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Abstract：
Two-dimensional metal-organic frameworks (2D-MOFs) represent a category of atomically thin materials that combine the structural tunability of molecular systems with the crystalline structure characteristic of solids. The strong bonding between the organic linkers and transition metal centers is expected to result in delocalized electronic states. However, it remains largely unknown how the band structure in 2D-MOFs emerges through the coupling of electronic states in the building blocks. Here, we demonstrate the on-surface synthesis of a 2D-MOF exhibiting prominent π-conjugation. Through a combined experimental and theoretical approach, we provide direct evidence of band structure formation upon hierarchical self-assembly, going from metal-organic complexes to a conjugated two-dimensional framework. Additionally, we identify the robustly dispersive nature of the emerging hybrid states, irrespective of the metallic support type, highlighting the tunability of the band structure through charge transfer from the substrate. Our findings encourage the exploration of band-structure engineering in 2D-MOFs for potential applications in electronics and photonics.
摘要：
二维金属有机骨架（2D-MOF）代表一类原子级薄材料，将分子系统的结构可调性与固体的晶体结构特征相结合。有机接头和过渡金属中心之间的强键合会导致离域电子态。然而,目前还不清楚2D-MOFs中的能带结构是如何通过构建块中电子态的耦合而出现的。这里,我们展示了表现出突出的π-共轭的2D-MOF的表面合成。通过实验和理论相结合的方法，我们提供了分层自组装时能带结构形成的直接证据，从金属-有机络合物到共轭二维框架。此外,我们确定了新兴混合态的强大分散性，无论金属支撑类型如何，通过从衬底转移电荷来突出能带结构的可调性。我们的发现鼓励探索2D-MOF中的能带结构工程，以用于电子和光子学的潜在应用。
