The Critical Role of Ligand Flexibility on the Activity of Free and Immobilized Mn Superoxide Dismutase Mimics

Autor: Micaela Richezzi, Sharon Signorella, Claudia Palopoli, Nora Pellegri, Christelle Hureau, Sandra R. Signorella
Jazyk: angličtina
Rok vydání: 2023
Předmět:
Zdroj: Inorganics, Vol 11, Iss 9, p 359 (2023)
Druh dokumentu: article
ISSN: 11090359
2304-6740
DOI: 10.3390/inorganics11090359
Popis: In low-molecular-weight Mn superoxide dismutase (SOD) mimics, the ligand plays a key role in tuning the reactivity of the metal center with O2•−. We used three ligands differing in their donor sites, flexibility and/or charge, to compare the redox properties and SOD activity of the resulting Mn complexes: 1,3-bis[(pyridin-2-ylmethyl)(propargyl)amino]propane (pypapn), 1,3-bis(pyridin-2-ylmethyleneamino)propane (py2pn) and 1,4-bis(salicylidenamino)butane (H2salbn). These ligands afford Mn complexes that, in aqueous solution, exist as mononuclear species [Mn(II)(pypapn)(H2O)2]2+, [Mn(II)(py2pn)(H2O)2]2+ and [Mn(III)(salbn)(H2O)2]+. The relative reactivity of these compounds with O2•− at pH 7.8, [Mn(pypapn)(H2O)2]2+ > [Mn(salbn)(H2O)2]+ > [Mn(py2pn)(H2O)2]2+, is independent of the redox potential but strongly depends on the ligand flexibility which becomes a critical feature when the reaction occurs through an inner-sphere electron-transfer mechanism. Immobilization was used to isolate and protect the catalyst from dissociation or dimerization during catalysis. [Mn(pypapn)(H2O)2]2+, with the alkyne group, was covalently grafted to azide functionalized mesoporous silica through click chemistry, while [Mn(py2pn)(solv)2]2+ and [Mn(salbn)(solv)2]+ were encapsulated in SBA-15 mesoporous silica through ionic exchange. The retention or enhancement of the SOD activity and the improved stability of the covalently attached catalyst and the doubly charged complex encapsulated in the silica pores, make them suitable for use in aqueous media.
Databáze: Directory of Open Access Journals
Externí odkaz:
Nepřihlášeným uživatelům se plný text nezobrazuje