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采用重稀土离子(Dy、Ho、Er、Tm、Yb)研究了水溶液中L-精氨酸的构象。结果表明,距稀土配位中心4个或4个键以上的配体核的接触位移都很小,在稀土离子附近的配体核具有显著的接触位移。通过对配体磁性核结构因子的实验值进行模拟,建立了水溶液中L-精氨酸的整体构象。在L-精氨酸稀土配合物中,配体的羧基与稀土离子配位,配体的骨架结构位于稀土离子的零偶极位移锥面的外侧。对于羧基的双齿配位模式,计算得到的RE~(3+)-O键长为0.21nm。在溶液中配体以伸展状态存在,分子骨架呈全反式构象。
The heavy rare earth ions (Dy, Ho, Er, Tm, Yb) were used to study the conformation of L-arginine in aqueous solution. The results show that the contact nuclei of ligand nuclei with more than four or more bonds from the coordination centers of rare earths are very small, and the ligand nuclei near the rare earth ions have significant contact displacement. The overall conformation of L-arginine in aqueous solution was established by simulating the experimental values of the magnetic core structure factor of the ligand. In the L-arginine rare earth complex, the carboxyl group of the ligand is coordinated with the rare earth ions, and the framework structure of the ligand is located outside the zero dipole displacement conical surface of the rare earth ions. For bidentate coordination mode of carboxyl, the calculated RE ~ (3 +) - O bond length is 0.21nm. In solution, the ligand exists in an extended state and the molecular framework is in an all-trans conformation.