Watching Excited State Dynamics with Optical and X-ray Probes: The Excited State Dynamics of Aquocobalamin and Hydroxocobalamin
Watching Excited State Dynamics with Optical and X-ray Probes: The Excited State Dynamics of Aquocobalamin and Hydroxocobalamin
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使用光学和 X 射线探针观察激发态动力学：水钴胺和羟钴胺的激发态动力学
DOI：
10.1021/jacs.3c04099
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发表时间：
2023
影响因子：
15
通讯作者：
Deb, Aniruddha
中科院分区：
文献类型：
--
作者：
Sension, Roseanne J.;McClain, Taylor P.;Lamb, Ryan M.;Alonso-Mori, Roberto;Lima, Frederico Alves;Ardana-Lamas, Fernando;Biednov, Mykola;Chollet, Matthieu;Chung, Taewon;Deb, Aniruddha
结合Co k边飞秒时间分辨x射线吸收（XANES）、Co Kβ和价核区x射线发射（XES）和宽带紫外-可见瞬态吸收，探测光激发后两种维生素B12化合物氢钴胺素和水钴胺素的飞秒到皮秒顺序原子和电子动力学。偏振XANES差异光谱允许识别顺序结构演化，首先涉及赤道配体，然后是轴向配体，后者显示出快速的相干键延伸到激发态电位的外部转折点，然后反冲到松弛激发态结构。时间分辨的x，特别是在价核区，以及偏振光学瞬态吸收表明，反冲导致金属中心激发态的形成，其寿命为2-5 ps。这种方法的组合为探测光活性过渡金属配合物的电子和结构动力学提供了独特的强大工具，并将适用于各种系统。
Femtosecond time-resolved X-ray absorption (XANES) at the Co K-edge, X-ray emission (XES) in the Co Kβ and valence-to-core regions, and broadband UV–vis transient absorption are combined to probe the femtosecond to picosecond sequential atomic and electronic dynamics following photoexcitation of two vitamin B12 compounds, hydroxocobalamin and aquocobalamin. Polarized XANES difference spectra allow identification of sequential structural evolution involving first the equatorial and then the axial ligands, with the latter showing rapid coherent bond elongation to the outer turning point of the excited state potential followed by recoil to a relaxed excited state structure. Time-resolved XES, especially in the valence-to-core region, along with polarized optical transient absorption suggests that the recoil results in the formation of a metal-centered excited state with a lifetime of 2–5 ps. This combination of methods provides a uniquely powerful tool to probe the electronic and structural dynamics of photoactive transition-metal complexes and will be applicable to a wide variety of systems.