Jakub Zdeněk, Shahsavar Azin, Planer Jakub, Hrůza Dominik, Herich Ondrej, Procházka Pavel, Čechal Jan
CEITEC-Central European Institute of Technology, Brno University of Technology, Purkyňova 123, Brno 61200, Czech Republic.
Institute of Physical Engineering, Faculty of Mechanical Engineering, Brno University of Technology, Technická 2896/2, Brno 61200,Czech Republic.
J Am Chem Soc. 2024 Feb 7;146(5):3471-3482. doi: 10.1021/jacs.3c13212. Epub 2024 Jan 22.
The functionality of 2D metal-organic frameworks (MOFs) is crucially dependent on the local environment of the embedded metal atoms. These atomic-scale details are best ascertained on MOFs supported on well-defined surfaces, but the interaction with the support often changes the MOF properties. We elucidate the extent of this effect by comparing the Fe-TCNQ 2D MOF on two weakly interacting supports: graphene and Au(111). We show that the Fe-TCNQ on graphene is nonplanar with iron in quasi-tetrahedral sites, but on Au(111) it is planarized by stronger van der Waals interaction. The differences in physical and electronic structures result in distinct properties of the supported 2D MOFs. The d center position is shifted by 1.4 eV between Fe sites on the two supports, and dramatic differences in chemical reactivity are experimentally identified using a TCNQ probe molecule. These results outline the limitations of common on-surface approaches using metal supports and show that the intrinsic MOF properties can be partially retained on graphene.
二维金属有机框架（MOF）的功能关键取决于嵌入金属原子的局部环境。这些原子尺度的细节最好在明确界定的表面上所支撑的MOF上确定，但与支撑体的相互作用往往会改变MOF的性质。我们通过比较在两种弱相互作用支撑体上的Fe-TCNQ二维MOF来阐明这种效应的程度：石墨烯和Au(111)。我们表明，石墨烯上的Fe-TCNQ是非平面的，铁处于准四面体位置，但在Au(111)上，它通过更强的范德华相互作用而被平面化。物理和电子结构的差异导致了所支撑的二维MOF具有不同的性质。两种支撑体上的Fe位点之间，d中心位置偏移了1.4 eV，并且使用TCNQ探针分子通过实验确定了化学反应性的显著差异。这些结果概述了使用金属支撑体的常见表面方法的局限性，并表明MOF的固有性质在石墨烯上可以部分保留。
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