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Start Over Author "Piro, Oscar" Publisher elsevier b.v.
130 results on '"Piro, Oscar"'

48. Superoxidedismutase-mimetic copper(II) complexes containing saccharinate and 4-aminopyridine/4-cyanopyridine.

Author

Ferrer, Evelina G., Baeza, Natalia, Naso, Luciana G., Castellano, Eduardo E., Piro, Oscar E., and Williams, Patricia A.M.

Subjects
SUPEROXIDE dismutase, METAL complexes, COPPER compounds, COMPLEX compounds synthesis, AMINOPYRIDINES, X-ray diffraction, INFRARED spectroscopy, CRYSTALLOGRAPHY
Abstract

Abstract: Two copper(II) complexes, [Cu(sac)2(4-cypy)2(H2O)], 1 and [Cu(sac)2(4-Ampy)2(H2O)], 2 (4-cypy: 4-cyanopyridine; 4-Ampy: 4-aminopyridine) were prepared. Physicochemical properties of the complexes were studied by spectroscopic (solution UV–vis, diffuse reflectance and IR) techniques. Structural X-ray diffraction data could be obtained only for [Cu(sac)2(4-cypy)2(H2O)] that it crystallized in the tetragonal space group P4cc with a=b=15.313(1), c=13.240(1)Å, and Z=4 molecules per unit cell. The complex was cited on a crystallographic C 2-axis with the Cu(II) ion in a square–pyramidal environment, coordinated at the pyramid basis to the nitrogen atom of two saccharine anions [d(Cu–N)=2.011(3)Å] and the pyridine N-atom of two 4-cyanopyridine ligands [d(Cu–N)=2.038(4)Å]. The coordination was completed by a water molecule at the pyramid apex [d(Cu–Ow)=2.189(5)Å]. Elemental and spectroscopic analyses revealed an O-saccharinate coordination mode for complex 2 and a square–pyramidal structure. Only complex 2 retained its structure in methanolic solution. However, both complexes were able to catalyze the dismutation of superoxide anion (O2 −) (pH 7.5) at micromolar concentrations. Therefore, these complexes behaved as useful SOD-mimetic compounds. [Copyright &y& Elsevier]

Published
2010
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49. Structure of indazole N 1-oxide derivatives studied by X-ray, theoretical methods, 1H, 13C, 15N NMR and EI/MS

Author

Gerpe, Alejandra, Piro, Oscar E., Cerecetto, Hugo, and González, Mercedes

Subjects
*MOLECULAR structure, *NITROGEN oxides, *X-ray crystallography, *NONMETALS
Abstract

Abstract: A series of indazole N 1-oxide derivatives has been spectroscopically studied in solution using 1H, 13C, and 15N NMR based on pulsed field gradient selected PFG 1Hsp sp="0.25" />= 13C and 15N) gHMQC and gHMBC experiments. Some indazoles were prepared using a new methodology to compare its spectral and structural data with the indazole N 1-oxide parent compounds. The 13C resonances of the indazole N 1-oxide carbon 3 and 7a demonstrate the N-oxide push-electron capability. The 15N resonances of the indazole N-oxide, nitrogen 1, are near to 30ppm more shielded than the corresponding values in the indazole heterocycle (deoxygenated form). Moreover, the structures of one indazole and one indazole N-oxide were unambiguously confirmed by X-ray crystallography. The solid state structures were contrasted with the theoretical ones obtained in vacuo at different calculus level. The aromaticity of the derivatives was studied analyzing the Hg constants of indazole’s aromatic hydrogens and measuring Ces in the solid state. The fragmentation that takes place in EI/MS was gathered for all the indazole N-oxide derivatives and the general fragmentation pattern analyzed. [Copyright &y& Elsevier]

Published
2007
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50. Crystal structures, spectroscopic characterization and theoretical calculations of the guanidinium and ammonium salts of the insulin-enhancing anion [VO2(dipic)]−

Author

Parajón-Costa, Beatriz S., Piro, Oscar E., Pis-Diez, Reinaldo, Castellano, Eduardo E., and González-Baró, Ana C.

Subjects
*HYPOGLYCEMIC agents, *INFRARED spectroscopy, *COORDINATION compounds, *COMPLEX compounds
Abstract

Abstract: The novel complex, C(NH2)3[VO2(dipic)]·2H2O (1), and its analogous, NH4[VO2(dipic)] (2), were synthesized and characterized in the solid state by means of FT-Raman and FT-infrared spectroscopies. Their crystal and molecular structures were determined by X-ray diffraction methods. The optimized geometry of the [VO2(dipic)]− anion and its corresponding harmonic vibrational frequencies were calculated using methods of the density functional theory. The [VO2(dipic)]− anion in both salts show a similar penta-coordinated environment. The planar dipic2− ligand coordinates to the moiety through one oxygen of each carboxylate and the nitrogen atom. Slight but significant differences between the bonding structures in both compounds were observed. The crystal structures are stabilized by hydrogen bridging interactions. [Copyright &y& Elsevier]

Published
2006
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