Novel organotin and organotellurium complexes : building blocks for new materials?

The research produced a series of novel oranotin and organotellurium compounds that are potential building blocks for new materials. In particular, one carbonate cluster has practical applications in the fixation and recovery of carbon dioxide gas from the atmosphere.

Hormonal breast and prostate cancer cytotoxic agents

Details 13 novel hormone compounds, designed and synthesised for the purpose of aiding the detection and treatment of breast and prostate cancers. Cellular and electromechanical studies of 3 of these synthesised hormones indicate a potential for human application.

Electrooxidation of [(η5-C5H5)Fe(CO)2]2 as a probe of the nucleophilic properties of ionic liquid anions

The oxidative electrochemistry of [CpFe(CO)2]2, 1 (Cp = [η5-C5H5]–), was examined in detail in ionic liquids (ILs) composed of ions of widely varying Lewis acid−base properties. Cyclic voltammetric responses were strongly dependent on the nucleophilic properties of the IL anion, but all observations are consistent with the initial formation of 1+ followed by attack from the IL anion. In [NTf2]–-based ILs ([NTf2]– = bis(trifluoromethylsulfonyl)amide), the process shows nearly ideal chemical reversibility as the reaction between 1+ and [NTf2]– is very slow. This is highly significant, as 1+ is known to be highly susceptible to nucleophilic attack and its stability indicates a remarkable lack of coordinating ability of these ILs. In 1-methyl-3-butylimidazolium hexafluorophosphate, [bmim][PF6], the oxidation of 1 is still largely reversible, but there is more pronounced evidence of [PF6]– coordination. In contrast, 1 exhibits an irreversible two-electron oxidation process in a dicyanamide-based IL. This overall oxidation process is thought to proceed via an ECE mechanism, details of which are presented. Rate constants were estimated by fitting the experimental data to digital simulations of the proposed mechanism. The use of [NTf2]–-based ILs as a supporting electrolyte in CH2Cl2 was examined by using this solvent/electrolyte as a medium in which to perform bulk electrolyses of 1 and 1*, the permethylated analogue [Cp*Fe(CO)2]2 (Cp* = [η5-C5(CH3)5]–). These cleanly yielded the corresponding binuclear radical-cation species, 1+ and 1*+, which were subsequently characterized by electron paramagnetic resonance (EPR) spectroscopy. In addition to the above oxidation studies, the reduction of 1 was studied in each of the ILs; differences in cathodic peak potentials are attributed, in part, to ion-pairing effects. This study illustrates the wide range of electrochemical environments available with ILs and demonstrates their utility for the investigation of the redox properties of metal carbonyls and other organometallic compounds.

Analysis of 177Lu-octreotate therapy-induced DNA damage in peripheral blood lymphocytes of patients with neuroendocrine tumors

Ionizing radiation (IR)-induced DNA double-strand breaks (DSBs) can lead to cell death, genome instability and carcinogenesis. Immunofluorescence detection of phosphorylated histone variant H2AX (γ-H2AX) is a reliable and sensitive technique to monitor external beam IR-induced DSBs in peripheral blood lymphocytes (PBL). Here, we investigated whether γ-H2AX could be used as an in vivo marker to assess normal tissue toxicity after extended internal irradiation with (177)Lu-DOTA-octreotate peptide receptor radionuclide therapy (LuTate PRRT) of neuroendocrine tumors.

Oral treatment with Cu(II)(atsm) increases mutant SOD1 in vivo but protects motor neurons and improves the phenotype of a transgenic mouse model of amyotrophic lateral sclerosis

Mutations in the metallo-protein Cu/Zn-superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS) in humans and an expression level-dependent phenotype in transgenic rodents. We show that oral treatment with the therapeutic agent diacetyl-bis(4-methylthiosemicarbazonato)copper(II) [Cu(II)(atsm)] increased the concentration of mutant SOD1 (SOD1G37R) in ALS model mice, but paradoxically improved locomotor function and survival of the mice. To determine why the mice with increased levels of mutant SOD1 had an improved phenotype, we analyzed tissues by mass spectrometry. These analyses revealed most SOD1 in the spinal cord tissue of the SOD1G37R mice was Cu deficient. Treating with Cu(II)(atsm) decreased the pool of Cu-deficient SOD1 and increased the pool of fully metallated (holo) SOD1. Tracking isotopically enriched (65)Cu(II)(atsm) confirmed the increase in holo-SOD1 involved transfer of Cu from Cu(II)(atsm) to SOD1, suggesting the improved locomotor function and survival of the Cu(II)(atsm)-treated SOD1G37R mice involved, at least in part, the ability of the compound to improve the Cu content of the mutant SOD1. This was supported by improved survival of SOD1G37R mice that expressed the human gene for the Cu uptake protein CTR1. Improving the metal content of mutant SOD1 in vivo with Cu(II)(atsm) did not decrease levels of misfolded SOD1. These outcomes indicate the metal content of SOD1 may be a greater determinant of the toxicity of the protein in mutant SOD1-associated forms of ALS than the mutations themselves. Improving the metal content of SOD1 therefore represents a valid therapeutic strategy for treating ALS caused by SOD1.

Magnetic susceptibility of an exactly solvable anisotropic spin ladder system

We investigate the thermodynamics of an integrable spin ladder model which possesses a free parameter besides rung and leg couplings. The model is exactly solvable by means of the Bethe ansatz and exhibits a phase transition between a gapped and a gapless spin excitation spectrum. The magnetic susceptibility is obtained numerically and its dependence on the anisotropy parameter is determined. The spin gap obtained from the susceptibility curve and the one obtained from the Bethe ansatz equations are in very good agreement. Our results for the magnetic susceptibility fit well the experimental data for the organometallic compounds (5IAP)(2)CuBr4 . 2H(2)O (Landee C. P. et al., Phys. Rev. B, 63 (2001) 100402(R)) Cu-2(C5H12N2)(2)Cl-4 (Hayward C. A., Poilblanc D. and Levy L. P., Phys. Rev. B, 54 (1996) R12649, Chaboussant G. et al., Phys. Rev. Lett., 19 ( 1997) 925; Phys. Rev. B, 55 ( 1997) 3046.) and (C5H12N)(2)CuBr4 (Watson B. C. et al., Phys. Rev. Lett., 86 ( 2001) 5168) in the strong-coupling regime.

Ressonância paramagnética eletrônica (RPE) aplicada em semicondutores orgânicos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Intoxicação alimentar por metilmercúrio em tilápia do Nilo e sua biomagnificação em ratos wistar

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Síntese e caractrização de nanopartículas magnéticas do tipo caroço@casca de 'CO'@'PD' com propriedades para aplicações tecnológicas

Pós-graduação em Química - IQ

Espécies metalo-supramoleculares discretas polinucleares: sínteses e caracterização

Pós-graduação em Química - IQ

Light-Induced Structural Change in Iridium Complexes Studied by Electron Spin Resonance

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Sensores eletroquímicos à base de nanomateriais carbonáceos e catalisadores biomiméticos para determinação de tetraciclina em diferentes tipos de amostras

Pós-graduação em Química - IQ

Síntese, caracterização e atividade catalítica de compostos organolantanídeos contendo os ânions metanossulfonato e pentametilciclopentadienil e o ligante pirazinamida

O estudo de compostos organolantanídeos consiste em um dos campos de maior interesse dentro da química organometálica, principalmente devido ao uso potencial como precursores ou catalisadores em reações de hidrogenação, hidroformilação, carbonilação, oxidação e principalmente polimerização de olefinas. Este interesse tem levado diversos grupos de pesquisa a sintetizarem compostos utilizando o ânion ciclopentadienil e seus derivados ligados a íons lantanídeos (III). O presente trabalho tem como objetivo contribuir para a aplicação desses compostos organolantanídeos como catalisadores em reações de polimerização de olefinas. O trabalho envolveu uma etapa de síntese e caracterização de duas classes de compostos organolantanídeos Ln(MS)2Cp*(Ln = Tb e Yb), e Ln(MS)2Cp*PzA (Ln = Sm, Tb e Yb) e uma etapa de estudo da atividade catalítica desses compostos frente a reações de polimerização de etileno, propileno e estireno, utilizando metilaluminoxano como co-catalisador e a caracterização dos polímeros formados. Os compostos sintetizados apresentaram atividade catalítica apenas para polimerização de estireno. O polímero formado, independente do composto organolantanídeo utilizado, foi caracterizado como poliestireno principalmente atático, indicando que a polimerização não é estereoespecífica e apresentou massa molar da ordem de 104 g/mol.