硫茴香醚
化学
金属有机骨架
催化作用
位阻效应
活动站点
合理设计
配体(生物化学)
钼
组合化学
光化学
立体化学
有机化学
纳米技术
生物化学
材料科学
受体
吸附
作者
Seryeong Lee,Haomiao Xie,Zhihengyu Chen,Mohammad Rasel Mian,Alejandra Gómez‐Torres,Zoha H. Syed,Susanne Reischauer,Karena W. Chapman,Massimiliano Delferro,Omar K. Farha
摘要
The local environment of a metal active site plays an important role in affecting the catalytic activity and selectivity. In recent studies, tailoring the behavior of a molybdenum-based active site via modulation of the first coordination sphere has led to improved thioanisole oxidation performance, but disentangling electronic effects from steric influences that arise from these modifications is nontrivial, especially in heterogeneous systems. To this end, the tunability of metal–organic frameworks (MOFs) makes them promising scaffolds for controlling the coordination sphere of a heterogeneous, catalytically active metal site while offering additional attractive features such as crystallinity and high porosity. Herein, we report a variety of MOF-supported Mo species, which were investigated for catalytic thioanisole oxidation to methyl phenyl sulfoxide and/or methyl phenyl sulfone using tert-butyl hydroperoxide (tBHP) as the oxidant. In particular, MOFs of contrasting node architectures were targeted, presenting a unique opportunity to investigate the stereoelectronic control of Mo active sites in a systematic manner. A Zr6-based MOF, NU-1000, was employed along with its sulfated analogue Zr6-based NU-1000-SO4 to anchor a dioxomolybdenum species, which enabled examination of support-mediated active site polarizability on catalytic performance. In addition, a MOF containing a mixed metal node, Mo-MFU-4l, was used to probe the stereoelectronic impact of an N-donor ligand environment on the catalytic activity of the transmetalated Mo center. Characterization techniques, including single crystal X-ray diffraction, were concomitantly used with reaction time course profiles to better comprehend the dynamics of different Mo active sites, thus correlating structural change with activity.
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