Tuning the Magnetic Interactions and Relaxation Dynamics of Dy2 Single-Molecule Magnets.
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.
State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (P.R. China).
Shufang
S
Xue
School of Science, Xi'an Jiaotong University, Xi'an, 710049 (P.R. China).
Yun-Nan
YN
Guo
Theory of Nanomaterials Group and INPAC Institute for Nanoscale Physics and Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan, 200F, 3001 (Belgium).
Liviu
L
Ungur
State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (P.R. China). tang@ciac.ac.cn.
Jinkui
J
Tang
Theory of Nanomaterials Group and INPAC Institute for Nanoscale Physics and Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan, 200F, 3001 (Belgium).
Liviu F
LF
Chibotaru
N,O ligands; ab initio calculations; dysprosium; magnetic properties; single-molecule magnets