The emergence of electrically conductive metal-organic frameworks (MOFs) has led to applications in chemical sensing and electrical energy storage, among others. The most conductive MOFs are made from organic ligands and square-planar transition metal ions connected into two-dimensional (2D) sheets stacked on top of each other. Their electrical properties are thought to depend critically on the covalency of the metal-ligand bond, and less importance is given to out-of-plane charge transport. Here, we report a series of lanthanide-based MOFs that allow fine tuning of the sheet stacking. In these materials, the Ln3+ ions lie between the planes of the ligands, thus connecting organic layers into a 3D framework through lanthanide-oxygen chains. Here, efficient charge transport is found to occur primarily perpendicular to the 2D sheets. These results demonstrate that high conductivity in layered MOFs does not necessarily require a metal-ligand bond with highly covalent character, and that interactions between organic ligands alone can produce efficient charge transport pathways.

中文翻译：

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层状镧系金属有机框架中高效且可调节的一维电荷传输。


导电金属有机框架（MOF）的出现导致其在化学传感和电能存储等领域的应用。导电性最强的 MOF 由有机配体和方形平面过渡金属离子制成，它们连接成彼此堆叠的二维 (2D) 片。人们认为它们的电性能主要取决于金属-配体键的共价键，而面外电荷传输则不太重要。在这里，我们报告了一系列基于镧系元素的 MOF，可以对片材堆叠进行微调。在这些材料中，Ln3+离子位于配体平面之间，从而通过镧系元素氧链将有机层连接成3D框架。在这里，发现有效的电荷传输主要发生在垂直于二维片材的方向上。这些结果表明，层状 MOF 中的高电导率不一定需要具有高度共价特性的金属-配体键，并且仅有机配体之间的相互作用就可以产生有效的电荷传输途径。