Spectroscopic and computational studies of a small-molecule functional mimic of iron superoxide dismutase, iron 2,6-diacetylpyridinebis(semioxamazide).
Spectroscopic and computational studies of a small-molecule functional mimic of iron superoxide dismutase, iron 2,6-diacetylpyridinebis(semioxamazide).
复制标题
铁超氧化物歧化酶小分子功能模拟物铁 2,6-二乙酰吡啶双（半恶嗪）的光谱和计算研究。
DOI：
10.1021/ic301547z
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发表时间：
2012
影响因子：
4.6
通讯作者：
Brunold,ThomasC
中科院分区：
文献类型：
--
作者：
Gutman,CraigT;Brunold,ThomasC
铁2，6-diacetylpyridinebis（semioxamazide）（Fe（dapsox））是一个七配位五角双锥体，铁依赖性超氧化物歧化酶的功能模拟物，其特征在于动力学和机理研究的基础上，然而，在我们的研究之前，其电子结构尚未被检查。本文详细介绍了我们的初步表征铁（dapsox）在其还原和氧化状态，电子吸收（Abs）和低温磁圆二色光谱。密度泛函理论（DFT）的几何优化产生了良好的协议与公布的晶体结构模型。对这些模型进行的时间依赖性DFT和INDO/S-CI计算成功地再现了实验Abs光谱，并将还原络合物（Fe II（H2 dapsox））中的强烈低能跃迁识别为金属-配体电荷转移跃迁，表明该络合物中存在π-背键。这种背键结合，沿着，伴随着金属离子还原的质子吸收，提供了一个令人信服的机制，通过该机制，金属为中心的氧化还原电位被正确地调整为催化超氧化物歧化。
Iron 2,6-diacetylpyridinebis(semioxamazide) (Fe(dapsox)) is a heptacoordinate pentagonal bipyramidal, functional mimic of iron-dependent superoxide dismutase that has been well-characterized on the basis of kinetics and mechanistic studies; however, prior to our studies, its electronic structure had yet to be examined. This paper details our initial characterization of Fe(dapsox) in both its reduced and oxidized states, by electronic absorption (Abs) and low-temperature magnetic circular dichroism spectroscopies. Density functional theory (DFT) geometry optimizations have yielded models in good agreement with the published crystal structures. Time-dependent DFT and INDO/S-CI calculations performed on these models successfully reproduce the experimental Abs spectra and identify intense, low-energy transitions in the reduced complex (FeII(H2dapsox)) as metal-to-ligand charge transfer transitions, suggesting the presence of π-backbonding in this complex. This backbonding, along, with the proton uptake accompanying metal ion reduction, provides a compelling mechanism by which the metal-centered redox potential is correctly tuned for catalytic superoxide disproportionation.