Tuning the Magnetic Interactions and Relaxation Dynamics of Dy2 Single-Molecule Magnets

• Published in: Chemistry : a European journal Vol. 21; no. 40; pp. 14099 - 14106
• Main Authors: Xue, Shufang, Guo, Yun-Nan, Ungur, Liviu, Tang, Jinkui, Chibotaru, Liviu F.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 28-09-2015; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: ab initio calculations; Acetic acid; Antiferromagnetism; Chemistry; Covalent bonds; Dysprosium; Hydrazine; Hydrazines; Magnetic induction; magnetic properties; Magnets; N,O ligands; O ligands; Quantum tunnelling; single-molecule magnets; Thermal energy; dysprosium; ab initio calculations; magnetic properties; single-molecule magnets; N,O ligands
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201501866

Efficient modulation of single‐molecule magnet (SMM) behavior was realized by deliberate structural modification of the Dy2 cores of [Dy2(a′povh)2(OAc)2(DMF)2] (1) and [Zn2Dy2(a′povh)2(OAc)6]⋅4 H2O (2; H2a′povh=N′‐[amino(pyrimidin‐2‐yl)methylene]‐o‐vanilloyl hydrazine). Compound 1 having fourfold linkage between the two dysprosium ions shows high‐performance SMM behavior with a thermal energy barrier of 322.1 K, whereas only slow relaxation is observed for compound 2 with only twofold connection between the dysprosium ions. This remarkable discrepancy is mainly because of strong axiality in 1 due to one pronounced covalent bond, as revealed by experimental and theoretical investigations. The significant antiferromagnetic interaction derived from bis(μ2‐O) and two acetate bridging groups was found to be crucial in leading to a nonmagnetic ground state in 1, by suppressing zero‐field quantum tunneling of magnetization.
Magnetostructural correlations: Single‐molecule magnet (SMM) behavior was modulated by deliberate structural modification of the Dy2 cores of [Dy2(a′povh)2(OAc)2(DMF)2] (1) and [Zn2Dy2(a′povh)2(OAc)6]⋅4 H2O (2; H2a′povh=N′‐[amino(pyrimidin‐2‐yl)methylene]‐o‐vanilloyl hydrazine; see figure). Compound 1 shows high‐performance SMM behavior, whereas only slow relaxation is observed for 2.