Xiaoyan Zou

Exploiting single-molecule magnets of β-diketone dysprosium complexes with C3v symmetry: suppression of quantum tunneling of magnetization

A series of four β-diketone mononuclear dysprosium complexes, namely, Dy(EIFD)3(H2O)·CH2Cl2 (1), Dy(EIFD)3(DMF)·CH2Cl2 (2), Dy(EIFD)3(DMSO) (3), and Dy(EIFD)3(TPPO) (4) (EIFD: 1-(1-ethyl-1H-indol-3-yl)-4,4,4-trifluorobutane-1,3-dione, TPPO: triphenylphosphine oxide), have been isolated by the reactions of a newly designed β-diketone EIFD, DyCl3·6H2O and DMF, DMSO, TPPO, respectively. X-ray crystallographic analysis reveals that complexes 1–4 are isomorphic mononuclear structures in which the Dy(III) ion is rarely seven-coordinated with C3v geometry. Magnetic studies indicate that all complexes 1–4 are single-molecule magnets. The correlations between magnetism and the distortion of the coordination symmetry around the Dy(III) ions have been investigated. Notably, the quantum tunneling of magnetization (QTM), which universally exists in the lanthanide complexes, has been effectively suppressed in this system more related to the less deviation from the ideal C3v symmetry.

Azacyclo-auxiliary ligand-tuned SMMs of dibenzoylmethane Dy(III) complexes

A series of four β-diketone mononuclear dysprosium complexes, namely, Dy(DBM)3(bpy) (1), Dy(DBM)3(phen)·Tol (2), Dy(DBM)3(dpq)·Tol (3), and Dy(DBM)3(dppz) (4) (bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, dpq = dipyrazine[2,3-f:2′,3′-h]quinoxaline, dppz = dipyrido[3,2-a:2′,3′-c]phenazine, Tol = toluene) have been isolated by the reactions of dibenzoylmethane (DBM), azacyclo-auxiliary ligands and DyCl3·6H2O. X-ray crystallographic analysis reveals that complexes 1–4 are all eight-coordinate mononuclear structures. The azacyclo-auxiliary ligands have a dramatic effect on the structure and magnetic characteristics of complexes 1–4, originating from the different degrees of deviation from the ideal coordination symmetries. Complexes 1 and 2 display a single relaxation mode under 0 Oe and complexes 3 and 4 display two single relaxation modes under 2000 Oe.

Magnetic dynamics of two salen type Dy2 complexes modulated by coordination geometry

Two salen type dinuclear dysprosium complexes, namely [Dy(H2L) (NO3)3]2·CH2Cl2·CH3OH·H2O (1) and [Dy(H2L1)2(NO3)3]2·2CH2Cl2·2CH3OH (2) [H2L = N,N′-(1,3-propylene)bis(3-methoxysalicylideneimine) and H2L1 = N,N′-(1,3-propylene)bis(salicylideneimine)], were isolated from the reactions of Dy(NO3)3·6H2O with two different but similar salen type ligands (H2L and H2L1), respectively. X-ray crystallographic analyses revealed that two crystallographically equivalent Dy(III) ions for 1 and two crystallographically non-equivalent Dy(III) ions for 2 were both bridged by two ligands displaying broken hula hoop-like and hula hoop-like coordination geometries for complexes 1 and 2, respectively, which resulted in the distinct magnetic properties that complex 2 exhibited with relatively higher energy barriers under a 2 kOe dc field.

CCDC 872859: Experimental Crystal Structure Determination

Related Article: Xiaoyan Zou, Pengfei Yan, Juwen Zhang, Fengming Zhang, Guangfeng Hou, Guangming Li|2013|Dalton Trans.|42|13190|doi:10.1039/C3DT51556G