970 resultados para Cobalt(II) complexes


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Mealybugs (Hemiptera: Pseudococcidae) are major pests of a wide range of crops and ornamental plants worldwide. Their high degree of morphological similarity makes them difficult to identify and limits their study and management. We aimed to identify a set of markers for the genetic characterization and identification of complexes of taxa in the Pseudococcidae. We surveyed and tested the genetic markers used in previous studies and then identified new markers for particularly relevant genomic regions for which no satisfactory markers were available. We tested all markers on a subset of four taxa distributed worldwide. Five markers were retained after this first screening: two regions of the mitochondrial cytochrome oxidase I gene, 28S-D2, the entire internal transcriber space 2 locus and the rpS15-16S region of the primary mealybug endosymbiont Tremblaya princeps. We then assessed the utility of these markers for the characterization and identification of 239 samples from 43 sites in France and Brazil. The five markers studied (i) successfully distinguished all species identified by morphological examination, (ii) disentangled complexes of species by revealing intraspecific genetic variation and identified a set of closely related taxa for which taxonomic status requires clarification through further studies, and (iii) facilitated the inference of phylogenetic relationships between the characterized taxa.

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This final thesis is aimed at summarizing the research program I have carried out during my PhD studies, that has been dealing with the design, the preparation, characterization and applications of new Re(I), Ru(II), and Ir(III) metal complexes containing anionic ligands such as 5-aryl tetrazolates [R-CN4]- or their neutral analogues, N-alkyltetrazoles [R-CN4-R1]. Chapter 1 consists of a brief introduction on tetrazoles and metal-tetrazolato complexes, and on the photophysical properties of d6 transition metal complexes. In chapter 2, the synthesis, characterization and study of the photophysical properties of new luminescent Ir(III)-tetrazolate complexes are discussed. Moreover, the application of one of the new Ir(III)-CN complexes as emissive core in the fabrication of an OLED device is reported. In chapter 3, the study of the antimicrobial activity of new Ru(II)-alkyltetrazole complexes is reported. When the pentatomic ring was substituted with a long alkyl residue, antimicrobial activity toward Deinococcus radiodurans was observed. In chapter 4, a new family of luminescent Re(I)-tetrazolate complexes is reported. In this study, different N-alkyl tetrazoles play the role of diimine (diim) ligands in the preparation of new Re(I) tricarbonyl complexes. In addition, absorption and emission titration experiments were performed to study their interaction with Bovine Serum Albumin (BSA). In chapter 5, the synthesis and characterization of new luminescent Re(I)-tetrazolate complexes are discussed. The use of sulfonated diimine ligands in the preparation of new Re(I) tricarbonyl complexes led to the first example Re(I) complexes for the luminescent staining of proteins. In chapter 6, the synthesis, a new family of Ir(III)-NO2 tetrazole complexes displaying unexpected photophysical properties are discussed. Moreover, the possibility to tune the luminescent output of such systems upon chemical modification of the pending nitro group was verified by performing reduction tests with sodium dithionite; this represents encouraging evidence for their possible application as hypoxia-responsive luminescent probes in bioimaging.

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Solid state engineered materials have proven to be useful and suitable tools in the quest of new materials. In this thesis different crystalline compounds were synthesized to provide more sustainable products for different applications, as in cosmetics or in agrochemistry, to propose pollutants removal strategy or to obtain materials for electrocatalysis. Therefore, the research projects presented here can be divided into three main topics: (i) sustainable preparation of solid materials of widely used active ingredients aimed at the reduction of their occurrence in the natural environment. The systems studied in this section are cyclodextrins host-guest compounds, obtained via mechanochemical and slurry synthesis. The first chemicals studied are sunscreens inclusion complexes, that proved to have enhanced photostability and desired photoprotection. The same synthetic methods were applied to obtain inclusion complexes of bentazon, a herbicide often found to leach in groundwaters. The resulting products showed to have desired water solubility properties. The same herbicide was also adsorbed on amorphous calcium phosphate nanoparticles, to obtain a biocompatible formulation of this agrochemical. This herbicide could benefit by the adsorption on nanoparticles for what concerns its kinetic release in different media as well as its photostability. (ii) Sustainable synthesis of co-crystals based on polycyclic aromatic hydrocarbons, for the proposal of a sequestering method with a resulting material with enhanced properties. The co-crystallization via mechanochemical means proved that these pollutants can be sequestered via simple solvent-free synthesis and the obtained materials present better photochemical properties when compared to the starting co-formers. (iii) Crystallization from mild solvents of nanosized materials useful for the application in electrocatalysis. The study of compounds based on nickel and cobalt metal ions resulted in the obtainment of 2D and 1D coordination polymers. Moreover, solid solutions were obtained. These crystals showed layered structures and, according to preliminary results, they can be exfoliated.

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The program of my PhD studies has been dealing with the investigation of the research outcomes that may result from the use of luminescent Iridium(III) cyclometalated complexes in the field of polymer science. In particular, my activity has been focused on exploring two main applicative contexts, i.e. Ir(III) complexes for preparing polymers and in combination with polymers. In the first part, a new set of luminescent Ir(III) complexes was exploited as photocatalysts for light-assisted atom transfer radical polymerization of methyl methacrylate. The decoration of both cyclometalated and ancillary ligands with sp3 hybridized nitrogen substituents together with the use of specific counterions, imparted suitable photophysical and redox properties for an efficient photocatalyzed process. The second part has been focused on the employment of Ir(III) tetrazole complexes as phosphorescent dyes in polymeric materials. Colourless luminescent solar concentrators were prepared blending two Ir(III) cyclometalates with acrylate polymers. Their performances were investigated, leading to promising outcomes comparable, or superior, to those obtained from colourless LSCs based on organic fluorophores. As a complementary approach, Ir(III) complexes were covalently linked to polymers in the side chain, to obtain a new class of metallopolymers. To this extent, a bifunctional tetrazolate molecule, equipped with a coordination site and a polymerizable unit, was designed. The photophysical properties of the resultant luminescent polymeric films were discussed. In the end, an additional project involving both polymers and metal compounds was carried out during my experience as a visiting PhD student at Humboldt – University of Berlin. Polystyrene and polyethylene glycol -based ion-exchange resins were functionalized with peptides through a ligation pathway, for the selective chelation of Copper(II) in aqueous solutions. The coordinating capability of the materials towards Cu2+ ions was tested by ICP-MS analysis. The resins strategically modified with ion-selective peptides, may be exploited in the preparation of water-processing devices.

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In this study, 103 unrelated South-American patients with mucopolysaccharidosis type II (MPS II) were investigated aiming at the identification of iduronate-2-sulfatase (IDS) disease causing mutations and the possibility of some insights on the genotype-phenotype correlation The strategy used for genotyping involved the identification of the previously reported inversion/disruption of the IDS gene by PCR and screening for other mutations by PCR/SSCP. The exons with altered mobility on SSCP were sequenced, as well as all the exons of patients with no SSCP alteration. By using this strategy, we were able to find the pathogenic mutation in all patients. Alterations such as inversion/disruption and partial/total deletions of the IDS gene were found in 20/103 (19%) patients. Small insertions/deletions/indels (<22 bp) and point mutations were identified in 83/103 (88%) patients, including 30 novel mutations; except for a higher frequency of small duplications in relation to small deletions, the frequencies of major and minor alterations found in our sample are in accordance with those described in the literature.

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We report on the shape resonance spectra of phenol-water clusters, as obtained from elastic electron scattering calculations. Our results, along with virtual orbital analysis, indicate that the well-known indirect mechanism for hydrogen elimination in the gas phase is significantly impacted on by microsolvation, due to the competition between vibronic couplings on the solute and solvent molecules. This fact suggests how relevant the solvation effects could be for the electron-driven damage of biomolecules and the biomass delignification [E. M. de Oliveira et al., Phys. Rev. A 86, 020701(R) (2012)]. We also discuss microsolvation signatures in the differential cross sections that could help to identify the solvated complexes and access the composition of gaseous admixtures of these species.

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Sickle cell disease (SCD) pathogenesis leads to recurrent vaso-occlusive and hemolytic processes, causing numerous clinical complications including renal damage. As vasoconstrictive mechanisms may be enhanced in SCD, due to endothelial dysfunction and vasoactive protein production, we aimed to determine whether the expression of proteins of the renin-angiotensin system (RAS) may be altered in an animal model of SCD. Plasma angiotensin II (Ang II) was measured in C57BL/6 (WT) mice and mice with SCD by ELISA, while quantitative PCR was used to compare the expressions of the genes encoding the angiotensin-II-receptors 1 and 2 (AT1R and AT2R) and the angiotensin-converting enzymes (ACE1 and ACE2) in the kidneys, hearts, livers and brains of mice. The effects of hydroxyurea (HU; 50-75mg/kg/day, 4weeks) treatment on these parameters were also determined. Plasma Ang II was significantly diminished in SCD mice, compared with WT mice, in association with decreased AT1R and ACE1 expressions in SCD mice kidneys. Treatment of SCD mice with HU reduced leukocyte and platelet counts and increased plasma Ang II to levels similar to those of WT mice. HU also increased AT1R and ACE2 gene expression in the kidney and heart. Results indicate an imbalanced RAS in an SCD mouse model; HU therapy may be able to restore some RAS parameters in these mice. Further investigations regarding Ang II production and the RAS in human SCD may be warranted, as such changes may reflect or contribute to renal damage and alterations in blood pressure.

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A monomeric basic PLA2 (PhTX-II) of 14149.08 Da molecular weight was purified to homogeneity from Porthidium hyoprora venom. Amino acid sequence by in tandem mass spectrometry revealed that PhTX-II belongs to Asp49 PLA2 enzyme class and displays conserved domains as the catalytic network, Ca2+-binding loop and the hydrophobic channel of access to the catalytic site, reflected in the high catalytic activity displayed by the enzyme. Moreover, PhTX-II PLA2 showed an allosteric behavior and its enzymatic activity was dependent on Ca2+. Examination of PhTX-II PLA2 by CD spectroscopy indicated a high content of alpha-helical structures, similar to the known structure of secreted phospholipase IIA group suggesting a similar folding. PhTX-II PLA2 causes neuromuscular blockade in avian neuromuscular preparations with a significant direct action on skeletal muscle function, as well as, induced local edema and myotoxicity, in mice. The treatment of PhTX-II by BPB resulted in complete loss of their catalytic activity that was accompanied by loss of their edematogenic effect. On the other hand, enzymatic activity of PhTX-II contributes to this neuromuscular blockade and local myotoxicity is dependent not only on enzymatic activity. These results show that PhTX-II is a myotoxic Asp49 PLA2 that contributes with toxic actions caused by P. hyoprora venom.

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Type II diabetes mellitus is a highly prevalent disease among the adult Brazilian population, and one that can be controlled by interventions such as physical activity, among others. The aim of this randomized controlled study was to evaluate the impact of a traditional motivational strategy, associated with the activation of intention theory, on adherence to physical activity in patients with type II, diabetes mellitus who are part of the Unified Health System (SUS). Participants were divided into a control group (CG) and an intervention group (IG). In both groups, the traditional motivational strategy was applied, but the activation of intention strategy was only applied to the IG Group. After a two-month follow-up, statistically significant differences were verified between the groups, related to the practice of walking (p = 0.0050), number of days per week (p = 0.0076), minutes per day (p = 0.0050) and minutes walking per week (p = 0.0015). At the end of the intervention, statistically significant differences in abdominal circumference (p = 0.0048) between the groups were observed. The conclusion drawn is that the activation of intention strategy had greater impact on adherence to physical activity and reduction in abdominal circumference in type II diabetics, than traditional motivational strategy.

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This paper discusses the results obtained with homogeneous catalytic ozonation [Mn (II) and Cu (II)] in phenol degradation. The reduction of total phenols and total organic carbon (TOC) and the ozone consumption were evaluated. The efficiency in phenol degradation (total phenol removal) at pH 3, with the catalytic process (Mn (II)), increased from 37% to 55% while the TOC removal increased from 4 to 63% in a seven-minute treatment. The ozonation process efficiency at pH 10 was 43% and 39% for phenol and TOC removal, respectively. The presence of both metallic ions (Mn2+ and Cu+2) in the ozonation process resulted in a positive effect.