微量液滴中的抗维生素B：利用瞬态偏振X射线吸收近边结构研究珍贵样品的激发态结构
Antivitamins B in a Microdrop: The Excited-State Structure of a Precious Sample Using Transient Polarized X-ray Absorption Near-Edge Structure.
作者信息
Miller Nicholas A, Michocki Lindsay B, Alonso-Mori Roberto, Britz Alexander, Deb Aniruddha, DePonte Daniel P, Glownia James M, Kaneshiro April K, Kieninger Christoph, Koralek Jake, Meadows Joseph H, van Driel Tim B, Kräutler Bernhard, Kubarych Kevin J, Penner-Hahn James E, Sension Roseanne J
机构信息
Department of Chemistry , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109-1055 , United States.
Linac Coherent Light Source , SLAC National Accelerator Laboratory , 2575 Sand Hill Road , Menlo Park , California 94025 , United States.
出版信息
J Phys Chem Lett. 2019 Sep 19;10(18):5484-5489. doi: 10.1021/acs.jpclett.9b02202. Epub 2019 Sep 4.
Polarized transient X-ray absorption near-edge structure (XANES) was used to probe the excited-state structure of a photostable B antivitamin (Coβ-2-(2,4-difluorophenyl)-ethynylcobalamin, FPhEtyCbl). A drop-on-demand delivery system synchronized to the LCLS X-ray free electron laser pulses was implemented and used to measure the XANES difference spectrum 12 ps following excitation, exposing only ∼45 μL of sample. Unlike cyanocobalamin (CNCbl), where the Co-C bond expands 15-20%, the excited state of FPhEtyCbl is characterized by little change in the Co-C bond, suggesting that the acetylide linkage raises the barrier for expansion of the Co-C bond. In contrast, the lower axial Co-N bond is elongated in the excited state of FPhEtyCbl by ca. 10% or more, comparable to the 10% elongation observed for Co-N in CNCbl.
极化瞬态X射线吸收近边结构（XANES）被用于探测一种光稳定的B族抗维生素（Coβ-2-(2,4-二氟苯基)-乙炔基钴胺素，FPhEtyCbl）的激发态结构。一种与直线加速器相干光源（LCLS）X射线自由电子激光脉冲同步的按需滴加递送系统被实现并用于测量激发后12皮秒的XANES差谱，仅暴露约45微升样品。与钴胺素（CNCbl）不同，在CNCbl中Co-C键扩展15 - 20%，而FPhEtyCbl的激发态的特征是Co-C键变化很小，这表明乙炔基连接提高了Co-C键扩展的势垒。相比之下，在FPhEtyCbl的激发态中，较低的轴向Co-N键伸长了约10%或更多，这与在CNCbl中观察到的Co-N键10%的伸长相当。
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