Kong Ming, Feng Xin, Wang Jia, Zhang Yi-Quan, Song You
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People's Republic of China.
Jiangsu Key Lab For NSLSCS, School of Physical Science and Technology, Nanjing Normal University, Nanjing 210023, People's Republic of China.
Dalton Trans. 2021 Jan 14;50(2):568-577. doi: 10.1039/d0dt03854g. Epub 2020 Dec 23.
Four Dy complexes, [Dy(NO)(L)(HO)]·2MeCN (1), [Dy(NO)(L)(HO)]·2(NO)·DMBD·2MeOH (2), [Dy(NO)(L)(TPO)]·2MeCN (3) and [Dy(L')(HO)]·4MeCN (4), were elaborately synthesized, structurally characterized and magnetically investigated (HL = 2,6-dimethoxyphenol, HL' = 4-hydroxy-3,5-dimethoxybenzaldehyde, DMBD = 1,1'-dimethyl-[4,4'-bipyridine]-1,1'-diium and TPO = phosphine triphenyl oxide). In 1-3, the nearly planar molecular structures consisting of two Dy ions and two L ligands are almost perpendicular to four nitrate ligands, which provides an opportunity to introduce auxiliary ligands (HO or TPO) at the terminal position along the DyDy orientation of [Dy]. The slightly discrepant coordination environment around the Dy ion with different terminal ligands plays a key role in tuning the magnetic anisotropy, and further strongly affects the magnetic properties of 1-4. The magnetic studies reveal that they all behave as single-molecule magnets (SMMs) at zero dc field with ferromagnetic dipole-dipole interaction between Dy ions. The dynamic magnetic investigations give the energy barriers of 107.5 (1), 127.1 (2), 168.7 (3) and 251.9 K (4), respectively. The magnetic axis orientation of the ground state gradually verges on the Dy-O bond from 1 to 4, leading to the stronger uniaxial anisotropy of Dy ions and better SMM properties of 3 and 4. In addition, complexes 3 and 4 possess higher energy barriers than reported dinuclear Dy-SMMs also constructed from HL or HL' with β-diketone. It is believed that the ligands coordinating to the Dy ion at both terminals of the DyDy linkage improve the SMM properties of dinuclear Dy complexes. This design may provide a new strategy for obtaining dinuclear Dy-based SMMs.
精心合成了四种镝配合物，即[Dy(NO)(L)(H₂O)]·2MeCN (1)、[Dy(NO)(L)(H₂O)]·2(NO₃)·DMBD·2MeOH (2)、[Dy(NO)(L)(TPO)]·2MeCN (3) 和 [Dy(L')(H₂O)]·4MeCN (4)，对其进行了结构表征和磁性研究（HL = 2,6 - 二甲氧基苯酚，HL' = 4 - 羟基 - 3,5 - 二甲氧基苯甲醛，DMBD = 1,1'-二甲基 - [4,4'-联吡啶]-1,1'-二鎓，TPO = 三苯基氧化膦）。在1 - 3中，由两个镝离子和两个L配体组成的近乎平面的分子结构几乎垂直于四个硝酸根配体，这为沿着[Dy]的Dy - Dy方向在末端位置引入辅助配体（H₂O或TPO）提供了机会。镝离子周围带有不同末端配体的配位环境略有差异，这在调节磁各向异性方面起着关键作用，并进一步强烈影响1 - 4的磁性。磁性研究表明，它们在零直流场下均表现为单分子磁体（SMMs），镝离子之间存在铁磁偶极 - 偶极相互作用。动态磁性研究分别给出了107.5 (1)、127.1 (2)、168.7 (3) 和251.9 K (4) 的能垒。基态的磁轴方向从1到4逐渐趋向于Dy - O键，导致镝离子的单轴各向异性增强，3和4的SMM性质更好。此外，配合物3和4具有比报道的同样由HL或HL'与β - 二酮构建的双核Dy - SMMs更高的能垒。据信，在Dy - Dy键两端与镝离子配位的配体改善了双核镝配合物的SMM性质。这种设计可能为获得基于双核镝的SMMs提供一种新策略。
