Síntese e caracterização de complexo tetranuclear de cobre com o ligante resorcinareno

The main objective of the present work is to contribute to the development of the coordination chemistry of macromolecules such as resorcinarene with the synthesis and characterization of new copper complexes with chloride, vanillin and resorcinarene binders, all coordinated to phenanthroline, a biologically active molecule with important properties in biological systems. The complex [(Cu(phen))4(resvan)], was synthesized from the direct reaction of the metals with resorcinarene and generates several possibilities for coordination, which hinders its characterization. Therefore, in order to limit the coordination sites of the ligand, the complex [(Cu(phen))4(resvan)]Cl4 was formed from a new synthetic methodology. The complex cis-[Cu(phen)Cl2], cis-[Cu(phen)(van)]Cl, [(Cu(phen))4(resvan)] and [(Cu(phen))4(resvan)]Cl4 were characterized by spectroscopic techniques such as IR, UV-vis and EPR. By using infrared it has been possible to demonstrate the presence of the phenanthroline ligand in the synthesized complexes, and vanillin in the complex cis- [Cu(phen)(van)]Cl and resvan ligand in the complex [(Cu(phen))4(resvan)], besides this indicating the formation of resorcinarene in the complex [(Cu(phen))4(resvan)]Cl4. The electronic spectra of these coordination compounds indicated the presence of the phenanthroline ligand, by its intense bands in the ultraviolet region. For the complex cis- [Cu(phen)(van)]Cl it still indicated the presence of the ligand vanillin based on intraligand bands of vanillin and charge transfer, LMCT. Furthermore, the spectra showed d-d bands, confirming the formation of metal compounds. The amount of copper atoms present in the complex [(Cu(phen))4(resvan)]Cl4 was estimated from a comparative analysis of the absorbances of solutions of the same concentration of [(Cu(phen))4(resvan)]Cl4 and cis- [Cu(phen)(van)]Cl, which indicates that these compounds have copper atoms in the ratio 4:1. The EPR spectra of the complex cis-[Cu(phen)Cl2], cis-[Cu(phen)(van)]Cl and [(Cu(phen))4(resvan)]Cl4 showed axial profiles, while the complex [(Cu(phen))4(resvan)] showed of axial and rhombic profiles, indicating a change in the symmetry of the Cu (II) to this complex environment. The binders vanillin and resvan underwent biological assays with satisfactory results, both exhibited antioxidant activity and low toxicity, as well vanillin present antitoxoplásmico character.

Estudo de complexos de ferro e de cobre com a base de Shiff 3-Meosalen e ligantes de relevância biológica

The goal set for this work was to synthesize and to characterize new iron and copper complexes with the Schiff base 3-MeOsalen and ligands of biological relevance, whose formulas are [Fe(3-MeOsalen)NO2], [Fe(3-MeOsalen)(etil2-dtc)], [Fe(3-MeOsalen)NO] and Na[Cu(3-MeOsalen)NO2]. The compounds were characterized by vibrational spectroscopy in the infrared region (IV) and Electronic spectroscopy in the ultraviolet and visible region (Uv-Vis). From the analysis of infrared spectra, they proved to formation of precursor complexes, as evidenced by changes in the vibrationals frequencies ν(C=N) e ν(C-O) and the emergence of vibrationals modes metal-oxygen and metal-nitrogen. For nitro complexes of iron and copper were observed ν(NO2)ass around 1300 cm-1 e ν(NO2)sim in 1271 cm-1 , indicating that the coordination is done via the nitrogen atom. The complex spectrum [Fe(3-MeOsalen)(etil2-dtc)] exhibited two bands, the ν(C-NR2) in 1508 cm-1 e ν(C-S) in 997 cm-1 , the relevant vibrational modes of coordinating ligand in the bidentate form. For the complex [Fe(3-MeOsalen)NO] was observed a new intense band in 1670 cm-1 related to the ν(NO). With the electronic spectra, the formation of complexes was evidenced by shifts of bands intraligands transitions and the emergence of new bands such as LMCT (p Cl-  d* Fe3+) in [Fe(3-MeOsalen)Cl] and the d-d in [Cu(3-MeOsalen)H2O]. As for the [Fe(3-MeOsalen)NO2] has highlighted the absence of LMCT band present in the precursor complex as for the [Cu(3-MeOsalen)NO2] found that the displacement of the band hipsocrômico d-d on 28 nm. The electronic spectrum of [Fe(3-MeOsalen)(etil2-dtc)] presented LMCT band shifts and changes in intraligantes transitions. With regard to [Fe(3-MeOsalen)NO], revealed a more energetic transitions intraligands regions from the strong character π receiver NO and MLCT band of transition dπFe(II)π*(NO).

Usos de membranas de quitosana na remoção de cobre em águas residuais

In this work a chitosan (CS) ionically crosslinked were manufactured by treatment with sulfuric acid solution for application in the treatment of wastewater from oil industry. Two crosslinking process were developed: homogeneous and heterogeneous. In the homogeneous process the ratio molar of SO42-/ NH3+ (1:6 and 1:4) were the variable analyzed, denominated CS16 and CS14 respectively. In the heterogeneous process the soaking time of the membranes in sulfuric acid solution were the variable studied, being used times of 5 (CS5) and 30 (CS30) minutes. FTIR-ATR results indicated no changes in the characteristics of chitosan after homogeneous crosslinking process, while heterogeneous crosslinking showed formation of ionic bonds between protonated groups from chitosan and the crosslinking agent sulfate ions. TG/DTG and XRD analysis confirmed the formation of these interactions, as also shown the new structure on the surface region of CS5 and CS30 membranes compared to CS, CS16 e CS14. Swelling test in aqueous medium have shown that crosslinking process reduced the membrane sorption capacity. Swelling test in acid medium demonstrated that CS16 and CS14 membranes increasing the adsorption capacity up to a maximum percentage of 140% approximately, whereas the CS5 e CS30 reached a maximum of 60%. The mechanical properties indicated the stiff and ductile behavior of crosslinked membrane. Adsorption experiments of CuCl2 results that CS16 membranes reached the efficiency maximum with 73% of copper removal at pH 5.0 and 87% at pH 4.0. The experiments with CuSO4 also obtained efficiency maximum to the CS16 membrane and 80% to the removal of Cu2+ ions. Also was verified that the increase of concentration and temperature cause a decrease in the adsorption capacity for all membranes. Kinetics study indicated that pseudo-second-order obtained characterized better the membranes. Equilibrium studies demonstrated that the CS, CS16 and CS14 follow the Langmuir model, whereas CS5 and CS30 follows Freundlich model. Filtration experiments results with rejection maximum to the CS16 and CS5 membranes, reaching 92 and 98% respectively.

Usos de membranas de quitosana na remoção de cobre em águas residuais

In this work a chitosan (CS) ionically crosslinked were manufactured by treatment with sulfuric acid solution for application in the treatment of wastewater from oil industry. Two crosslinking process were developed: homogeneous and heterogeneous. In the homogeneous process the ratio molar of SO42-/ NH3+ (1:6 and 1:4) were the variable analyzed, denominated CS16 and CS14 respectively. In the heterogeneous process the soaking time of the membranes in sulfuric acid solution were the variable studied, being used times of 5 (CS5) and 30 (CS30) minutes. FTIR-ATR results indicated no changes in the characteristics of chitosan after homogeneous crosslinking process, while heterogeneous crosslinking showed formation of ionic bonds between protonated groups from chitosan and the crosslinking agent sulfate ions. TG/DTG and XRD analysis confirmed the formation of these interactions, as also shown the new structure on the surface region of CS5 and CS30 membranes compared to CS, CS16 e CS14. Swelling test in aqueous medium have shown that crosslinking process reduced the membrane sorption capacity. Swelling test in acid medium demonstrated that CS16 and CS14 membranes increasing the adsorption capacity up to a maximum percentage of 140% approximately, whereas the CS5 e CS30 reached a maximum of 60%. The mechanical properties indicated the stiff and ductile behavior of crosslinked membrane. Adsorption experiments of CuCl2 results that CS16 membranes reached the efficiency maximum with 73% of copper removal at pH 5.0 and 87% at pH 4.0. The experiments with CuSO4 also obtained efficiency maximum to the CS16 membrane and 80% to the removal of Cu2+ ions. Also was verified that the increase of concentration and temperature cause a decrease in the adsorption capacity for all membranes. Kinetics study indicated that pseudo-second-order obtained characterized better the membranes. Equilibrium studies demonstrated that the CS, CS16 and CS14 follow the Langmuir model, whereas CS5 and CS30 follows Freundlich model. Filtration experiments results with rejection maximum to the CS16 and CS5 membranes, reaching 92 and 98% respectively.

Verdigrís, pigmento histórico de cobre: estudio de su composición y color a partir de reproducciones de antiguas recetas

Bajo la denominación del verdigrís se incluye una amplia variedad de pigmento de origen sintético cuyo color puede ser verde, verde-azulado o incluso azul. Su proceso de obtención se basa en la corrosión del cobre o sus aleaciones provocada por la acción del ácido acético contenido en el vinagre o por la acción de cloruros (cloruro sódico o cloruro amónico). Ha sido uno de los pigmentos más importantes de la historia y ha sido profusamente utilizado por artistas de todas las épocas y escuelas pictóricas. Sus procesos de obtención se conocen desde la antigüedad clásica, y aparecen recogidos en textos de aquella época y en muchos otros de la época medieval y de los siglos XVI al XIX. Incluso existen patentes de invención de los siglos XIX y XX relacionadas con su obtención y con la propuesta de sistemas para mejorar su producción. Una peculiaridad de este pigmento es su solubilidad en agua, por lo que también ha sido utilizado enla elaboración de tintas que han sido profusamente utilizadas para la elaboración de planos y mapas; en este tipo de usos eran utilizadas para representar las zonas de vegetación o de agua (ríos, lagos, zonas de costa) Son numerosas las investigaciones que se han realizado en torno a este pigmento. Muchas de ellas han estado dirigidas a esclarecer su composición química y aunque son de indudable interés, estas aportaciones no resultan suficientes. La principal razón es que se trata de un pigmento que puede obedecer a una amplia variedad de composiciones; a este respecto han sido identificadas diferentes hidroxiacetatos de cobre(II) hidratados, hidroxicloruros de cobre(II) y acetato de cobre(II) hidratado, entre otros compuestos...

Corrosão das armaduras não estruturais em elementos de betão armado

A corrente dissertação enquadra-se na temática da corrosão das armaduras mais concretamente nas armaduras mínimas, não estruturais e construtivas. É frequente encontrarmos sinais de degradação em estruturas e elementos de betão armado, maioritariamente causado pela corrosão das armaduras. Tais armaduras por vezes não têm solicitações estruturais, desta forma estuda-se a hipótese de as mesmas terem sido dispensadas no momento de conceção da estrutura ou do elemento. Tem-se em conta todos os fatores que podem influenciar a corrosão de forma a entender o seu comportamento, assim como o seu enquadramento legislativo. São inúmeras as causas de corrosão prematura das armaduras, como a elevada porosidade do betão, a utilização dos materiais errados de acordo com o ambiente, o recobrimento insuficiente, entre outros. Contudo o processo de corrosão é provocado apenas pela carbonatação e/ou cloretos existentes no betão que destrói a pelicula passiva das armaduras. Elaborou-se análises em casos mais usuais com degradação acentuada. Assim, apenas analisou-se casos onde a corrosão era visível, uma vez que a análise se baseou apenas na observação visual, e ignorou-se os restantes casos devido á incerteza da existência de corrosão, mesmo em ambientes agressivos. Em todos os casos teve-se em conta o comportamento químico e físico, do betão e das armaduras de forma a compreender as causas da degradação e suas consequências, assim como outros parâmetros como por exemplo a temperatura. Com base nos dois parágrafos anteriores, e com recurso ao levantamento fotográfico de alguns elementos e estruturas de betão armado, analisou-se neste trabalho 8 casos não estruturais e 2 casos estruturais referente à aplicação das armaduras.

Distribución de cobre, plomo, zinc y cadmio en los sedimentos del Puerto del Callao

Los sedimentos marinos son el último recipiente de casi todas las trazas de metales introducidas por la actividad del hombre dentro del ecosistema marino. Los metales son un constituyente común de casi todos los sedimentos y son estudiados como tales, no solamente por sus efectos tóxicos directos si no también como indicadores para evaluar el comportamiento de ciertos desechos.

Determinação de cobre, cromo e arsênio em madeira preservada (Eucalyptus sp.) pelas espectrometrias de fluorescências de raios X

Dissertação (Mestrado em Tecnologia Nuclear)

Análisis de polifenoles en algas: implicación de estos compuestos en mecanismos para disminuir la toxicidad del cobre y regular la disponibilidad del hierro en microalgas

Programa de doctorado: Oceanografía. La fecha de publicación es la fecha de lectura.