Liu Mei-Jiao, Wu Shu-Qi, Li Jia-Xin, Zhang Yi-Quan, Sato Osamu, Kou Hui-Zhong
Department of Chemistry , Tsinghua University , Beijing 100084 , P.R. China.
Institute for Materials Chemistry and Engineering and IRCCS , Kyushu University , 744 Motooka , Nishi-ku, Fukuoka 819-0395 , Japan.
Inorg Chem. 2020 Feb 17;59(4):2308-2315. doi: 10.1021/acs.inorgchem.9b03105. Epub 2020 Jan 27.
Two rhodamine 6G-based mononuclear dysprosium complexes, Dy(L)(L)·EtO·1.5MeOH·0.5HO () and Dy(L)(HO)(MeCN)·2HO·MeCN () (L = salicylaldehyde rhodamine 6G hydrazone, L = 2-pyridylcarboxaldehyde benzoyl hydrazone), are synthesized, aiming at improving the magnetic behavior by modulating their coordination environment. Both complexes own one exclusive short Dy-O coordination bond as the predominant bond and exhibit single-molecule magnet behavior under zero dc field with the energy barrier (/) of 90 K () and 320 K () and apparent hysteresis at 1.9 K. The calculations indicate that the short Dy-O bond determines the direction of magnetic anisotropic axis for and . The quantum tunneling of magnetization (QTM) between the ground Kramers doublets (KDs) in cannot be neglected, leading to an experimental / much lower than the calculated energy of the first excited state (318.2 K). For , the stronger magnetic anisotropy and negligible QTM between the ground KDs guarantees that the energy barrier is close to the calculated energy of first KDs (320.8 K). On the other hand, the presence of ring-opened xanthene moiety makes complexes and in the solid state emit red light with emission bands of 645 and 658 nm, respectively.
合成了两种基于罗丹明6G的单核镝配合物，Dy(L)(L)·EtO·1.5MeOH·0.5HO () 和 Dy(L)(HO)(MeCN)·2HO·MeCN ()（L = 水杨醛罗丹明6G腙，L = 2 - 吡啶甲醛苯甲酰腙），旨在通过调节其配位环境来改善磁行为。两种配合物都有一个独特的短Dy - O配位键作为主要键，并在零直流场下表现出单分子磁体行为，其能垒（/）分别为90 K () 和320 K ()，在1.9 K时具有明显的磁滞现象。计算表明，短Dy - O键决定了 和 的磁各向异性轴方向。 中基态克莱默斯双态（KDs）之间的磁化量子隧穿（QTM）不可忽略，导致实验测得的 / 远低于第一激发态的计算能量（318.2 K）。对于 ，更强的磁各向异性以及基态KDs之间可忽略的QTM保证了能垒接近第一KDs的计算能量（320.8 K）。另一方面，开环呫吨部分的存在使得配合物 和 在固态下分别发射出波长为645和658 nm的红色光。
