Exchange interactions in the coper(II)-N-benzoylglycine (hippuric acid) complex

O complexo CuII-N-benzoilglicina provê um sistema conveniente para se estudar interações de troca fracas entre elétrons desemparelhados que são transmitidas por caminhos químicos de interesse biológico. A molécula existe como um dímero onde cada CuII está coordenado a cinco ligantes, formando uma pirâmide de base quadrada distorcida. O único caminho químico entre íons CuII magneticamente não-equivalentes envolve 17 átomos diamagnéticos e uma fraca ligação de hidrogênio putativa. Esta interação foi estudada por Ressonância Paramagnética Eletrônica de amostras monocristalinas a 9,5 e 34,5 GHz, tendo sua magnitude sido calculada em 4(1) mK. Esse valor é discutido em termos de valores obtidos para caminhos similares em outros compostos-modelo e proteínas.The complex CuII-N-benzoylglycine provides a convenient system to study weak exchange interactions between unpaired spins transmitted through a biologically relevant long chemical bridge. The molecule exists as a dimer with each CuII ion coordinated to five ligands, forming a distorted square–based pyramid. The only chemical connection between magnetically non-equivalent copper ions is a very long path comprising 17 diamagnetic atoms and a weak putative hydrogen bond. This interaction was studied using Electron Paramagnetic Resonance in single-crystal samples at 9.5 and 34.5 GHz and its magnitude was calculated as 4(1) mK. This value is discussed in terms of values obtained for similar paths in other model compounds and in proteins.CNPq (307102/2006-8)FAPESPCAPESFINEPPRONEX/FAPESP/CNPq (03/09859-2

Ferromagnetic resonance for the quantification of superparamagnetic iron oxide nanoparticles in biological materials

The aim of the present work is the presentation of a quantification methodology for the control of the amount of superparamagnetic iron oxide nanoparticles (SPIONs) administered in biological materials by means of the ferromagnetic resonance technique (FMR) applied to studies both in vivo and in vitro. The in vivo study consisted in the analysis of the elimination and biodistribution kinetics of SPIONs after intravenous administration in Wistar rats. The results were corroborated by X-ray fluorescence. For the in vitro study, a quantitative analysis of the concentration of SPIONs bound to the specific AC133 monoclonal antibodies was carried out in order to detect the expression of the antigenic epitopes (CD133) in stem cells from human umbilical cord blood. In both studies FMR has proven to be an efficient technique for the SPIONs quantification per volume unit (in vivo) or per labeled cell (in vitro)

Research of new mixed-chelate copper complexes with Quinoxaline N1,N4-dioxide derivatives and Alanine as ligands, potential antimycobacterial agents

Three new mixed-chelate copper complexes with 3-aminoquinoxaline-2-carbonitrile N1,N4-dioxide derivatives and alanine as ligands were synthesized in solid state. The spectroscopic characterization (FTIR, EPR, UV-Vis) showed that copper coordinated through the amine and the N-oxide groups of the quinoxaline derivatives and the amine and carboxylate moieties from alanine forming a dimeric species. The tree complexes showed in vitro activity against M. tuberculosis H37Rv (ATCC 27294) similar to that of ethambutol while they are inactive against E. coli and S. aureus.Tres nuevos complejos mixtos de cobre con derivados de 3-aminoquinoxalina-2-carbonitrilo N1,N4-dióxido y alanina como ligandos fueron sintetizados en estado sólido. La caracterización espectroscópica (FTIR, EPR, UV-Vis) mostró que el Cu coordina con el grupo amino y el N-óxido del derivado quinoxalínico y con el amino y el carboxilato de la alanina formando especies diméricas. Los tres complejos mostraron actividad frente al M. tuberculosis H37Rv (ATCC 27294) similar a la del etambutol, mientras que fueron inactivos frente a E. coli y S. aureus.PEDECIB

Research of new mixed-chelate copper complexes with quinoxaline N 1,N 4,-dioxide derivatives and alanine as ligands, potential antimycobacterial agents

Three new mixed-chelate copper complexes with 3-aminoquinoxaline-2-carbonitrile N 1,N 4-dioxide derivatives and alanine as ligands were synthesized in solid state. The spectroscopic characterization (FTIR, EPR, UV-Vis) showed that copper coordinated through the amine and the N-oxide groups of the quinoxaline derivatives and the amine and carboxylate moieties from alanine forming a dimeric species. The tree complexes showed in vitro activity against M. tuberculosis H 37Rv (ATCC 27294) similar to that of ethambutol while they are inactive against E. coli and S. aureus