Katoh Keiichi, Yasuda Nobuhiro, Damjanović Marko, Wernsdorfer Wolfgang, Breedlove Brian K, Yamashita Masahiro
Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan.
Diffraction and Scattering Division, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5198, Japan.
Chemistry. 2020 Apr 9;26(21):4805-4815. doi: 10.1002/chem.201905400. Epub 2020 Mar 25.
A supramolecular complex (1⋅C ) was prepared by assembling (C60-Ih)[5,6]fullerene (C ) with the dinuclear Tb triple-decker complex [(TPP)Tb(Pc)Tb(TPP)] (1: Tb =trivalent terbium ion, Pc =phthalocyaninato, TPP =tetraphenylporphyrinato) with quasi-D symmetry to investigate the relationship between the coordination symmetry and single-molecule magnet (SMM) properties. Tb -Pc triple-decker complexes (Tb Pc ) have an important advantage over Tb -Pc double-decker complexes (TbPc ) since the magnetic relaxation processes correspond to the Zeeman splitting when there are two 4f spin systems. The two Tb sites of 1 are equivalent, and the twist angle (φ) was determined to be 3.62°. On the other hand, the two Tb sites of 1⋅C are not equivalent. The φ values for sites Tb1 and Tb2 were determined to be 3.67° and 33.8°, respectively, due to a change in the coordination symmetry of 1 upon association with C . At 1.8 K, 1 and 1⋅C undergo different magnetic relaxations, and the changes in the ground state affect the spin dynamics. Although 1 and 1⋅C relax via QTM in a zero applied magnetic field (H), H dependencies of the magnetic relaxation times (τ) for H>1500 Oe are similar. On the other hand, for H<1500 Oe, the τ values have different behaviors since the off-diagonal terms ( ) affect the magnetic relaxation mechanism. From temperature (T) and H dependences of τ, spin-phonon interactions along with direct and Raman mechanisms explain the spin dynamics. We believe that a supramolecular method can be used to control the magnetic anisotropy along the C rotation axis and the spin dynamic properties in dinuclear Ln -Pc multiple-decker complexes.
通过将(C60-Ih)[5,6]富勒烯(C)与具有准D对称性的双核Tb三层配合物[(TPP)Tb(Pc)Tb(TPP)] (1: Tb =三价铽离子，Pc =酞菁，TPP =四苯基卟啉)组装，制备了一种超分子配合物(1⋅C)，以研究配位对称性与单分子磁体(SMM)性质之间的关系。与Tb -Pc双层配合物(TbPc)相比，Tb -Pc三层配合物(Tb Pc)具有一个重要优势，因为当存在两个4f自旋系统时，磁弛豫过程对应于塞曼分裂。1的两个Tb位点是等效的，扭转角(φ)被确定为3.62°。另一方面，1⋅C的两个Tb位点不等效。由于1与C缔合时配位对称性发生变化，Tb1和Tb2位点的φ值分别被确定为3.67°和33.8°。在1.8 K时，1和1⋅C经历不同的磁弛豫，基态的变化影响自旋动力学。尽管1和1⋅C在零外加磁场(H)中通过量子隧穿磁矩(QTM)弛豫，但对于H>1500 Oe，磁弛豫时间(τ)的H依赖性是相似的。另一方面，对于H<1500 Oe，τ值具有不同的行为，因为非对角项( )影响磁弛豫机制。从τ的温度(T)和H依赖性来看，自旋-声子相互作用以及直接和拉曼机制解释了自旋动力学。我们认为，超分子方法可用于控制双核Ln -Pc多层配合物中沿C旋转轴的磁各向异性和自旋动力学性质。
