Investigation on the Magnetic Relaxation Mechanism and the Magnetic Coupling for a Coiii2coiidy Single Molecule Magnet☆

Abstract

A novel [CoIICoIII2Dy(HL)(H2L)(H3L)(hmp)3(NO3)](NO3)∙3CH3OH∙H2O (1, H4L = 2-(((2-hydroxy-3-methoxyphenyl)methylene)amino)-2-(hydroxymethyl)-1,3-propanediol, Hhmp = 2-pyridinemethanol) complex and its diluted complex (2) were successfully obtained. One CoII, one CoIII, one DyIII and four O atoms in 1 formed a cubane missing one vertice, which was further linked with another CoIII by two O atoms from hmp- or HL3- ligand. 1 and 2 both exhibit field-induced single molecule magnet properties, with the effective energy barriers of 85.94 K and 58.03 K, respectively. Together with the theoretical calculations, this study indicated that intramolecular magnetic interactions within 1 can suppress QTM and can enhance SMM performance of 1. Moreover, the critical angle of 109.59° for the CoII…GdIII pair transformed from ferromagnetic coupling to antiferromagnetic coupling was first determined by DFT calculations.

Keywords: Single molecule magnets, Co-Dy heterometallic complexes, Magnetic couplings, Theoretical studies, Critical angle