Xing-Cai Huang

A single-molecule magnet based on heptacyanomolybdate with the highest energy barrier for a cyanide compound.

Three trinuclear Mn2Mo molecules based on the orbitally degenerate [Mo(CN)7](4-) anion were prepared, one of which is the first single-molecule magnet (SMM) based on heptacyanomolybdate. The blocking temperature and the energy barrier (U = 40.5 cm(-1)) are records for a cyanide-based SMM. Wide hysteresis loops and sharp quantum tunneling steps were observed from single-crystal measurements.

Cation-Dependent Magnetic Ordering and Room-Temperature Bistability in Azido-Bridged Perovskite-Type Compounds

A series of end-to-end azido-bridged perovskite-type compounds [(CH3)nNH4-n][Mn(N3)3] (n = 1-4) were synthesized and characterized. Structural phase transitions indicating the general lattice flexibility were observed and confirmed by the crystal structures of different phases. These materials show cation-dependent magnetic ordering at up to 92 K and magnetic bistability near room temperature.

Field-Induced Slow Magnetic Relaxation in Cobalt(II) Compounds with Pentagonal Bipyramid Geometry

Field-induced slow magnetic relaxation was observed for air-stable mononuclear cobalt(II) compounds with pentagonal bipyramid geometry. These are the first examples of such behavior observed in the seven-coordinated mononuclear 3d metal compounds.

End-on azido-bridged 3d-4f complexes showing single-molecule-magnet property.

Four tetranuclear 3d-4f complexes with the 4f centers bridged solely by end-on azide bridges were reported. The [CuTb]2 compound displays single-molecule-magnet behavior with hysteresis loops observed at up to 2.4 K.

Rhodamine-based field-induced single molecule magnets in Yb(III) and Dy(III) series

The reaction between the rhodamine-6G-2-(hydrozinomethyl) quinolin-8-ol (HQR1) ligand and Ln(tta)3·2H2O precursors (tta = 2-thenoyltrifluoroacetone) leads to the formation of a series of mononuclear complexes with formula [Ln(QR1)(tta)2]·(CH3OH)x(H2O)y (3–6) for (Ln = Yb, x = 1, y = 0 for 3; Ln = Dy, x = 1, y = 0.5 for 4; Ln = Tb, x = 2, y = 0 for 5; Ln = Ho, x = 2, y = 0 for 6) together with [Dy(QR1)2][NO3]·(CH3OH)(H2O) (2) and the reported [Yb(QR1)2][NO3]·(CH3OH)(H2O)0.5 (1), for the purpose of magnetic comparison. Their X-ray structures revealed that the coordination environment of each Ln(III) center is filled by two tta carboxylate groups and a tetrachelate N2O2 binding site coming from the deprotonated HQR1 ligand. The Yb and Dy complexes showed the field-induced slow relaxation of magnetization. Both Yb(III)-containing compounds were characterized by X-band EPR and magnetism studies, which revealed the different effective g values and slow paramagnetic relaxation. Comparison between two Yb(III) complexes 1 and 3 shows that the magnetoanisotropy and the barrier height of the magnetic relaxation are sensitive to the subtle change in the coordination environment of the central metal ion. However, in Dy3+ series, QTM is difficult to overcome even under the dc field and the subtle variation of the coordination environment leads to a tiny change in the energy barrier of slow magnetization relaxation. These results show that ligand-donating ability while maintaining molecular symmetry can be controlled to design single molecule magnets with enhanced relaxation barriers.