{"database":"biostudies-literature","file_versions":[],"scores":null,"additional":{"omics_type":["Unknown"],"volume":["10(46)"],"submitter":["Frey ST"],"pubmed_abstract":["A series of six Mn<sup>2+</sup> complexes of pyridine-containing, tripodal ligands were investigated in this study to examine the effect of varying ligand N and O donor content on their structural, aqueous stability and superoxide dismutase (SOD) activity. Crystalline forms of the complexes of the formula [MnL-(OAc)-(MeOH)]-BPh<sub>4</sub>, where L is a tripodal ligand, were characterized by IR, elemental analysis, and X-ray diffraction. Crystal structures of each compound reveal a hepta-coordinated Mn<sup>2+</sup> ion with distorted pentagonal bipyramidal geometry. Complex formation in aqueous solution was examined by potentiometric titration and cyclic voltammetry. Mn<sup>2+</sup>-binding affinities (log β) of the ligands are strongly influenced by the N and O donor content of the ligands, with greater N content resulting in higher stability. Reduction potentials, <i>E</i> <sub>1/2</sub> Mn-(III/II) of the complexes also correlate to the N and O donor content of the ligands, with lower O content producing higher <i>E</i> <sub>1/2</sub> values. The aqueous complexes catalyze the efficient disproportionation of superoxide ion, where the apparent catalytic rate constants (<i>k</i> <sub>cat</sub>) are influenced by the nature of the O-donor moiety (-OH vs -OCH<sub>3</sub>). For complexes with methoxy-containing ligands, increasing -OCH<sub>3</sub> content correlates negatively with <i>k</i> <sub>cat</sub> values. The opposite trend is observed for complexes with hydroxy-containing ligands, suggesting the role of hydrogen bonding and/or proton transfer by -OH groups in the catalytic mechanism of these complexes."],"journal":["ACS omega"],"pagination":["56817-56829"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC12658643"],"repository":["biostudies-literature"],"pubmed_title":["Effects of Ligand N and O Donor Content on the Structure, Aqueous Stability, and SOD Activity of a Series of Mn&lt;sup&gt;2+&lt;/sup&gt; Complexes with Pyridine-Containing Tripodal Ligands."],"pmcid":["PMC12658643"],"pubmed_authors":["Frey ST","Cirka HA","Frey IT","Bonitatibus PJ","Ballot JG","Stamps AJ","Spengler A","Hale JR","Phalkun NN","Ruan H","Rinaolo KC","Mirkovic A","Frey SJ","Lin H","Nakagawa Y"],"additional_accession":[]},"is_claimable":false,"name":"Effects of Ligand N and O Donor Content on the Structure, Aqueous Stability, and SOD Activity of a Series of Mn&lt;sup&gt;2+&lt;/sup&gt; Complexes with Pyridine-Containing Tripodal Ligands.","description":"A series of six Mn<sup>2+</sup> complexes of pyridine-containing, tripodal ligands were investigated in this study to examine the effect of varying ligand N and O donor content on their structural, aqueous stability and superoxide dismutase (SOD) activity. Crystalline forms of the complexes of the formula [MnL-(OAc)-(MeOH)]-BPh<sub>4</sub>, where L is a tripodal ligand, were characterized by IR, elemental analysis, and X-ray diffraction. Crystal structures of each compound reveal a hepta-coordinated Mn<sup>2+</sup> ion with distorted pentagonal bipyramidal geometry. Complex formation in aqueous solution was examined by potentiometric titration and cyclic voltammetry. Mn<sup>2+</sup>-binding affinities (log β) of the ligands are strongly influenced by the N and O donor content of the ligands, with greater N content resulting in higher stability. Reduction potentials, <i>E</i> <sub>1/2</sub> Mn-(III/II) of the complexes also correlate to the N and O donor content of the ligands, with lower O content producing higher <i>E</i> <sub>1/2</sub> values. The aqueous complexes catalyze the efficient disproportionation of superoxide ion, where the apparent catalytic rate constants (<i>k</i> <sub>cat</sub>) are influenced by the nature of the O-donor moiety (-OH vs -OCH<sub>3</sub>). For complexes with methoxy-containing ligands, increasing -OCH<sub>3</sub> content correlates negatively with <i>k</i> <sub>cat</sub> values. The opposite trend is observed for complexes with hydroxy-containing ligands, suggesting the role of hydrogen bonding and/or proton transfer by -OH groups in the catalytic mechanism of these complexes.","dates":{"release":"2025-01-01T00:00:00Z","publication":"2025 Nov","modification":"2026-06-05T21:17:31.37Z","creation":"2026-05-21T03:13:20.493Z"},"accession":"S-EPMC12658643","cross_references":{"pubmed":["41322613"],"doi":["10.1021/acsomega.5c10215"]}}