Gee Leland B, Lim Jinkyu, Kroll Thomas, Sokaras Dimosthenis, Alonso-Mori Roberto, Lee Chien-Ming
LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
SSRL, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
J Am Chem Soc. 2023 Sep 27;145(38):20733-20738. doi: 10.1021/jacs.3c04479. Epub 2023 Aug 23.
Photolytic delivery of nitric oxide and nitroxide has substantial biomedical and phototherapeutic applications. Here, we utilized hard X-ray spectroscopic methods to identify key geometric and electronic structural features of two photolabile {FeNO} complexes where the compounds differ in the presence of a pendant thiol in [Fe(NO)(PS2)(PS2H)] and thioether in [Fe(NO)(PS2)(PS2CH)] with the former complex being the only transition metal system to photolytically generate HNO. Fe Kβ XES identifies the photoreactant systems as essentially Fe(II)-NO, while valence-to-core XES extracts a NO oxidation state of +0.5. Finally, the pre-edge of the Fe high-energy-resolution fluorescence detected (HERFD) XAS spectra is shown to be acutely sensitive to perturbation of the Fe-NO covalency enhanced by the 3d-4p orbital mixing dipole intensity contribution. Collectively, this X-ray spectroscopic approach enables future time-resolved insights in these systems and extensions to other challenging redox noninnocent {FeNO} systems.
一氧化氮和氮氧化物的光解递送具有重要的生物医学和光治疗应用。在此，我们利用硬X射线光谱方法来确定两种光不稳定的{FeNO}配合物的关键几何和电子结构特征，其中化合物在[Fe(NO)(PS2)(PS2H)]中存在侧链硫醇和在[Fe(NO)(PS2)(PS2CH)]中存在硫醚而有所不同，前一种配合物是唯一能光解产生HNO的过渡金属体系。Fe Kβ XES将光反应物体系确定为本质上的Fe(II)-NO，而价到芯XES提取出+0.5的NO氧化态。最后，Fe高能分辨率荧光检测（HERFD）XAS光谱的前缘显示对由3d-4p轨道混合偶极强度贡献增强的Fe-NO共价性的扰动非常敏感。总体而言，这种X射线光谱方法能够在未来对这些体系进行时间分辨研究，并扩展到其他具有挑战性的氧化还原非无辜{FeNO}体系。
