ic7b00625_si_001.pdf (3.4 MB)
Single-Molecule Magnet Behavior Enhanced by Synergic Effect of Single-Ion Anisotropy and Magnetic Interactions
journal contribution
posted on 2017-06-30, 13:04 authored by Li Zhang, Yi-Quan Zhang, Peng Zhang, Lang Zhao, Mei Guo, Jinkui TangAs the simplest entity carrying intramolecular
magnetic interactions, a dinuclear lanthanide complex serves as a
model to investigate the effects of magnetic interactions on relaxation
of magnetization, and importantly, it proves to be an efficient method
to obtain robust single-molecule magnets via improving the communication
between lanthanide centers. Here, three Dy2 complexes (1, 2, 3) with a similar structural
motif, namely, [Dy2(HL)2(NO3)2(CH3CN)2]·2CH3CN (1), [Dy2(HL)2(NO3)2(DMF)2]·2H2O (2), and Dy2(HL)2(NO3)2(DMF)4 (3), were successfully assembled. One critical difference found
in this series of complexes is that the Dy center in complex 3 is coordinated by one more solvent molecule. Surprisingly,
complex 3 exhibits the best magnet-like behavior, as
evidenced by the high effective barrier and butterfly-type hysteresis,
although the crystal field effect around Dy ions is weakened heavily. Ab initio calculations revealed the crucial reason is the
significant synergic effect between single-ion anisotropy and magnetic
interactions, i.e., not only the axiality of the Dy ion is improved
efficiently but also the exchange magnetic interactions increased
to the same order of magnitude to the dipolar interaction in 3. This effect mainly benefits from the elaborate modification
of the local coordinate environment around the Dy ion, which results
in a special arrangement of anisotropy axes different from the other
two complexes. It demonstrates that the magnetic interactions could
be effectively enhanced by means of deliberate local structural modulation.