Insights into Second-Sphere effects on redox potentials, spectroscopic properties, and superoxide dismutase activity of manganese complexes with Schiff-Base Ligands

Six Mn-Schiff base complexes, [Mn(X-salpn)]0/+ (salpn = 1,3-bis(sal-ic-ylidenamino)propane, X = H [1], 5-Cl [2], 2,5-F2 [3], 3,5- Cl2 [4], 5-NO2 [5], 3,5-(NO2)2 [6]), were synthesized and characterized in solution, and second-sphere effects on their electrochemical and spectroscopic properties w...

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Autores principales: Palopoli, Claudia, Ferreyra, Joaquín, Conte-Daban, Amandine, Foi, Ana, Doctorovich, Fabio, Anxolabehére-Mallart, Elodie, Hureau, Christelle, Signorella, Sandra R.
Formato: article artículo publishedVersion
Lenguaje:Inglés
Publicado: ACS 2020
Materias:
Redox reactions
Ligands
Substituents
Transition metals
Electron paramagnetic resonance spectroscopy
Acceso en línea:http://hdl.handle.net/2133/19480
http://hdl.handle.net/2133/19480
Aporte de:
Repositorio Hipermedial de la Universidad Nacional de Rosario (UNR) de Universidad Nacional de Rosario
id I15-R121-2133-19480
record_format dspace
institution Universidad Nacional de Rosario
institution_str I-15
repository_str R-121
collection Repositorio Hipermedial de la Universidad Nacional de Rosario (UNR)
language Inglés
orig_language_str_mv eng
topic Redox reactions
Ligands
Substituents
Transition metals
Electron paramagnetic resonance spectroscopy
spellingShingle Redox reactions
Ligands
Substituents
Transition metals
Electron paramagnetic resonance spectroscopy
Palopoli, Claudia
Ferreyra, Joaquín
Conte-Daban, Amandine
Foi, Ana
Doctorovich, Fabio
Anxolabehére-Mallart, Elodie
Hureau, Christelle
Signorella, Sandra R.
Insights into Second-Sphere effects on redox potentials, spectroscopic properties, and superoxide dismutase activity of manganese complexes with Schiff-Base Ligands
topic_facet Redox reactions
Ligands
Substituents
Transition metals
Electron paramagnetic resonance spectroscopy
description Six Mn-Schiff base complexes, [Mn(X-salpn)]0/+ (salpn = 1,3-bis(sal-ic-ylidenamino)propane, X = H [1], 5-Cl [2], 2,5-F2 [3], 3,5- Cl2 [4], 5-NO2 [5], 3,5-(NO2)2 [6]), were synthesized and characterized in solution, and second-sphere effects on their electrochemical and spectroscopic properties were analyzed. The six complexes catalyze the dismutation of superoxide with catalytic rate constants in the range 0.65 to 1.54 × 106 M−1 s −1 obtained through the nitro blue tetrazolium photoreduction inhibition superoxide dismutases assay, in aqueous medium of pH 7.8. In solution, these compounds possess two labile solvent molecules in the axial positions favoring coordination of the highly nucleophilic O2 •− to the metal center. Even complex 5, [Mn(5- (NO2)salpn) (OAc) (H2O)], with an axial acetate in the solid state, behaves as a 1:1 electrolyte in methanolic solution. Electron paramagnetic resonance and UV−vis monitoring of the reaction of [Mn(X-salpn)]0/+ with KO2 demonstrates that in diluted solutions these complexes behave as catalysts supporting several additions of excess O2 •−, but at high complex concentrations (≥0.75 mM) catalyst self-inhibition occurs by the formation of a catalytically inactive dimer. The correlation of spectroscopic, electrochemical, and kinetics data suggest that second-sphere effects control the oxidation states of Mn involved in the O2 •− dismutation cycle catalyzed by complexes 1−6 and modulate the strength of the Mn-substrate adduct for electron-transfer through an inner-sphere mechanism.
format article
artículo
publishedVersion
author Palopoli, Claudia
Ferreyra, Joaquín
Conte-Daban, Amandine
Foi, Ana
Doctorovich, Fabio
Anxolabehére-Mallart, Elodie
Hureau, Christelle
Signorella, Sandra R.
author_facet Palopoli, Claudia
Ferreyra, Joaquín
Conte-Daban, Amandine
Foi, Ana
Doctorovich, Fabio
Anxolabehére-Mallart, Elodie
Hureau, Christelle
Signorella, Sandra R.
author_sort Palopoli, Claudia
title Insights into Second-Sphere effects on redox potentials, spectroscopic properties, and superoxide dismutase activity of manganese complexes with Schiff-Base Ligands
title_short Insights into Second-Sphere effects on redox potentials, spectroscopic properties, and superoxide dismutase activity of manganese complexes with Schiff-Base Ligands
title_full Insights into Second-Sphere effects on redox potentials, spectroscopic properties, and superoxide dismutase activity of manganese complexes with Schiff-Base Ligands
title_fullStr Insights into Second-Sphere effects on redox potentials, spectroscopic properties, and superoxide dismutase activity of manganese complexes with Schiff-Base Ligands
title_full_unstemmed Insights into Second-Sphere effects on redox potentials, spectroscopic properties, and superoxide dismutase activity of manganese complexes with Schiff-Base Ligands
title_sort insights into second-sphere effects on redox potentials, spectroscopic properties, and superoxide dismutase activity of manganese complexes with schiff-base ligands
publisher ACS
publishDate 2020
url http://hdl.handle.net/2133/19480
http://hdl.handle.net/2133/19480
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