Costa Rafael O, Ferreira Sarah S, Pereira Crystiane A, Harmer Jeffrey R, Noble Christopher J, Schenk Gerhard, Franco Roberto W A, Resende Jackson A L C, Comba Peter, Roberts Asha E, Fernandes Christiane, Horn Adolfo
Laboratório de Ciências Químicas, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brazil.
Instituto Federal Fluminese, Campos dos Goytacazes, Brazil.
Front Chem. 2018 Nov 5;6:491. doi: 10.3389/fchem.2018.00491. eCollection 2018.
The synthesis, X-ray molecular structure, physico-chemical characterization and dual antioxidant activity (catalase and superoxide dismutase) of a new polymeric mixed valence Mn(III)Mn(II) complex, containing the ligand HBPClNOL (N-(2-hydroxybenzyl)-N-(2-pyridylmethyl)[(3-chloro)(2-hydroxy)] propylamine) is described. The monomeric unit is composed of a dinuclear Mn(II)Mn(III) moiety, Mn(III)(μ-HBPClNOL)(μ-BPClNOL)Mn(II)(Cl)·2HO, , in which the Mn ions are connected by two different bridging groups provided by two molecules of the ligand HBPClNOL, a phenoxide and an alkoxide group. In the solid state, this mixed valence dinuclear unit is connected to its neighbors through chloro bridges. Magnetic measurements indicated the presence of ferromagnetic [ = +0.076(13) cm] and antiferromagnetic [ = -5.224(13) cm] interactions. The compound promotes O dismutation in aqueous solution (IC = 0.370 μmol dm, = 3.6x10 M s). EPR studies revealed that a high-valent Mn(III)-O-Mn(IV) species is involved in the superoxide dismutation catalytic cycle. Complex shows catalase activity only in the presence of a base, e.g., piperazine or triethylamine. Kinetic studies were carried out in the presence of piperazine and employing two different methods, resulting in values of 0.58 ± 0.03 s (detection of O production employing a Clark electrode) and 2.59 ± 0.12 s (HO consuption recorded via UV-Vis). EPR and ESI-(+)-MS studies indicate that piperazine induces the oxidation of , resulting in the formation of the catalytically active Mn(III)-O-Mn(IV) species.
描述了一种新型聚合物混合价态Mn(III)Mn(II)配合物的合成、X射线分子结构、物理化学表征及双重抗氧化活性（过氧化氢酶和超氧化物歧化酶），该配合物含有配体HBPClNOL（N-(2-羟基苄基)-N-(2-吡啶甲基)[(3-氯)(2-羟基)]丙胺）。单体单元由双核Mn(II)Mn(III)部分Mn(III)(μ-HBPClNOL)(μ-BPClNOL)Mn(II)(Cl)·2HO组成，其中Mn离子通过配体HBPClNOL的两个分子提供的两个不同桥连基团（一个酚氧基和一个醇氧基）相连。在固态下，这种混合价双核单元通过氯桥与其相邻单元相连。磁性测量表明存在铁磁相互作用[J = +0.076(13) cm⁻¹]和反铁磁相互作用[J = -5.224(13) cm⁻¹]。该化合物在水溶液中促进O₂歧化（IC₅₀ = 0.370 μmol dm⁻³，k = 3.6x10⁻⁵ M⁻¹ s⁻¹）。电子顺磁共振（EPR）研究表明，高价Mn(III)-O-Mn(IV)物种参与超氧化物歧化催化循环。配合物仅在碱（如哌嗪或三乙胺）存在下显示过氧化氢酶活性。在哌嗪存在下采用两种不同方法进行了动力学研究，得到的k值分别为0.58 ± 0.03 s⁻¹（使用克拉克电极检测O₂产生）和2.59 ± 0.12 s⁻¹（通过紫外可见光谱记录H₂O₂消耗）。EPR和电喷雾电离(+)-质谱（ESI-(+)-MS）研究表明，哌嗪诱导[配合物]氧化，导致形成催化活性的Mn(III)-O-Mn(IV)物种。
