Physik-Department E20, Technische Universität München, D-85748 Garching, Germany.
IMDEA Nanoscience, 28049 Madrid, Spain.
Nat Chem. 2016 Jul;8(7):657-62. doi: 10.1038/nchem.2507. Epub 2016 May 16.
The recognition of quasicrystals, which exhibit long-range order but lack translational symmetry, represented both the introduction of a new class of materials and a transformative breakthrough in crystallography. Concomitant with the exploration of quasicrystallinity, metal-organic architectures emerged as promising and versatile systems with significant application potential. Their building principles have been studied extensively and become manifest in a multitude of intricate amorphous and crystalline phases. To date, however, indications for quasicrystalline order have been elusive in metal-organic coordination networks (MOCNs). Here we employ rare-earth-directed assembly to construct a two-dimensional tiling with quasicrystalline characteristics at a well-defined gold substrate. By careful stoichiometry control over europium centres and functional linkers, we produced a porous network, including the simultaneous expression of four-fold, five-fold and six-fold vertices. The pertaining features were directly inspected by scanning tunnelling microscopy, and the molecule-europium reticulation was recognized as square-triangle tessellation with dodecagonal symmetry. Our findings introduce quasicrystallinity in surface-confined MOCNs with a nanoporous structure and anticipate functionalities that arise from quasicrystalline ordering of the coordinative spheres.
准晶的发现，即具有长程有序但缺乏平移对称性的物质，既代表了一类新材料的引入，也是晶体学的一个变革性突破。随着对准晶的探索，金属有机架构作为具有重要应用潜力的有前途和多功能系统出现了。它们的构建原则已经得到了广泛的研究，并在许多复杂的无定形和晶体相中得到了体现。然而，迄今为止，在金属有机配位网络（MOCN）中，准晶序的迹象仍然难以捉摸。在这里，我们采用稀土导向组装，在明确的金基底上构建具有准晶特征的二维平铺。通过对铕中心和功能链接器进行仔细的化学计量控制，我们生成了一个多孔网络，包括同时表达四、五和六重顶点。这些特征通过扫描隧道显微镜直接进行了检查，并且发现分子-铕的交织结构具有十二角对称的正方形-三角形平铺。我们的发现将具有纳米多孔结构的表面受限 MOCN 中的准晶引入，并预测了源于配位球准晶排序的功能。
