Metal organic polyhedra (MOPs) such as coordination cages and clusters are increasingly utilized across many fields, but their geometrically selective assembly during synthesis is nontrivial. When ligand coordination along these polyhedral edges is arranged in an unsymmetrical mode or the bridging ligand itself is nonsymmetric, a vast combinatorial space of potential isomers exists complicating formation and isolation. Here we describe two generalizable combinatorial methodologies to explore the geometrical space and enumerate the configurational isomers of MOPs with discrimination of the chiral and achiral structures. The methodology has been applied to the case of the octahedron {Bi₆Fe₁₃L₁₂} which has unsymmetrical coordination of a carboxylate ligand (L) along its edges. For these polyhedra, the enumeration methodology revealed 186 distinct isomers, including 74 chiral pairs and 38 achiral. To explore the programming of these, we then used a range of ligands to synthesize several configurational isomers. Our analysis demonstrates that ligand halo-substituents influence isomer symmetry and suggests that more symmetric halo-substituted ligands counterintuitively yield lower symmetry isomers. We performed mass spectrometry studies of these {Bi₆Fe₁₃L₁₂} clusters to evaluate their stability and aggregation behavior in solution and the gas phase showing that various isomers have different levels of aggregation in solution.

中文翻译：

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探索金属-氧簇的金属-有机多面体 (MOP) 的几何空间

金属有机多面体 (MOP)，例如配位笼和簇，越来越多地用于许多领域，但它们在合成过程中的几何选择性组装并不简单。当沿着这些多面体边缘的配体配位以不对称模式排列或桥接配体本身不对称时，存在潜在异构体的巨大组合空间，使形成和分离复杂化。在这里，我们描述了两种通用的组合方法来探索几何空间并枚举 MOP 的构型异构体，并区分手性和非手性结构。该方法已应用于八面体 {Bi ₆ Fe ₁₃ L ₁₂} 沿其边缘具有羧酸盐配体（L）的不对称配位。对于这些多面体，枚举方法揭示了 186 个不同的异构体，包括 74 个手性对和 38 个非手性。为了探索这些的编程，我们随后使用了一系列配体来合成几种构型异构体。我们的分析表明配体卤素取代基会影响异构体对称性，并表明更对称的卤素取代配体违反直觉会产生较低对称性的异构体。我们对这些 {Bi ₆ Fe ₁₃ L ₁₂ } 簇进行了质谱研究，以评估它们在溶液和气相中的稳定性和聚集行为，表明各种异构体在溶液中具有不同的聚集水平。