金属有机框架 (MOF) 中的缺陷可以显着改变它们的孔结构和化学性质。然而，表征缺陷的分子结构一直是一个巨大的挑战，特别是当缺陷在晶格中不规则分布时。在这项工作中，我们应用了基于固态核磁共振 (NMR) 的表征策略来评估缺陷的化学性质。该策略利用了对配位敏感的磷探针分子，例如三甲基膦（TMP）和三甲基氧化膦（TMPO），可以区分缺陷酸度的细微差异。已经在有缺陷的理想 MOF 晶格中发现了多种局部化学环境。缺陷的几何尺寸也可以通过使用不同大小的探针分子的同系物来评估。此外，我们的方法提供了一种可靠的方法来量化缺陷位点的密度，并结合局部孔隙环境的分子细节。全面的固态 NMR 策略对于更好地理解 MOF 结构和指导设计具有所需催化或吸附性能的 MOF 具有重要价值。

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The defects in metal-organic frameworks (MOFs) can dramatically alter their pore structure and chemical properties. However, it has been a great challenge to characterize the molecular structure of defects, especially when the defects are distributed irregularly in the lattice. In this work, we applied a characterization strategy based on solid-state nuclear magnetic resonance (NMR) to assess the chemistry of defects. This strategy takes advantage of the coordination-sensitive phosphorus probe molecules, e.g., trimethylphosphine (TMP) and trimethylphosphine oxide (TMPO), that can distinguish the subtle differences in the acidity of defects. A variety of local chemical environments have been identified in defective and ideal MOF lattices. The geometric dimension of defects can also be evaluated by using the homologs of probe molecules with different sizes. In addition, our method provides a reliable way to quantify the density of defect sites, which comes together with the molecular details of local pore environments. The comprehensive solid-state NMR strategy can be of great value for a better understanding of MOF structures and for guiding the design of MOFs with desired catalytic or adsorption properties.