Chirality Control of "Asymmetric Oxygen Atom" generated by Metal Ion Coordination

在本项目中，我们将通过对配体的精心设计和金属离子的选择，阐明金属配位氧原子产生手性的可能性及其局限性，提出“不对称氧”的全新概念。通过适当的配体设计，我们将完全基于“不对称氧”分离和表征对映体。同时，我们将对化合物的物理性质进行分析，以寻找“不对称氧”的可能应用。首先，我们考察了使非手性氧原子与金属中心配位的可能因素。在此基础上，我们构建了络合物中不对称氧和不对称氮同时生成的体系，发现不对称氮的构型控制着不对称氧的构型。此外，我们还成功地利用配体在不同位置上的不对称碳原子生成了不对称氧原子。铜配合物的x射线晶体学表明，不对称氧的构型控制着不对称氧原子的构型。手性配合物在铜原子的d-d过渡区表现出特有的棉花效应。这表明不对称氧的构型在溶液状态下保持不变。

In this project, by careful design of the ligand and the selection of metal ion, we are going to clarify the possibility of the chirality generated on the metal-coordinated oxygen atom and its limitation, proposing the brand-new concept of "Asymmetric Oxygen". By appropriate design of the ligand, we are going to isolate and characterize the enantiomer based on exclusively "Asymmetric Oxygen". At the same time, we are going to analyze the physical properties of the compound in order to find possible application of "Asymmetric Oxygen".At first, we examined the possible factors that are necessary to coordinate the achiral oxygen atom to the metal center. On the basis of this study, we constructed the system in which asymmetric oxygen and asymmetric nitrogen are generated simultaneously in the complex, and found that the configuration of the asymmetric nitrogen controls the configuration of the asymmetric oxygen. Furthermore, we succeeded in generating asymmetric oxygen atom using a ligand with an asymmetric carbon atom in various positions. X-ray crystallography of copper complexes revealed that the configuration of asymmetric oxygen controls the configuration of asymmetric oxygen atom. The chiral complexes exhibited characteristic Cotton effect in the d-d transition region of copper atom. This indicates that the configuration of asymmetric oxygen is preserved in solution state.