Mapping metal sequences in MOFs Most metal-organic frameworks (MOFs) contain just one type of metal in the nodes connecting the organic linkers. Multivariate MOFs containing multiple metals can offer greater selectivity in sorption and catalytic properties, but determining the arrangement of metals in these materials is challenging. Ji et al. found that atom-probe tomography can reveal sequences of metals for MOF-74 single crystals containing combinations of cobalt, cadmium, lead, and manganese ions. In this MOF, the metals form oxide rods that are connected by the organic linker into a honeycomb lattice. The obtained sequences, which were tuned by varying the proportion of metals and synthesis temperature, could be random, short and long duplicates, and single metal insertions. Science, this issue p. 674 Atom-probe tomography revealed the metal sequences in the oxide rods in a multivariate metal-organic framework compound. We mapped the metal sequences within crystals of metal-oxide rods in multivariate metal-organic framework–74 containing mixed combinations of cobalt (Co), cadmium (Cd), lead (Pb), and manganese (Mn). Atom probe tomography of these crystals revealed the presence of heterogeneous spatial sequences of metal ions that we describe, depending on the metal and synthesis temperature used, as random (Co, Cd, 120°C), short duplicates (Co, Cd, 85°C), long duplicates (Co, Pb, 85°C), and insertions (Co, Mn, 85°C). Three crystals were examined for each sequence type, and the molar fraction of Co among all 12 samples was observed to vary from 0.4 to 0.9, without changing the sequence type. Compared with metal oxides, metal-organic frameworks have high tolerance for coexistence of different metal sizes in their rods and therefore assume various metal sequences.

中文翻译：

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多元金属有机骨架中金属的测序

在 MOF 中映射金属序列 大多数金属有机框架 (MOF) 在连接有机接头的节点中仅包含一种金属。包含多种金属的多元 MOF 可以在吸附和催化性能方面提供更大的选择性，但确定这些材料中金属的排列具有挑战性。姬等人。发现原子探针断层扫描可以揭示含有钴、镉、铅和锰离子组合的 MOF-74 单晶的金属序列。在这种 MOF 中，金属形成氧化物棒，通过有机连接体连接成蜂窝状晶格。通过改变金属的比例和合成温度来调整获得的序列，可以是随机的、短的和长的重复以及单个金属插入。科学，这个问题 p。674 原子探针断层扫描揭示了多元金属有机骨架化合物中氧化物棒中的金属序列。我们在包含钴 (Co)、镉 (Cd)、铅 (Pb) 和锰 (Mn) 的混合组合的多元金属有机骨架中绘制了金属氧化物棒晶体内的金属序列 – 74。这些晶体的原子探针断层扫描揭示了我们描述的金属离子的异质空间序列的存在，这取决于所使用的金属和合成温度，作为随机 (Co, Cd, 120°C)，短重复 (Co, Cd, 85° C)、长重复（Co、Pb、85°C）和插入（Co、Mn、85°C）。对于每种序列类型检查了三个晶体，观察到所有 12 个样品中 Co 的摩尔分数从 0.4 到 0.9 不等，序列类型没有改变。与金属氧化物相比，