Detailed magnetic properties and theoretical calculation in ferromagnetic coupling DyIII-MII 3d-4f complexes based on a 1,4,7,10‑tetraazacyclododecane derivative.

The magnetic properties of five DyIII-MII 3d-4f complexes (M = Mn, Fe, Co, Ni and Zn) were studied in detail by comparison due to the same molecule construction. The DyIII-MII assemble (M = Mn, Fe and Ni) behave as field-induced SMMs resulting from the ferromagnetic coupling between DyIII and MII ions, while DyIII-ZnII is SIM and DyIII-CoII does not show the magnetic relaxation. [Display omitted] • In this paper, A series of DyIII-MII 3d-4f complexes (M = Mn, Fe, Co, Ni and Zn) were synthesized. • Their magnetic properties were compared by the magnetostructural correlation. • The coupling between DyIII and MII ions (M = Mn, Fe and Ni) is ferromagnetic. Four Dy-based 3d-4f complexes [MIIDyIII(H 2 L)(NO 3) 3 ](CH 3 OH) 2 (H 4 L = N , N' , N'' , N''' -tetra(2-hydroxy-3-methoxy-5-methylbenzyl)-1,4,7,10-tetraazacyclododecane, M = Mn (2), Fe (3), Co (4) and Ni (5), the solvent of compound 5 is uncertain) were synthesized through the reference method of complex [ZnIILnIII(H 2 L)(NO 3) 3 ](CH 3 OH) 2 (1). The magnetic properties of all the five complexes were measured for comparison. The magnetic results show that all the complexes except 4 behave as single-molecule magnets (SMMs). The magnetostructural analysis and theoretical calculation indicate the ferromagnetic coupling in 2 , 3 and 5 as well as the antiferromagnetic coupling in 4 between DyIII and transition metal ions, while the SMM properties of 1 are caused by the anisotropy of single DyIII ions only. Unexpectedly, neither of the magnetic anisotropic ions in one molecule, namely DyIII and CoII, provides greater advantages for SMM performance. This investigation experimentally proves that the coexistence of magnetic anisotropy of lanthanide ions and ferromagnetic coupling between lanthanide and transition metal ions is important for the design of 3d-4f SMMs. [ABSTRACT FROM AUTHOR]