Self-assembly of fish-bone and grid-like Co^II-based single-molecule magnets using dihydrazone ligands with NNN and NNO pockets

Abstract

Three CoII complexes, [Co2(H2L1)2](ClO4)4·4CH3OH (1), [Co2(H4L2)2](ClO4)4 (2) and [Co4(H4L2)4](ClO4)8 (3), were constructed by self-assembly of symmetrical dihydrazone ligands H2L1 and H4L2 with CoII ions under different synthetic conditions. Fish-bone like...

Role of molecular symmetry in the magnetic relaxation dynamics of five-coordinate Dy(iii) complexes

“…The slopes of 0.96(8) and 6.48(3) for 2 suggest that the magnetic relaxation goes through QTM and Raman processes. 40,41 It is necessary to add that, at the lowest temperature of a few Kelvin, the dominant relaxation mechanism is usually QTM (quantum tunnelling of the magnetisation), which is governed by environmental factors, such as the presence of nuclear spins and dipolar coupling. QTM between magnetic ground states is naturally temperature-independent, hence the relaxation rate is often well described by τ QTM −1 = B 1 /(1 + B 2 H 2 ), 42 where B 1 and B 2 are the empirical parameters and H represents the applied dc field.…”

Hierarchical subcomponent self-assembly of covalent triple-stranded complexes with 3d–4f vertices: luminescence and magnetic properties

“…Such a disparity should be attributed to the significant orbital contribution of the high-spin octahedral Co II ions. [57][58][59] The χ M T products remain nearly constant up to 100 K, below which they decrease slowly and reach the minimum value of 27.66 cm 3 K mol −1 at 2 K. The decreases below 100 K are likely to be caused by the depopulation of the Stark levels of Dy III and the spin-orbital effect of Co II . Moreover, the possible weak antiferromagnetic interactions between Dy III and Co II may also make some contributions to the decreases of χ M T below 100 K, as observed in other heterometallic Co II -Dy III compounds.…”

The Assembly of Grid-type Lanthanide Cluster

“…[62,63] This kind of relaxation can usually be suppressed by the application of dc field. [64,65] The optimized dc field was determined through the field-dependent ac susceptibility measurements (Figure S15), giving the optimized dc field of 500 Oe. After applying this dc field, frequency-and temperature-dependent χ" peaks were observed in the ac measurements (Figures 3 and S16), indicative of the field-induced single-molecule magnetic property.…”