Nakakoji Takashi, Yoshino Kaori, Izutsu Kazuki, Sato Hirofumi, Miyake Hiroyuki, Mieda Eiko, Shinoda Satoshi, Tsukube Hiroshi, Kawasaki Hideya, Arakawa Ryuichi, Ono Daisuke, Shizuma Motohiro
Department of Chemistry, Graduate School of Science, Osaka City University, Osaka, Japan.
Osaka Research Institute of Industrial Science and Technology, Osaka, Japan.
Front Chem. 2020 Nov 30;8:598598. doi: 10.3389/fchem.2020.598598. eCollection 2020.
A series of copper(II) complexes with chiral tetradentate ligands, '-ethylene- bis(-amino acid methyl amide or methyl ester) prepared from alanine, phenylalanine, valine or proline, was generated in methanol. The copper complexes provided three component complexes in the presence of a free chiral amino acid. The enantioselectivity for the amino acid was evaluated by electrospray ionization-mass spectrometry coupled with the deuterium-labeled enantiomer method and these copper complexes were found to exhibit high enantioselectivity for free amino acids having bulky side chains. This result suggests that steric interaction between the tetradentate ligand and free amino acid was a major factor in chiral recognition. The copper complex with a chiral tetradentate ligand prepared from -proline showed opposite enantioselectivity to copper complexes consisting of tetradentate ligands prepared from other -amino acids. The conformational difference of the tetradentate ligand in the copper complex was found to be significant for enantioselectivity.
一系列由丙氨酸、苯丙氨酸、缬氨酸或脯氨酸制备的带有手性四齿配体“-乙烯-双（-氨基酸甲酰胺或甲酯）”的铜（II）配合物在甲醇中生成。在游离手性氨基酸存在的情况下，这些铜配合物形成了三元配合物。通过电喷雾电离质谱联用氘标记对映体方法评估了对氨基酸的对映选择性，发现这些铜配合物对具有庞大侧链的游离氨基酸表现出高对映选择性。该结果表明四齿配体与游离氨基酸之间的空间相互作用是手性识别的主要因素。由-脯氨酸制备的带有手性四齿配体的铜配合物表现出与由其他-氨基酸制备的四齿配体组成的铜配合物相反的对映选择性。发现铜配合物中四齿配体的构象差异对映选择性具有重要意义。
