Takada Kenji, Kambe Tetsuya, Kinoshita Taira, Kuzume Akiyoshi, Imaoka Takane, Yamamoto Kimihisa
JST-ERATO, Tokyo Institute of Technology, 4259 Nagatsutacho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan.
Research Institute for Science & Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
Langmuir. 2025 Jul 22;41(28):18788-18796. doi: 10.1021/acs.langmuir.5c02104. Epub 2025 Jul 12.
The use of dendrimers for metal cluster synthesis is an attractive approach for alloying multiple metal atoms into metal clusters because of the nanosized spaces and wide variety of metal salts that can be coordinated by dendrimers. However, the repeating structure of the dendrimers is generally not suitable for the precise assembly of different kinds of metal salts in them. Here, an amine/imine hybrid dendrimer was synthesized as a template for bimetallic assembly via the partial reduction of dendritic polyphenylazomethines (DPAs), which exhibit atomically precise metal salt assembly via 1:1 coordination between metal ions and their imine sites. The partial reduction of 12-imine DPA gave an 8-amine-4-imine hybrid dendrimer. The difference in the reactivity of the amine and imine sites enabled selective and sequential coordination to different metal salts. At first, Ir(III) was selectively coordinated to imine sites via the cyclometalation reaction. X-ray analysis demonstrated the selective assembly of Ir(III) at the imine sites. Then, Fe(III) or Ga(III) complexes were formed at the remaining amine sites. The stepwise metal ion assembly was also confirmed by theoretical calculations based on density functional theory. Therefore, our amine/imine hybrid dendrimer can form multinuclear metal complexes with atomic precision.
由于树枝状大分子具有纳米级空间以及能与多种金属盐配位，因此将树枝状大分子用于金属簇合成是一种将多种金属原子合金化到金属簇中的有吸引力的方法。然而，树枝状大分子的重复结构通常不适合在其中精确组装不同种类的金属盐。在此，通过对树枝状聚苯基偶氮甲碱（DPA）进行部分还原，合成了一种胺/亚胺杂化树枝状大分子作为双金属组装的模板，该树枝状聚苯基偶氮甲碱通过金属离子与其亚胺位点之间的1:1配位实现原子精确的金属盐组装。对12-亚胺DPA进行部分还原得到了一种8-胺-4-亚胺杂化树枝状大分子。胺和亚胺位点反应性的差异使得能够选择性地、顺序地与不同的金属盐配位。首先，通过环金属化反应使Ir(III)选择性地与亚胺位点配位。X射线分析表明Ir(III)在亚胺位点处实现了选择性组装。然后，在剩余的胺位点形成Fe(III)或Ga(III)配合物。基于密度泛函理论的理论计算也证实了逐步的金属离子组装。因此，我们的胺/亚胺杂化树枝状大分子能够以原子精度形成多核金属配合物。
