A Chiral Cyclometalated Iridium Star of David [2]Catenane
A Chiral Cyclometalated Iridium Star of David [2]Catenane
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DOI：
10.1021/jacs.0c12038
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发表时间：
2021-01-05
影响因子：
15
通讯作者：
Vitorica-Yrezabal, Inigo J.
中科院分区：
文献类型：
--
作者：
August, David P.;Jaramillo-Garcia, Javier;Vitorica-Yrezabal, Inigo J.
尽管圆形螺旋可以与一系列不稳定的过渡金属中心组装，但仅以“金属手性”为例（即，没有手性配体的体系）和异金属（即，混合金属体系、外消旋或手性）环状螺旋化合物都尚未被探索。在这里，我们报告的对映选择性合成的异金属（Ir 2 Zn 4）六聚体环状螺旋和其阐述成相应的三重联锁星星的大卫[2]索烃。Ir（III）的相对惰性使得能够使用手性金属构建块对映体特异性合成六聚环状螺旋酸酯。得到的大卫[2]链烷的星星是手性6-2-1键，形成为单一拓扑对映异构体。（Ir 2 Zn 4）-索烃的X射线晶体结构显示两个95原子长的大环中的每一个包围在六个金属八面体金属离子周围并且彼此包围，形成三重互锁的圆形双螺旋。两个PF 6-阴离子存在于中心腔的上方和下方。大卫[2]链烷的星星，无论有或没有配位的Zn（II）离子，都保留了环化Ir（III）配合物的物理化学性质。合成策略开辟了新的研究方向和机会，为其他手性结，链接，和异金属圆形螺旋组装。
Although circular helicates can be assembled with a range of labile transition-metal centers, solely "chiral-at-metal" examples (i.e., systems without chiral ligands) and heterometallic (i.e., mixed metal systems, racemic or chiral) circular helicates both remain unexplored. Here, we report on the enantioselective synthesis of a heterometallic (Ir2Zn4) hexameric circular helicate and its elaboration into the corresponding triply interlocked Star of David [2]catenane. The relative inertness of Ir(III) enables enantiospecific synthesis of the hexameric circular helicate using chiral-at-metal building blocks. The resulting Star of David [2]catenane, which is a chiral 6-2-1 link, is formed as a single topological enantiomer. The X-ray crystal structure of the (Ir2Zn4)-catenane shows each of the two 95-atom-long macrocycles entwined around the six metal octahedral metal ions and each other, forming a triply interlocked circular double helix. Two PF6- anions reside above and below the central cavity. The Star of David [2]catenane, both with and without coordinated Zn(II) ions, retains the photophysical properties characteristic of cyclometalated Ir(III) complexes. The synthetic strategy opens up new research directions and opportunities for the assembly of other chiral knots, links, and heterometallic circular helicates.