Efficient Long-Range Stereochemical Communication and Cooperative Effects in Self-Assembled Fe4L6 Cages

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• 作者：Naoki Ousaka ; Sergio Grunder ; Ana M. Castilla ; Adam C. Whalley ; J. Fraser Stoddart ; Jonathan R. Nitschke
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：September 19, 2012
• 年：2012
• 卷：134
• 期：37
• 页码：15528-15537
• 全文大小：631K
• 年卷期：v.134,no.37(September 19, 2012)
• ISSN：1520-5126

文摘

A series of large, optically active Fe₄L₆ cages was prepared from linear 5,5鈥?bis(2-formylpyridines) incorporating varying numbers (n = 0鈥?) of oligo-p-xylene spacers, chiral amines, and Fe^II. When a cage was constructed from the ligand bridged by one p-xylene spacer (n = 1) and a bulky chiral amine, both a homochiral Fe₂L₃ helicate and Fe₄L₆ cage were observed to coexist in solution due to a delicate balance between steric factors. In contrast, when a less bulky chiral amine was used, only the Fe₄L₆ cage was observed. In the case of larger cages (n = 2, 3), long-range (>2 nm) stereochemical coupling between metal centers was observed, which was minimally diminished as the ligands were lengthened. This communication was mediated by the ligands鈥?geometries and rigidity, as opposed to gearing effects between xylene methyl groups: the metal-centered stereochemistry was not observed to affect the axial stereochemistry of the ligands.