Six-Coordinate Lanthanide Complexes: Slow Relaxation of Magnetization in the Dysprosium(III) Complex

A series of six-coordinate lanthanide complexes {(H3O)[Ln(NA)(2)]H2O}(n) (H(2)NA=5-hydroxynicotinic acid; Ln=Gd-III (1Gd); Tb-III (2Tb); Dy-III (3Dy); Ho-III (4Ho)) have been synthesized from aqueous solution and fully characterized. Slow relaxation of the magnetization was observed in 3Dy. To suppress the quantum tunneling of the magnetization, 3Dy diluted by diamagnetic Y-III ions was also synthesized and magnetically studied. Interesting butterfly-like hysteresis loops and an enhanced energy barrier for the slow relaxation of magnetization were observed in diluted 3Dy. The energy barrier () and pre-exponential factor ((0)) of the diluted 3Dy are 75K and 4.21x10(-5)s, respectively. This work illustrates a successful way to obtain low-coordination-number lanthanide complexes by a framework approach to show single-ion-magnet-like behavior.