface de la silice peuvent conduire à une perte des greffons en milieu aqueux surtout pour des séjours prolongés en solution. Néanmoins, ces solides ont pu être exploités avec succès pour l’immobilisation quantitative des espèces CoII et NiII à partir de solutions diluées (de 1 à 500 µg.L-1), et ce dans la gamme de pH susceptible d’être rencontrée en milieu urinaire. Cette étude a nécessité la mise au point d’une méthode analytique de routine pour la détermination simultanée et quantitative de ces éléments en solution. Il s’agit de la chromatographie haute performance pour laquelle les meilleurs résultats ont été obtenus au moyen la technique dite de commutation de colonne. Les opérations d’adsorption se sont révélées être rapides, ce qui a permis d’opérer efficacement lors de la mise en œuvre de cartouches au travers desquelles les échantillons ont été percolés. Des efforts ont également été consentis de manière à définir les conditions optimales de désorption en vue de l’analyse quantitative des analytes précédemment accumulésThe main object of the thesis concerns the development of a trapping method for quantitative analysis of carcinogenic - or likely to be - metal ions in urine, allowing to avoid sample transport in a liquid form. Among the metal ions a trace levels, we have been particularly interested in cobalt and nickel species. The approach presented here is based on solid/liquid extraction of metal ions by complexation on mesoporous organic-inorganic hybrid materials with large specific surface areas. The selected adsorbents are silica gels functionalised with dithiocarbamate groups. After their preparation by post-synthesis grafting using new siloxydithiocarbamate precursors, the functionalized silica gels have been characterized by various physico-chemical techniques and their behaviour in solution has been investigated. It shows that interactions between dithiocarbamate moieties and the silica surface can lead to a loss of grafted groups in the external solution, especially for extended periods in aqueous medium. However, these hybrids have been successfully used for quantitative sequestration of CoII and NiII from dilute solutions (1 to 500 µg L-1), within the pH range likely to be encountered in urinary environment. This study has also involved the development of an analytical method for the simultaneous and quantitative determination of these elements in solution. This was based on high performance liquid chromatography for which the best results were obtained using the switching column technique. Adsorption operations have proven to be very fast, which has allowed operating effectively in the implementation of cartridges through which the samples have been percolated. Efforts have also been made to define the optimal conditions for desorption, which was then applied to the quantitative analysis of analytes previously accumulated in the cartridge
34
Forster, Glyn Daniel. "Dithiocarbamate stabilised molybdenum imido complexes". Thesis, University College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261809.
Texto completo da fonte
35
Cookson, James. "Supramolecular chemistry using the dithiocarbamate ligand". Thesis, University of Oxford, 2004. https://ora.ox.ac.uk/objects/uuid:88c7067e-37c8-4144-b8ee-dfe7003cb0b6.
Texto completo da fonte
36
Silva, Rosselei Caiél da. "Métodos individual e multirresidual para determinação de pesticidas em grãos e derivados por GC-PFPD, GC-ITD-MS e LC-MS/MS". Universidade Federal de Santa Maria, 2011. http://repositorio.ufsm.br/handle/1/4212.
Texto completo da fonteResumo:
Conselho Nacional de Desenvolvimento Científico e TecnológicoDue to the complexity of grains like soybean, corn and rice, and the very low pesticide concentration expected for these samples, it is really necessary to develop efficient and reliable analytical methods to identify and quantify their residues. The possibility to perform the determination of a large number of pesticides in just a single chromatographic analysis is the major advantage of the multi-residue methods. However, there are important compounds that are not possible to be analyzed together, like the dithiocarbamates (DTC). For that, is so important to develop and validate single methods. Due to low acute toxicity, combined with strong action, low-cost production and low environmental persistence, the dithiocarbamates are still using worldwide. The first part of this study reports a sensitive analytical single method suitable for the quantitative analysis of DTCs in soybeans, rice and corn, using GC-PFPD and GCITD- MS. For the method validation studies, the following parameters were assessed: detection limit (LOD), quantification limit (LOQ), precision (repeatability and intermediate precision) and accuracy, via recovery experiments at 0.05, 0.1 and 0.5 mg CS2 kg-1 spiking levels. For soybeans is necessary a clean-up step due the high fat content in that crop, because of it, same sorbents (Aluminum oxide, Florisil®, Silica, PSA, C18 and C18OH) were tested and the best results were obtained applying silica gel. For the extraction procedure, an amount of sample was weighed and water added. The spike solution (thiram) was added to the sample, 25 mL of isoctane and 150 mL of tin (II) chloride solution in hydrochloric acid were added. The bottles were closed immediately and heated for 1 h in a water bath at 80 °C, under shaking. After cooling, 2 mL aliquot of the upper organic layer of each bottle was pipetted into a tube containing 50 mg of silica gel, for the clean-up step. The analytical curves were linear from 0.02 to 1.0 mg CS2 L-1 with determination coefficients (r2) higher than 0.99 for both detection systems and to all crops. Method LOD and LOQ values were 20 and 50 μg CS2 kg-1, respectively, for soybeans and corn. For rice LOQ was just 40 μg CS2 kg-1. Very good precision was obtained with RSD between 1.8 and 7.9% and recoveries from 67 to 103%, for all matrices. The results obtained in the validation step allow us to conclude that both chromatographic detection systems are appropriate to determine residues of DTCs in grains. The second step was to develop and validate a method for the analysis of 75 pesticides in corn grain and breakfast cereals using LC-MS/MS, ESI positive mode. The extraction procedure was the modified QuEChERS method, however, excluding the dispersive SPE clean-up step. To that end, milled and homogenized corn grain and breakfast cereals with water were spiked with 75 pesticides, at 3 spiking levels (10, 20 and 50 μg kg-1, n=6), plus the procedure internal standard (quinalfos). A volume of 10 mL of acetonitrile with 1% acetic acid was added and the tubes were vigorously shaken for 1 minute. The tubes were uncapped, anhydrous magnesium sulfate were added, the shaking procedure was repeated and the extract was centrifuged at 4000 rpm, for 4 min. The upper layer of the extracts was transferred to chromatographic vial, containing 0.5 mL of the instrumental internal standard (propoxur) in methanol. The linear range wasevaluated and validated between 0.1 and 50 μg L-1 of the analytical curves (7 concentrations, n=6). Also LOD, LOQ, matrix effect, as well as precision (as RSD%) and accuracy (as recovery), for 75 pesticides, were studied The LOD were calculated based on practically realized repeatability RSD. To determine the precision, accuracy and LOQ, blank samples were spiked at 10, 20 and 50 μg kg-1. The results showed recoveries between 70 and 120% and RSDs <20% for the majority of the pesticides studied, even at the lowest level. As expected, the matrix effect did not have influence on the results, and the values of LOD and r2 were considered as satisfactory for the purpose of this study.
Devido a complexidade de matrizes de grãos como soja, milho e arroz, e das baixas concentrações dos pesticidas presentes, há uma grande necessidade de desenvolvimento de métodos analíticos eficientes e confiáveis para a identificação e quantificação desses resíduos. A maior vantagem de um método multirresidual é a possibilidade de se determinar um grande número de pesticidas na mesma análise cromatográfica. Entretanto, alguns compostos, devido suas características específicas, não podem ser determinados em conjunto com outros analitos. Assim, é importante que também se desenvolva e valide métodos individuais de análise, comoo método para determinação de ditiocarbamatos (DTC). Os DTC apresentam baixa toxicidade aguda, combinado com forte ação fúngica, baixo custo e baixa persistência ambiental, por isto, estes continuam sendo largamente utilizados na agricultura. Na primeira parte deste estudo, foi desenvolvido um método individual de análise para determinar DTC em soja, arroz e milho, empregando GC-PFPD e GC-ITD-MS. Para o estudo de validação do método, os seguintes parâmetros foram avaliados: limite de detecção (LOD), limite de quantificação (LOQ), precisão e exatidão, através do estudo de fortificação e recuperação, nas seguintes concentrações: 0,05; 0,1 e 0,5 mg CS2 kg-1. Para a determinação de ditiocarbamatos, adicionou-se um volume de água à amostra (arroz, milho e soja). Fortificou-se com solução de tiram, adicionou-se 25 mL de isoctano e 150 mL de solução de SnCl2 em HCl. Os frascos foram fechados e levados ao banho de agitação, a 80 °C, por 1 hora. Após o resfriamento, 2 mL da fase orgânica foram transferidos para outro frasco contendo 50 mg de sílica gel, para a etapa de purificação. As curvas analíticas foram lineares na faixa de 0,02 a 1,0 mg CS2 L-1, com coeficiente de determinação (r2) maior do que 0,99, para todas as culturas, nos dois sistemas de detecção. O LOD e LOQ do método apresentaram os mesmos valores para soja e milho, sendo, respectivamente, 20 e 50 μg CS2 kg-1. Já o LOQ para arroz foi de 62 μg CS2 kg-1, devido a menor quantidade de amostra utilizada. Observa-se, desta forma, que os valores de LOQ encontrados são inferiores ao limites máximos de resíduos permitidos (LMR) pela legislação nacional, que são de 0,3 mg CS2 kg-1 para soja e milho, e de 3 mg CS2 kg-1 para o arroz, indicando que os métodos podem ser utilizados para este tipo de determinação. A precisão mostrou-se muita boa, com valores de RSD entre 1,8 e 8,7%, e recuperações de 63 a 103%. Assim, os resultados obtidos pela validação do método permitem concluir que ambos os sistemas cromatográficos são adequados para determinar DTC em grãos. A segunda etapa do estudo foi validar o método multirresidual para determinação de 75 pesticidas em milho (grão) e cereais matinais, empregando LCMS/ MS, no modo ESI positivo. O procedimento de extração foi baseado no método QuEChERS, com algumas modificações. Grãos de milho e cereais matinais foram moídos e homogeneizados, e um volume de água de, respectivamente, 7,5 e 8 mL foi adicionado. Após, executou-se a fortificação com uma solução contendo os 75 pesticidas do estudo, nos níveis de concentração de 10, 20 e 50 μg kg-1. Um volume de 10 mL de solução de ácido acético 1% em acetonitrila contendo o padrão interno quinalfós foi adicionado, e os tubos agitados por 1 minuto. Os tubos foram abertos e MgSO4 anidro adicionado seguido de agitação e centrifugação a 4000 rpm, por 4 minutos. Um volume de 0,5 mL da fase superior foi transferido para vial contendo 0,5 mL do padrão interno propoxur em metanol. Os resultados obtidos para esta validação foram satisfatórios. Recuperações entre 70 e 120%, com RSD <20% foram obtidos para a maioria dos pesticidas estudados, nas duas matrizes, conforme recomendando pela SANCO (2009). Conforme esperado em LC-MS/MS, o efeito matriz não influenciou os resultados.
37
Lepareur, Nicolas. "VECTORISATIONS ACTIVE ET PASSIVE DE RADIOPHARMACEUTIQUES DU TECHNETIUM-99m ET DU RHENIUM-188 POUR L'IMAGERIE MEDICALE ET LA THERAPIE". Phd thesis, Université Rennes 1, 2003. http://tel.archives-ouvertes.fr/tel-00128645.
Texto completo da fonteResumo:
La recherche de nouvelles molécules pour la médecine nucléaire est un domaine en expansion croissante. Ces dernières années, le développement de nouveaux radiopharmaceutiques à visée thérapeutique a relancé l'intérêt pour la chimie du rhénium. En effet, les deux isotopes 186Re et 188Re, du fait de leurs propriétés adéquates et de leur analogie avec le 99mTc, largement utilisé pour les examens cliniques, semblent très prometteurs pour la préparation de radiopharmaceutiques.Dans la première partie de ce manuscrit, la synthèse de complexes du rhénium et du technétium-99, [M(RPhCS3)2(RPhCS2)] (M = Re, Tc), est décrite. La préparation de radiopharmaceutiques à base de technétium-99m, analogues des composés obtenus à l'échelle pondérale, est également décrite. La stabilité/réactivité de ces complexes a été étudiée, au moyen de réactions d'échange avec d'autres ligands potentiels, et notamment par des dithiocarbamates, ainsi que par spectrophotométrie d'absorption UV-visible et analyse thermogravimétrique.
La réactivité des complexes vis-à-vis des dithiocarbamates conduit à la possibilité du greffage de biomolécules sur le cœur métallique, via le fragment dithiocarbamate. Cette méthode constitue une alternative potentielle aux procédures actuelles utilisant l'approche bifonctionnelle.
Dans la seconde partie de ce manuscrit, la mise au point d'un kit pour le marquage du lipiodol par le rhénium-188 est décrite, à partir du complexe analogue des complexes décrits dans la première partie. L'huile radiomarquée ainsi obtenue est potentiellement utilisable pour le traitement de l'hépatocarcinome. La stabilité in vitro et in vivo du complexe rhénié 188Re-SSS lipiodol et de son analogue technétié 99mTc-SSS lipiodol a été étudiée, ainsi que leur comportement in vivo sur un modèle de porc sain.
Cette étude a permis de montrer la fixation quasi-exclusive du radiopharmaceutique au niveau du foie, ainsi que la stabilité de ce composé. Sa sélectivité pour les tumeurs reste à démontrer avant de passer aux premiers essais chez l'homme.
38
Lemes, Vera Regina Rossi. "Avaliação de resíduos de etilenotiouréia (ETU) em frutas comercializadas na cidade de São Paulo". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/6/6134/tde-17042008-163646/.
Texto completo da fonteResumo:
Etilenotiouréia (ETU) é uma substância tóxica, formada pela degradação e/ou biotransformação dos fungicidas etilenobisditiocarbamatos (EBDC). Seus resíduos podem ser encontrados em plantas e no ambiente, após o uso de EBDC na agricultura, ou em animais e no ser humano, quando expostos a esses produtos. Comprovadamente, a ETU tem a capacidade de induzir tumor na tireóide de roedores e no fígado de camundongo, apresentando evidência suficiente para carcinogenicidade em animais e evidência inadequada para carcinogenicidade em seres humanos. Os objetivos deste estudo foram: validar método analítico para determinação de resíduos de ETU nas matrizes estudadas; verificar a presença de resíduos de ETU em amostras de frutas (mamão, maçã e morango), coletadas em diferentes pontos de comercialização da cidade de São Paulo; avaliar os resultados e a contribuição de risco à saúde da população consumidora. Foram analisadas 90 amostras, sendo 30 de cada fruta (maçã, mamão e morango), adquiridas em diferentes pontos de comercialização da cidade São Paulo, no período de dezembro de 2005 a dezembro de 2006, distribuídas nas diferentes regiões do referido município e durante as estações do ano. Os parâmetros de validação avaliados foram: seletividade, linearidade, limite de quantificação, limite de detecção, exatidão e precisão. Os estudos de recuperação foram realizados com fortificações em três níveis (1, 2 e 10 LQ) em amostras controle. A determinação de resíduos de ETU foi feita por cromatografia a líquido de alto desempenho, com detector de absorção no ultravioleta (HPLC-UV) e cromatografia a líquido acoplada à espectrometria de massas em tandem (LC/MS/MS). Como todos os resultados obtidos por HPLC-UV apresentaram níveis de ETU abaixo do LQ limite de quantificação (10,0?g/kg), as quantificações foram realizadas no LC/MS/MS, com limite de quantificação e de detecção respectivamente de 1,0?g/kg e 0,5?g/kg. O método por LC/MS/MS mostrouse adequado para análise de ETU nos níveis de até 2,0?g/kg para maçã e morango e de até 10,0 ?g/kg para mamão, com recuperações médias de 75 a 110% e coeficientes de variação de 6 a 17%. Foram encontrados resíduos de ETU em 10 (33%) das amostras de maçã, em níveis que variaram de 1,0 a 3,7 ?g/kg (ppb); em 20 (67%) das amostras de mamão, de 1,0 a 5, 3?g/kg; em 2 (7%) das amostras de morango, de 1,0 a 1,4 ?g/kg. Estes valores estão abaixo do limite de 50?g/kg, estabelecido na União Européia. A estimativa da ingestão de resíduos de ETU pelo consumo das frutas estudadas, considerando o maior nível encontrado nesta pesquisa e dados fornecidos pelo IBGE, representam respectivamente 0,05 e 0,20 % da IDA (Ingestão Diária Aceitável, estabelecida pelo Codex Alimentarius), para a população em geral e crianças. A estimativa da ingestão de resíduos de EBDC pelo consumo dos alimentos (maçã, tomate, mamão, alface, morango, banana, laranja, cenoura), monitorados pelo PARA no período de 2001 a 2004, considerando os maiores níveis encontrados e 100% dos resíduos de ditiocarbamatos (CS2) como sendo originários do uso de EBDC, foi de 7,2% para a população em geral e de 28,9 % para crianças. Dados de ETU e EBDC em outros alimentos, incluindo os industrializados, em água de consumo e em amostras ambientais, além de dados mais refinados de consumo alimentar para subgrupos mais sensíveis (como crianças e mulheres grávidas), são necessários para se avaliar o risco de maneira mais global e condizente com a realidade, em prol da Saúde Pública.Ethylene thiourea (ETU) is a toxic substance generated by the degradation and/or biotransformation of ethylenebisdithiocarbamates (EBDC) fungicides. Their residues may be found in plants and in the environment after EBDC's use in agriculture or in animals and humans when exposed to such products. ETU is confirmedly able to induce tumors in rodents' thyroids and in mouse's liver, showing enough evidence of carcinogenicity in animals and inadequate evidence of carcinogenicity in humans. The aims of this study were validating an analytical method for determining ETU residues in the studied sources, verifying the presence of ETU residues in fruit samples (papaya, apple and strawberry) collected from different commercial centers in the city of São Paulo; evaluating the results and their contribution as a risk to the consumers' health. Ninety fruit samples (30 samples of each fruit - papaya, apple and strawberry) were analyzed. The samples were purchased at different commercial centers in different regions of the city of São Paulo and over all seasons during December 2005 through December 2006. The validation parameters used were selectivity, linearity, accuracy and precision. Recovery studies were carried out with fortifications in 3 levels (1, 2 and 10 times the Limit of Quantification, LQ) in control samples. The determination of ETU residues was carried out by high performance liquid chromatography, ultra-violet absorption detector (HPLC/UV) and liquid chromatography coupled on tandem mass spectrophotometry (LC/MS/MS). Since all results obtained through HPLC/UV showed levels of ETU below the LQ (10.0 ?g/kg), quantification were carried out through LC/MS/MS with quantification and detection limits of 1.0?g/kg and 0.5 ?g/kg, respectively. The LC/MS/MS method proved adequate for analyzing quantities of ETU as low as 2.0 ?g/kg in apple and strawberry and 10.0 ?g/kg in papaya, with average recovery of 75 to 110 % and variation coefficients of 6 to 17 %. ETU residues were found in 10 (33%) apple samples with levels ranging from 1.0 to 3.7 ?g/kg (ppb); in 20 (67%) of papaya samples with levels ranging from 1.0 to 5.3 ?g/kg (ppb); and in 2 (7%) strawberry samples with levels ranging from 1.0 to 1.4 ?g/kg (ppb). These values are below the limit established in European Community (50 ?g/kg). The assessment of ETU intake, considering the consumption informed by IBGE (Instituto Brasileiro de Geografia e Estatística, the Brazilian Institute for Geography and Statistics) and the highest level observed in total fruit samples in this research, represent 0.05 % and 0.20 % ADI (Acceptable Daily Intake, established by the Codex Alimentarius) for geral population and children, respectively. The assessment of EBDC intake, considering the consumption informed by IBGE (Instituto Brasileiro de Geografia e Estatística, the Brazilian Institute for Geography and Statistics) and the highest level observed in food samples (apple, tomato, papaya, lettuce, strawberry, banana, orange, carrot), monitoring from 2001 through 2004 year in the PARA (Programa de Análise de Resíduos de Agrotóxicos em Alimentos, Program Monitoring of Pesticide Residues in Food, Brazil), and that 100% of dithiocarbamate (CS2) residues from EBDC's use, represent 7.2% and 28.9% ADI for geral population and children, respectively. ETU and EBDC data in other foods (including industrialized foods), water and environment samples, together with more refined food consumption data considering more sensitive population subgroups (as children and pregnants) are necessary to evaluate the risk in a more global and realistic way in favor of Public Health.
39
Berry, Neil. "Self-assembly of transition metal dithiocarbamate receptors for ionic guest species". Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270002.
Texto completo da fonte
40
Marsh, Patrica Ann. "Metal complexes as precursors for film deposition processes". Thesis, Open University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262973.
Texto completo da fonte
41
Mathieu, Cécile. "Structure et régulation de la glycogène phosphorylase cérébrale". Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC159/document.
Texto completo da fonteResumo:
La glycogène phosphorylase (GP) est l'enzyme clé de la mobilisation du glycogène dans les cellules. Chez l'homme, cette enzyme est retrouvée sous trois isoformes dont une cérébrale (GPc). Ces trois enzymes allostériques sont régulées à la fois par fixation d'effecteurs, et par phosphorylation. Cependant, bien que très similaires, la GPc présentent des caractéristiques de régulation qui lui sont propres. Par ailleurs, la GPc possède dans sa séquence plusieurs résidus cystéines réactifs suggérant que celle-ci peut être soumise à une régulation par les espèces réactives de l'oxygène (EROs). L'objectif de ce travail a donc été d'étudier les mécanismes moléculaires et cellulaires de la régulation de la GPc. Dans un premier temps, nous avons déterminé la structure de la GPc jusqu'à présent inconnue. Ces analyses ont permis de mettre en évidence les bases structurales de la régulation de la GPc par ses effecteurs allostériques. Nous nous sommes ensuite intéressés à la régulation de cette enzyme par le H2O2. Grâce à des approches de biochimie et de biologie cellulaire, nous avons montré que le H2O2 induit la formation d'un pont disulfure intramoléculaire au niveau du site de fixation de l'AMP, empêchant l'activation de cette enzyme par son effecteur allostérique. Cette régulation, spécifique de la GPc, permet un contrôle de la glycogénolyse par phosphorylation uniquement, en condition oxydante. Enfin, nous avons mis en évidence la capacité de composés environnementaux électrophiles (pesticides) à détourner la régulation redox de la GPc, conduisant à une altération du métabolisme du glycogène et pouvant ainsi participer au développement de pathologies neurodégénérativesGlycogen phosphorylase (GP) is the key enzyme for glycogen mobilization in cells. I human, this enzyme is found as three isoforms : liver GP (lGP), muscle GP (mGP) and brain GP (bGP). These three enzymes are allosteric enzymes, regulated by both the binding of allosteric effectors and phosphorylation. However, despite GPs are highly similar, bGP display distinguishing features. In addition, highly reactive cysteine residues are found in the primary sequence of bGP, suggesting that this enzyme might be regulated by reactive oxygen species (ROS). As a consequence, we investigated the molecular and cellular regulation of the bGP. First, we determined the crystal structure of this enzyme, so far unknown. These data revealed the structural bases of bGP regulation by its allosteric effectors, leading to the activation and the inactivation of the enzyme. We then focused on the regulation of bGP by H2O2, a model of ROS. Using biochemical and cellular approaches, we showed that H2O2 induces the formation of an intramolecular disulfide bond in the AMP binding site of the enzyme, avoiding its regulation by the allosteric effectors, without affecting its regulation by phosphorylation. Under oxidative condition, this regulation, unique to the brain form of GP, allows a control of the glycogenolysis through phosphorylation only. Finally, we demonstrated that electrophilic compounds from the environment (pesticides) might divert the redox regulation of bGP, leading to the alteration of glycogen metabolism which could participate to the development of neurodegenerative diseases
42
Gowda, Vasantha. "Combined experimental and theoretical studies of dithiocarbamate complexes of yttrium, lanthanum and bismuth". Licentiate thesis, Luleå tekniska universitet, Kemiteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25701.
Texto completo da fonteResumo:
Metal-dithiocarbamate complexes find wide-ranging applications in nanomaterial and metalseparation science, and have potential use as chemotherapeutic, pesticides, and as additives tolubricants. A highly versatile dialkyldithiocarbamate (R2NCS2–) ligand can form stablecomplexes with all the transition elements and also the majority of main group, lanthanide andactinide elements. Here we present structural investigations of the molecular and electronicstructures of dialkyldithiocarbamate complexes with yttrium(III), lanthanum(III), andbismuth(III) of molecular formula [Y{S2CN(C2H5)2}3PHEN], [La{S2CN(C2H5)2}3PHEN], and[Bi2{S2CN-n(C4H9)2}6] (where PHEN=1,10-Phenanthroline) . The experimental solid-state 13Cand 15N cross polarization magic-angle-spinning (CP-MAS) NMR results are reported for allthese three complexes. We also report new single-crystal X-ray structures of heterolepticyttrium, lanthanum, and homoleptic bismuth dialkyldithiocarbamate complexes. Thecomparative analysis of powder XRD patterns and solid-state 13C and 15N CP-MAS spectra ofpolycrystalline yttrium(III) and lanthanum(III) diethyldithiocarbamato-phenanthrolinecomplexes shows the presence of significant structural differences. The diethyldithiocarbamatophenanthrolinecomplex of yttrium has a very similar structural type to a previously reported Xraydiffraction structure for [Nd{S2CN(C2H5)2}3PHEN] whereas, the crystal structure of[La{S2CN(C2H5)2}3PHEN] is considerably more complex. Our NMR and single-crystal X-raydiffraction results suggested polymorphism for bismuth di-n-butyldithiocarbamate complex.Finally, the experimental NMR results are complemented by chemical shifts obtained usingquantum chemical methods and verified the spectral assignments. Overall, our workdemonstrates how different experimental and theoretical methods can be combined that canafford insights into the solid-state structure and bonding environments of metal complexes.Godkänd; 2014; 20141024 (vasgow); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Vasantha Gowda Ämne: Gränsytors kemi/Chemistry of Interfaces Uppsats: Combined Experimental and Theoretical Studies on Dithiocarbamate Complexes of Yttrium, Lanthanum, and Bismuth Examinator: Professor Oleg Antzutkin, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: Huvudforskare John V. Hanna, Department of Physics, University of Warwick, Storbritannien Tid: Fredag den 28 november 2014 kl 10.15 Plats: C305, Luleå tekniska universitet
43
Solanki, D. "Cyanide and dithiocarbamate complexes as potential catalysts for ring-opening polymerisation of epoxides". Thesis, University College London (University of London), 2006. http://discovery.ucl.ac.uk/1445858/.
Texto completo da fonteResumo:
This thesis investigates the potential catalysis of the ring-opening polymerisation (ROP) of propylene oxide (PO). Numerous industrial and academic research groups have investigated the mechanism and developed more efficient catalysis, the leading catalysts at the moment being Double-Metal Cyanides (DMC). This thesis has considered variations to DMC catalysts as well as other potential catalysts. A combination of metal cyanides and amines were also used to form complexes, which were then characterised and tested for polymerisation. The process of ring-opening one unit of PO was examined using organic dithiocarbamates. A range of amines was used to synthesise dithiocarbamates, which were found to ring-open PO along with other epoxides. The scope was extended to include metal bis(dithiocarbamates) and consider any catalytic properties they may have towards polymerisation. Organic dithiocarbamates ranging from small groups such as methyl to rings like piperidine were attached via (bromomethyl)benzene units to form arenes with multifunctional arms. The number of bromomethyl units on the benzene varied from two to six, which allowed the arrangement of the arms to be studied and form iniferters for living polymerisation reactions. The dithiocarbamate chemistry was extended to include other transition metals, namely ruthenium and palladium. This work was developed using bidenetate phosphine ligands as well as allyl groups acting as capping end groups. Various substituted piperazine dithiocarbamates were reacted to potentially act as linking units to form multimetallic arrays.
44
Roffey, A. R. "Dithiocarbamate complexes as single source precursors to metal sulfide nanoparticles for applications in catalysis". Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1437012/.
Texto completo da fonteResumo:
Herein we report the solvothermal decomposition of a range of metal dithiocarbamate complexes for the synthesis of metal sulfide nanoparticles. Metal sulfides exist in a variety of structural phases, some of which are known to be catalytically active towards various processes. The aim of this work was to synthesise a variety of different metal sulfide phases for future catalysis testing, particularly the iron sulfide greigite (Fe3S4, a thiospinel containing Fe2+ and Fe3+) which is to be tested for CO2 reduction. A range of metal dithiocarbamate complexes were synthesised and Chapter 2 focusses on the synthesis of iron dithiocarbamates. Both iron(II) and iron(III) complexes were synthesised, the latter being a facile, open bench reaction producing a range of [Fe(S2CNRR’)3] complexes. Iron(II) bis(dithiocarbamates) are extremely air sensitive therefore carbonyl protected [Fe(S2CNRR’)2(CO)2] complexes were prepared for ease of use as precursors. The stability of the complexes was tested by TGA to ensure they were suitable precursors for metal sulfide synthesis, i.e. that the carbonyl ligands were sufficiently labile to leave the complexes before decomposition, which proved to be successful. In the following Chapter these iron dithiocarbamate complexes were solvothermally decomposed, but interestingly a combination of iron(II) and iron(III) precursors did not produce greigite as expected, but pyrrhotite (Fe7S8, containing only Fe2+). Systematic studies into the effect of decomposition temperature, precursor concentration and precursor type, on the phase and morphology of the resulting iron sulfide nanoparticles were performed on the iron(III) dithiocarbamate precursor. The phase was found to be highly dependent on both concentration and temperature. The use of a redox active additive, thiuram disulfide, on the decomposition was also investigated and found to have a significant effect, promoting the formation of the metastable greigite phase. Chapter 4 examines the nickel bis(dithiocarbamate) decomposition system to see if its behaviour was consistent with trends observed in the iron case. In general, similar trends were observed in the phase and morphology of the nickel sulfides when the decomposition parameters were varied, metastable phases were observed at lower temperature and higher concentration. The effect of thiuram disulfide on the system was greater, however, than in the iron case, whereby an additional nickel sulfide phase (NiS2) was observed at high concentration in the presence of this additive. Chapter 5 deals with a broader range of metal dithiocarbamate systems, to attempt to elucidate whether or not the trends seen for nickel and iron are universal for metal dithiocarbamate precursors. The Co, Cu, Zn and In dithiocarbamate systems were examined with and without thiuram disulfide, and some effect were seen on the phase of metal sulfide nanoparticle formed, but only at high concentration in the presence of the additive. Mixed-metal studies were performed to investigate the suitability of metal dithiocarbamates as precursors to ternary metal sulfides, and success was observed for iron-nickel, cobalt-nickel and iron-copper sulfides, though the iron-zinc and iron-indium systems only produced binary sulfides. The final Chapter looks into the metal dithiocarbamate decomposition mechanism in detail, using [Ni(S2CNiBu2)2] as a model system. NMR, in situ UV-vis, MS and powder XRD are all employed to probe the mechanism, in conjunction with XAS and computer modelling which was performed by others. The mechanism was found to rely heavily on an intermediate formed from amide exchange between the dithiocarbamate backbone and solvent amine, indicating the solvent plays an extremely significant role in the solvothermal synthesis of metal sulfides from dithiocarbamate precursors.
45
Crnogorac, Goranka. "Analysis of dithiocarbamate fungicide residues by liquid chromatography, mass spectrometry and isotope ratio mass spectrometry". Aachen Shaker, 2008. http://d-nb.info/993691447/04.
Texto completo da fonte
46
Rosa, Ana Claudia Pires da. "Avaliação dos teores de resíduos do pesticida ditiocarbamato no solo de uma cultura de couve (Brassica Oleracea L.) utilizando cloridrato de L-cisteina para preservação das amostras". Universidade do Estado do Rio de Janeiro, 2010. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=2709.
Texto completo da fonteResumo:
Os pesticidas etileno-bis-ditiocarbamatos da classe dos ditiocarbamatos estão entre os fungicidas mais empregados em todo o mundo para o controle de pragas. Muitos métodos para determinar ditiocarbamatos são baseados na hidrólise ácida em presença de cloreto estanoso e análise do CS2 gerado por diferentes técnicas. Nesse contexto, constituiram em objetivos do presente trabalho, como primeira etapa, o estudo de condições adequadas à estocagem de amostras de solo, e como segunda etapa, a avaliação das taxas de degradação e de lixiviação do fungicida mancozebe num cambissolo distrófico através do método espectrofotométrico. O sítio de estudo foi uma área delimitada de 36 m2, de uma cultura de couve, localizada em São Lourenço no 3 distrito do município de Nova Friburgo-RJ. As análises foram realizadas no laboratório de tecnologia ambiental (LABTAM/UERJ). Na primeira etapa, duas sub-amostras de solo contaminadas com mancozebe foram submetidas a tratamento com cloridrato de L-cisteina e estocadas às temperaturas ambiente e de -20C, sendo posteriormente analisadas em intervalos de 1, 7, 15 e 35 dias após a aplicação do fungicida. Outras duas sub-amostras não tratadas com cloridrato de L-cisteina foram submetidas às mesmas condições de temperatura e analisadas nos mesmos intervalos de tempo. Na segunda etapa, foi efetuada a aplicação do fungicida MANZATE 800 (Dupont Brasil, 80% mancozebe) na dose recomendada de 3,0 Kg ha-1 e coletadas amostras do solo nas profundidades de 0-10, 10-20 e 20-40 cm em intervalos de 2,5,8,12,15,18 e 35 dias após aplicação. As amostras de cada profundidade foram tratadas com cloridrato de L-cisteina e acondicionadas sob temperatura de -20C. Através dos resultados obtidos na primeira etapa, pôde-se concluir que o tratamento com cisteina foi eficaz para conservação do analito, tanto para a amostra mantida a -20C quanto para a amostra mantida à temperatura ambiente. Os dados obtidos na segunda etapa do estudo mostraram que mancozebe apresentou comportamento semelhante ao descrito na literatura, para persistência no solo. Os resultados de lixiviação mostraram que nas condições pelas quais foi conduzido o experimento, resíduos de mancozebe foram detectados em profundidades de até 40 cm, porém através dos modelos de potencial de lixiviação, concluiu-se que o fungicida não oferece risco de contaminação de águas subterrâneasEthylene-bis-dithiocarbamates pesticides of the class of dithiocarbamates fungicides are among the most widely used around the world to control pests. Many methods to determine dithiocarbamates are based on acid hydrolysis in the presence of stannous chloride and analysis of CS2 generated by different techniques. In this context, the aims of this study are to evaluate the appropriate conditions for storage of soil samples, and the rates of degradation and leaching of the fungicide mancozebe in a Cambisol by spectrophotometric method. The study site was an area of 36 m2, of a planting of cabbage, located in São Lourenço in the 3rd district of the city of Nova Friburgo-RJ. The analysis was conducted in the laboratory of environmental technology (LABTAM / UERJ). In the first step, two sub-samples of soil contaminated with mancozebe were treated with L-cysteine-HCl and stored at room temperature and -20C, then analyzed at intervals of 1,7,15 and 35 days after fungicide application. Other two sub-samples not treated with L-cysteine-HCl were subjected to the same conditions of temperature and analyzed at the same time intervals. In the second step, the fungicide MANZATE 800 (Dupont Brazil, 80% mancozeb) was applied at the recommended dose of 3.0 kg ha-1 and collected soil samples at 0-10, 10-20 and 20-40 cm at intervals of 2,5,8,12,15,18 and 35 days after application. Samples from each depth were divided into two parts, one being treated with L-cysteine-HCl and both under temperature of -20 C. The results obtained in the first step, indicate that treatment with cysteine was more effective for conservation of the analyte, both for the sample kept at -20 C and for the sample kept at room temperature. Data obtained in the second step of the study showed that mancozeb demonstrated a behavior similar to that one described in the literature to persistence in soil. The leaching results, showed that under condictions in which the experiment was conducted, mancozeb residues were detected at depths of up to 40 cm, but through the models of the potential for leaching, it was concluded that the fungicide is not liable for contamination of groundwater
47
Hoffmann, Marius Fabian [Verfasser], e Jörg [Akademischer Betreuer] Sundermeyer. "Dithiocarbamate/Trithiocarbonate: Von ionischen Flüssigkeiten über Metall-Komplexe zu Halbleitermaterialien / Marius Fabian Hoffmann ; Betreuer: Jörg Sundermeyer". Marburg : Philipps-Universität Marburg, 2020. http://d-nb.info/1224046846/34.
Texto completo da fonte
48
Klein, Mark Stephen. "The Determination of Lead and Cadmium in Tobacco Using High Performance Liquid Chromatography and Dithiocarbamate Derivitization". Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etd/1240.
Texto completo da fonteResumo:
A reversed phase-high performance liquid chromatography method has been developed that is capable of resolving lead and cadmium diethyldithiocarbamate complexes. The method does not require the presence of hazardous solvents to optimize peak shape and resolution; the mobile phase consists of methanol, water, and a surfactant. Tobacco samples were chemically oxidized and reacted with sodium diethyldithiocarbamate reagent prior to analysis using the HPLC method. The lead diethyldithiocarbamate determination was compromised by the presence of a significant interference in the analysis; lead determinations in 10 foreign and domestic tobacco samples ranged from 27.14 to 134.84 μg/g. The cadmium diethyldithiocarbamate determination was not adversely affected by interferences. Cadmium determinations in 10 foreign and domestic tobacco samples ranged from 0.89 to 6.96 μg/g. The tobacco samples were also analyzed using atomic absorption spectrometry. Foreign tobacco brands that contained clove as a spice showed lower levels of cadmium and lead.
49
Crnogorac, Goranka [Verfasser]. "Analysis of Dithiocarbamate Fungicide Residues by Liquid Chromatography/Mass Spectrometry and Isotope Ratio Mass Spectrometry / Goranka Crnogorac". Aachen : Shaker, 2009. http://d-nb.info/1156517389/34.
Texto completo da fonte
50
Sacht, Cheryl. "Oligoether and oligothioether podands with quinolyloxy and dithiocarbamato terminal groups : synthesis, characterization and coordination chemistry". Thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/23376.
Texto completo da fonte