Zugl.: Aachen, Techn. Hochsch., Diss., 2008

Techn. Hochsch., Diss., 2004--Aachen.

A citricultura brasileira ocupa lugar de destaque no agronegócio nacional, sendo o país o maior produtor de laranja e suco de laranja do mundo. A faia (Fagus sylvatica) é uma das principais espécies das florestas na Europa, sendo usada como ornamental e por possui alto valor econômico devido à produção de madeira. Um dos principais entraves no cultivo dessas espécies é a ocorrência de doenças principalmente as causadas por espécies de Phytophthora que além de causar grandes prejuízos, os métodos de controle são difíceis e onerosos. Existem trabalhos na literatura que apontam os fosfitos como alternativa sustentável, eficaz e economicamente viável para o controle de doenças causadas por oomicetos. Entretanto, o Comitê de Ação a Resistência à Fungicidas (FRAC) classifica os fosfitos, como produtos com ingrediente ativo sem mecanismo de ação definido. Neste contexto, este trabalho teve como objetivo avaliar o produto comercial à base de fosfito de potássio, Phytogard® no controle das doenças causadas por Phytophthora nicotianae em citros e Phytophthora plurivora em faia, bem como avaliar através de análises bioquímicas se esse produto induz resistência em plântulas de citros. Além disso, foram realizados estudos in vitro para avaliar o efeito direto do Phytogard® sobre o desenvolvimento de P. nicotianae e P. plurivora e verificar os possíveis mecanismos de ação desse produto sobre esses patógenos. Foram utilizadas plântulas de citros e faia que foram aspergidas com diferentes concentrações de Phytogard® e, posteriormente, inoculadas com os patógenos. Foram avaliadas a incidência das doenças, o consumo de água e a quantidade de DNA dos patógenos nos tecidos das raízes dos hospedeiros. Ao final do experimento, foram realizadas análises bioquímicas dos tecidos das plântulas de citros. Nos experimentos in vitro, o micélio dos patógenos foi exposto a concentrações crescentes de Phytogard® sendo determinado o crescimento micelial, produção de massa fresca de micélio e de zoósporos. Avaliou-se a perda de eletrólitos, peroxidação de lipídios e a atividade da enzima β-1,3 glucanase do micélio exposto ao produto. Foi avaliada também a morfologia das hifas tratadas ou não com o Phytogard® através da técnica de Microscopia Eletrônica de Varredura (MEV). Os resultados mostraram que o Phytogard®, em todas as concentrações aplicadas controla de maneira preventiva as doenças causadas por P. nicotianae e P. plurivora em citros e faia, respectivamente. Em citros, o produto altera a atividade de algumas proteínas relacionadas à patogênese, mas não é possível concluir que o controle seja mediado por indução de resistência. O Phytogard® inibe o crescimento micelial e a produção de zoósporos de P. nicotianae e P. plurivora. Além disso, o produto modifica a morfologia das hifas, atua na permeabilidade de membrana e na síntese de parede celular do micélio dos patógenos. / The Brazilian citrus production is important to national agribusiness, and the country is the largest orange and orange juice world producer. Beech (Fagus sylvatica) is one of the main forest species in Europe and is used as ornamental and also it has a high economic value due to the production of wood. One of the main problems in the cultivation of these species is the occurrence of diseases, mainly caused by Phytophthora species. Besides causing extensive damage control methods are difficult and costly. There are studies in the literature that show phosphites as a sustainable alternative, effective and economically viable for the control of diseases caused by oomycetes. However, the Fungicide Resistance Action Committee (FRAC), classifies the phosphites as products with the active ingredient with no defined mode of action. In this context, this work aimed to evaluate the commercial product based on potassium phosphite Phytogard® on the control of diseases caused by Phytophthora nicotianae in citrus plants and Phytophthora plurivora in beech plants and evaluate through biochemical assays whether this product induces resistance in citrus seedlings. In addition, in vitro studies were carried out to evaluate the direct effect of Phytogard® on the development of P. nicotianae and P. plurivora and to understand the possible mode of action of the product on these pathogens. Citrus seedlings were sprayed with different concentrations of Phytogard® and then inoculated with the pathogen. We evaluated the diseases incidence, water uptake and the amount of pathogens DNA in the host roots. At the end of the experiment, biochemical assays with citrus seedlings were made. In in vitro experiments, the pathogen mycelium was exposed to increasing concentrations of Phytogard® and mycelial growth, production of fresh mycelium and zoospores by these pathogens were determined. We also evaluated the electrolyte leakage, lipid peroxidation and the β-1,3 glucanase activity in the mycelium exposed to the product. It was also evaluated the hyphae morphology from mycelium treated or not with Phytogard® by using scanning electron microscopy. The results showed that in all concentrations of Phytogard® preventively controled diseases caused by P. nicotianae and P. plurivora in citrus and beech plants, respectively. In citrus, the product changed the activities of some pathogenesis-related proteins, but it is not possible to conclude that the control was mediated by resistance induction. The Phytogard® inhibited mycelial growth and zoospore production by P. nicotianae and P. plurivora. Furthermore, the product modified the hyphae morphology, changed membrane permeability and mycelium cell wall synthesis in the pathogens.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The effectiveness of defense activation in different soybean cultivars against Phakopsora pachyrhizi promoted by phosphite, as well as its association with fungicides in different timing application in relation to pathogen inoculation, was studied in greenhouse conditions in two trials carried out in completely randomized design, with four replications. The results showed that phosphite was unable to induce defense, because it was not observed any reduction on severity, pustules.cm-2 number, and Area Under Progress Disease Curve (AUPDC) by application of the product. The progress disease was slower in the cultivar Fundacep 55, which had a AUPDC 53% lower than cultivar Fundacep 56, the more susceptible cultivar. The fungicide epoxiconazole + pyraclostrobin reduced in almost 29% the AUPDC value when compared to isolated triazol use, considering the timing application average. The applications nearer to inoculation and the preventive fungicide applications were more effective than those applications done earlier or later in relation to plant infection by the pathogen. The data found suggest that phosphite does not induce resistance in soybean against P. pachyrhizi, but they demonstrate that there is variation on partial resistance of cultivars and on the effectiveness of fungicides between themselves and in relation to timing application of them. The Asian rust has been a great concern, due to its big potential damage and to the limited availability of control measures. This work evaluated the effect of potassium phosphite (PP) isolated and combined with epoxiconazole + pyraclostrobin, in two soybean cultivars and different fertilization levels, under Asian rust control, defoliate, yield components and grain yield. One or two PP applications were done, combined or not to fungicide (R1 and R1 + R3). Higher area under progress disease curve (AUPDC) and defoliate values were observed in the cultivar Coodetec 219 in relation to MSoy 8000. PP promoted average reduction of 9% in AUPDC and did not influence the defoliate. The AUPDC of control plot of cultivar MSoy 8000 without fertilization was 2.4-fold increased compared to 65 kg.ha-1 de P2O5 + 105 kg.ha-1 de K2O supply. The pods number, thousand grain weight and grain yield were not affected by PP. The cultivars presented difference on grain yield according to fertilizer level. The cultivar MSoy was more responsive to P nutrition, whereas on the cultivar Coodetec 219 the higher effect was due to K fertilization. / A ferrugem asiática da soja tem elevado potencial de dano e uma limitada disponibilidade de medidas de controle. A efetividade da ativação de mecanismos de defesa em diferentes cultivares de soja contra Phakopsora pachyrhizi proporcionada pelo fosfito, bem como sua associação com fungicidas aplicados em diferentes épocas em relação à inoculação com o patógeno, foi estudada em condições de casa-de-vegetação (CV) em dois ensaios conduzidos no delineamento inteiramente casualizado, com quatro repetições. A campo foi avaliado o efeito do fosfito de potássio (FP) isolado e associado ao fungicida epoxiconazol + piraclostrobina, em duas cultivares de soja e sob diferentes níveis de adubação de base, sobre o controle da ferrugem asiática, desfolha, componentes de rendimento e rendimento de grãos. Os resultados obtidos em CV mostraram que o fosfito não foi capaz de induzir a expressão dos mecanismos de defesa, uma vez que não foi observada qualquer redução na severidade, número de pústulas.cm-2, e na Área Abaixo da Curva de Progresso de Doença (AACPD) por conta da aplicação do produto. O progresso da ferrugem asiática foi mais lento na cultivar Fundacep 55, que teve uma AACPD 53% menor do que a cultivar Fundacep 56, a mais suscetível. O fungicida epoxiconazol + piraclostrobina proporcionou uma redução na AACPD de quase 29% quando comparado ao emprego do triazol isolado na média das épocas de aplicação, sendo que as aplicações mais próximas da inoculação e preventivas foram mais efetivas do que aquelas realizadas de forma muito precoce ou muito tardia em relação à infecção das plantas pelo patógeno. Os resultados encontrados sugerem que o fosfito de potássio não induz resistência em soja contra P. pachyrhizi, porém demonstram que há variação na resistência parcial à ferrugem asiática por parte das cultivares e na efetividade dos fungicidas entre si e quanto ao momento em que os mesmos são aplicados. Os resultados a campo mostraram maiores valores de AACPD e desfolha na cultivar Coodetec 219 em relação à MSoy 8000. O FP promoveu redução média de 9% na AACPD e não influenciou a desfolha. A AACPD do tratamento testemunha da cultivar MSoy 8000 sem adubação foi 2,4 vezes superior àquele com 65 kg.ha-1 de P2O5 + 105 kg.ha-1 de K2O. O número de legumes por planta, massa de mil grãos e rendimento não foram afetados pelo FP. As cultivares apresentaram diferença no rendimento de grãos conforme a nutrição utilizada, com maior efeito devido ao P na cultivar MSoy 8000 e devido ao K na Coodetec 219.

The ability of gold(I) to activate many types of unsaturated bonds toward nucleophilic attack was not widely recognized until the early 2000s. One major challenge in gold catalysis is the control over regioselectivity when there are two or more possible products as a result of complicated mechanistic pathways. It is well know that the choice of ligand can have dramatic effects on which pathway is being followed but very rarely are the reasons for this selectivity understood. The synthesis of new acyclic diaminocarbenes was developed and a study of the ligand effects on the regioselectivity of a gold-catalyzed domino enyne cyclization hydroarylation reaction and a Nazarov cyclization was undertaken. New chiral acyclic diaminocarbenes were also developed and tested along side new C3-symmetric phosphite ligands in an asymmetric intramolecular hydroamination of allenes. Structure activity correlations were developed for the potential use in further rational ligand design. The synthesis of 6a,7-dihydro-5-amino-dibenzo[c,g]chromene derivatives via a gold-catalyzed domino reaction of alkynylbenzaldehydes in the presence of secondary amines was developed. These were sent to be screened for biological activity.

<p> This thesis is primarily concerned with an investigation of the reaction of tetrakis(tri-p-tolyl phosphite)nickel(0) with strong acids, using 1H, 31P and 2H NMR. The results differ from those previously obtained for similar reactions with other Ni(0) phosphites, in that both five and four-coordinate nickel hydrides are formed in concentrations sufficient for spectroscopic studies. The four-coordinated hydride is believed to be the catalytically active species in a number of reactions catalyzed by Ni(0) phosphites. Variable-temperature studies show that the four-coordinate hydride complex is a fluxional molecule. The exchange process is exclusively intramolecular in nature.</p> <p> A very simple method was used to analyze the NMR data and obtain activation parameters for the exchange process. These parameters were compared with those reported in the literature for related intramolecular and intermolecular reactions. The large negative entropy of activation is interpreted in terms of ion pairing in the transition state. NMR evidence for the structure of the products resulting from the reactions of acids with both the metal complexes and the free phosphite ligands is presented. The conditions necessary for the observation of four-coordinated nickel hydrides are also discussed.</p> / Thesis / Master of Science (MSc)

La maîtrise de l’additivation est l’un des enjeux majeurs de la formulation des lubrifiants, notamment pour l’industrie automobile. La formulation d’une huile est toutefois très complexe en raison du nombre important d’additifs et des nombreuses interactions possibles entre additifs, notamment entre les additifs de surface. Les phosphites organiques et les polysulfures organiques ont déjà montré leur efficacité en tant qu’additifs de surface. Toutefois malgré leur usage répandu dans les formulations des lubrifiants automobiles, peu d’études traitent des interactions pouvant avoir lieu entre ces deux types de composés. Ce travail de thèse a pour objectif la compréhension des mécanismes d’interaction (antagonisme/synergie) pouvant exister entre les phosphites organiques et les polysulfures organiques. Pour cela, une approche originale sur la lubrification par la phase gazeuse s’est avérée très pertinente. Le couplage du Tribomètre à Environnement Contrôlé (TEC) avec les systèmes d’analyses de surface XPS/Auger a permis d’analyser les tribofilms générés in situ et d’éviter ainsi toute contamination et/ou oxydation du tribofilm avant analyse. Les molécules choisies sont les additifs de lubrification industriels (polysulfures tertaires) à faibles poids moléculaires ou alors des molécules à faible poids moléculaires ayant les mêmes fonctions chimiques que les additifs usuels : trimethyl phosphite (TMPi), dimethyl phosphite (DMPi). L’étude des réactions des tribochimiques des molécules phosphorés a permis de mettre en évidence le rôle ambivalent du DMPi qui se comporte à la fois comme un phosphite pour former un phosphure de fer et comme un phosphate. Le mécanisme formation du phosphure de fer a peu être étayé par la réalisation de calculs ab initio sur l’adsorption dissociative du TMPi sur une surface de fer. Les TPS étudiés génèrent quant à eux des tribofilms à base disulfure de fer. Les mélanges binaires réalisés en phase gazeuse ont permis de mettre en évidence l’importance des rapports de concentrations des vapeurs introduites et du mode d’introduction des molécules dans le tribomètre. Les résultats obtenus en tribologie en phase gazeuse ont été corroborés par des essais complémentaires en phase liquide. / Mastering the addivation is one of the biggest issues for the lubricants formulation, especially in the automobile industry. However automotive lubricants are very complex systems due to the numerous additives mixed with base oils. Many interactions can occur between additives, especially between surface additives. Organic phosphites and organic polysulphides have already demonstrated their effectiveness as surface additives. However, despite their widespread use in the formulations of automotive lubricants, few studies deal with the interactions taking place between these two types of compounds. The aim of this study is to understand the interactions, antagonistic or synergetic effect between these kinds of additives using Gas Phase Lubrication (GPL) approach. A Environmental Controlled Tribometer (TEC) was used as a tool to simulate the interaction between organophosphate additives and polysulfurous additives. In situ surface analysis was performed in the tribofilm formed during friction using of X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy(AES) in order to avoid any oxidation or air contamination. The molecules selected for the study can be same as the additive like the TPS molecules which are widely used as lubricant additives. Howeverto simulate the phosphite chemical function of phosphite additives, we need to select smaller molecule having the same chemical function. These molecules are dimethyl phosphite (DMPi), trimethylphosphate (TMPi) for simulating the phosphite chemical function and organic polysulphides (TPS44and TPS32). The study of the tribochemical reactions of organic phopshites allowed to clearly characterise the ambivalence of DMPi, which can react like a phosphite and induce iron phosphide formation or react like a phosphate. Ab initio numerical simulation on TMPi dissociative adsorption was carried out to identify the reactions pathways leading to iron phosphide formation. The tribochemical reaction of TPS44 on metallic iron surface leads to the formation of iron disulphidebased tribofilm. The binary vapours mixtures studied by GPL allowed to clearly identify the importance of the vapour concentration ratio between phosphite and polysulphide. Liquid phase experiments were also carried out to confirm the trend observed in GPL approach.

: Les plantes ont développé au cours de leur évolution un système d’immunité innée constitué de barrières préformées et de réponses de défense induites contre les agents pathogènes. Ce travail s’inscrit dans l’étude des résistances induites chez Arabidopsis thaliana soit naturellement contre les agents pathogènes racinaires Fusarium oxysporum spp. (Fo), ou après application de phosphite (Phi), contre le parasite foliaire Hyaloperonospora arabidopsidis (Hpa). Dans la première partie du travail, les rôles des métabolites secondaires (MS) et des formes réactives de l’oxygène (ROS) dans les résistances racinaires basale et non-hôte, respectivement aux formes spéciales conglutinans (Foco) et melonis (Fom) de Fo, ont été analysés. Nous avons démontré la participation de la camalexine, une phytoalexine indolique, dans la résistance basale d’Arabidopsis à Foco. En revanche, la scopolétine, une phytoalexine phénolique, et les ROS jouent des rôles essentiels dans la résistance non-hôte à Fom. Ces données soulignent le rôle clé des MS et des ROS dans les résistances hôte et non-hôte d’Arabidopsis. Dans une deuxième partie de ce travail, le mode d’action du Phi, un oxyanion de l’acide phosphoreux (H3PO3) protégeant Arabidopsis contre l’isolat Noco2 de Hpa, a été étudié. L’effet de faibles doses de Phi est aboli chez des mutants d’Arabidopsis affectés dans la voie de transduction du signal acide salicylique (SA) indiquant que l’induction de résistance à Hpa est médiée par des mécanismes dépendants du SA. Le Phi potentialise les réponses de défense contre Hpa Noco2 via EDS1-PAD4, deux composants essentiels de la résistance basale, NPR1 et la protéine de défense PR1. L’expression de la MAP kinase MPK4, un régulateur négatif de la résistance à Hpa, est diminuée par le Phi, lors de l’inoculation par Hpa Noco2. Nos résultats démontrent que la potentialisation des réponses de défense par le Phi est associée à la régulation négative de MPK4. / Plants have developed during their evolution an innate immunity system consisting of preformed barriers and induced defence responses against pathogens. This work studies resistances in Arabidopsis thaliana induced either naturally against the root pathogen Fusarium oxysporum spp. (Fo), or after application of phosphite (Phi) against the leaf pathogen Hyaloperonospora arabidopsidis (Hpa). In a first part, roles of secondary metabolites (SM) and reactive oxygen species (ROS) in basal and non-host resistances of roots to the special forms conglutinans (Foco) and melonis (Fom) of Fo, respectively, were analyzed. We demonstrated the involvement of the indolic phytoalexin camalexin, in basal resistance of Arabidopsis to Foco. In contrast, the phenolic phytoalexin, scopoletin, and ROS play essential roles in non-host resistance to Fom. These data underscore the key role of MS and ROS in basal and non-host resistances of Arabidopsis. In a second part, the mode of action of Phi, an oxyanion of phosphorous acid (H3PO3) protecting Arabidopsis against the Hpa isolate Noco2 was studied. Effect of low doses of Phi is abolished in Arabidopsis mutants affected in salicylic acid (SA) signalling, indicating that induced resistance to Hpa is mediated by SA-dependent mechanisms. Phi primes defence responses against Hpa Noco2 via EDS1-PAD4, two essential components of basal resistance, as well as NPR1 and PR1. Expression of the MAP kinase MPK4, a negative regulator of resistance to Hpa, is decreased by Phi after inoculation with Hpa Noco2. Our results demonstrate that priming of defence responses by Phi is associated with down-regulation of MPK4.

Cette thèse présente la synthèse de ligands originaux construits sur des plateformes coniques de type résorcin[4]arène ou calix[4]arène étant susceptibles de positionner un métal à proximité d'une unité réceptrice: a) des bis-binaphtylphosphites optiquement actifs dont les centres phosphorés ont été greffés sur le bord supérieur de cavités génériques. Ces coordinats ont été testés en hydroformylation asymétrique d’arènes vinyliques et ont conduit à une sélectivité iso très élevée avec de bons, voire très bons excès énantiomériques; b) des carbènes N- hétérocycliques ayant soit un, soit les deux atomes d'azote substitués par des unités résorcinarényle (variante cavitand) et leur utilisation pour la formation d'espèces comportant un centre métallique supramoléculairement piégé dans la partie cavitaire (complexes du type [NiXCpL] (X = Br ou Cl, Cp = cyclopentadiényle, LH = NHC). Ces complexes se sont avérés efficaces en dimérisation de l'éthylène; c) des carbènes N-hétérocyliques anormaux obtenus à partir de sels de triazolium comportant un ou deux substituants résorcinarène. Ces composés à fort encombrement ont été efficacement employés en couplage croisé de Suzuki-Miyaura entre des chlorures d'aryles volumineux et des acides arylboroniques stériquement encombrés. Les activités les plus importantes ont été obtenues avec le sel de triazolium stériquement le moins encombré, celui portant un seul substituant résorcinarène. Sa plus grande efficacité est due à une approche plus facile des substrats dans les intermédiaires catalytiques correspondants ainsi que de la présence de groupes pentyles flexibles pouvant interagir stériquement avec le centre métallique de manière à faciliter l'étape d'élimination réductrice / This thesis describes the synthesis of a series of compounds built on conical resorcin[4]arene and calix[4]arene platforms: a) diphosphites derived from optically active binol, in which the phosphite moieties have been grafted to the wider rim of the generic cones. These ligands were assessed in asymmetric hydroformylation of vinyl arenes and led to high iso selectivity with good to excellent enantiomeric excess; b) N-heterocyclic carbenes bearing either one or two cavitand moieties and their use for the synthesis of [NiXCpL] complexes (X = Br or Cl, Cp = cyclopentadienyl, LH = NHC) in which the NiCp moiety has been supramolecularly trapped in a resorcinarene bowl. These complexes were found active in ethylene dimerization; c) bulky triazolium salts with one or two resorcinarene substituents that were found suitable for the synthesis of complexes with abnormal NHCs. The latter were tested in palladium-catalysed Suzuki-Miyaura cross-coupling of bulky aryl chlorides with sterically hindered aryl boronic acids. Better activities were observed with the sterically less hindered triazolium salt, which bears a single resorcinarene substituent. Its higher efficiency arises from a higher substrate accessibility in the resulting catalytic intermediates as well as the presence of flexible pentyl groups that may interact with the metal centre so as to facilitate the reductive elimination step.

Calixarenes, particularly calix[4]arenes, continue to attract considerable attention in synthetic chemistry, notably as platforms for designing sophisticated molecular cages and claw-like ligands. Incorporation of phosphorus containing fragments into the calix[4]arene framework gives rise to new class of phosphorus ligands, called “calixphosphines”, a class of molecules that combine a catalytic center (a transition metal) and a molecular receptor. This area of research has been growing rapidly in recent years. This thesis deals with the synthesis and a systematic study of conformational aspects of phosphorus functionalized calix[4]arene ligands and their palladium complexes. Several phosphorus functionalized calix[4]arene ligands and their (allyl) palladium complexes have been synthesized. The new compounds have been characterized by elemental analysis, NMR and IR spectroscopic data. The molecular structures of some representative compounds have been confirmed by single crystal X-ray diffraction studies. Chapter 1 provides a brief overview of phosphorus functionalized calix[4]arenes and their transition metal chemistry with emphasis on aspects related to the theme of the present study. The scope and aim of the present investigation is outlined at the end of this chapter. Chapter 2 presents the results obtained in the present investigation and a discussion of these results, especially spectroscopic and X-ray crystallographic data. The highlights of the present investigation and possible future directions are summarized at the end of this chapter. Chapter 3 contains relevant details of the experimental procedures for the synthesis of calix[4]arene phosphite ligands and their palladium complexes. Spectroscopic and analytical data of these compounds are also given in this chapter. The details of single crystal diffraction studies are included at the end of this chapter. The references to the literature are compiled at the end of the thesis and are indicated in the text by appropriate numbers appearing as superscripts. The compounds synthesized in the present study are represented by bold arabic numerals. The abbreviations employed in this thesis are those generally used in Chemical Abstracts.