Macrocycle supported dinuclear lanthanide complexes with different β-diketonate co-ligands displaying zero field single-molecule magnetic behaviour

Three different sets of isomorphous dinuclear Gd/Dy complexes, [Ln 2 (L′)(acac) 4 ]·2H 2 O·2CH 3 CN (Ln = Gd ( 1 Gd ) and Dy ( 2 Dy ); acac = acetylacetonate), [Ln 2 (L′)(tfac) 4 ] (Ln = Gd ( 3 Gd ) and Dy ( 4 Dy ); tfac = trifluoroacetylacetonate), and [Ln 2 (L′)(hfac) 4 ] (Ln = Gd ( 5 Gd ) and Dy ( 6 Dy ); hfac = hexafluoroacetylacetonate), where H 2 L′ is a new Ln-assisted in situ generated macrocyclic ligand from acyclic Schiff base HL, derived from a condensation reaction of 2,6-diformyl-4-methylphenol and N , N -dimethyldipropylenetriamine, have been synthesized by the reaction of lanthanide nitrates with ligand HL in the presence of different β-diketonate co-ligands. Structural analysis revealed that the lanthanide ions in these complexes are all eight-coordinated in a square antiprismatic geometry with D 4d symmetry. Magnetic measurements of these complexes revealed that the magnetic interaction between Gd 3+ ions is antiferromagnetic, while Dy 3+ ions are ferromagnetically coupled in dimetallic complexes, and the detailed analysis of Gd analogues discloses the significant influence of the different β-diketonate co-ligands on the magnitude of the magnetic interactions. All three Dy complexes exhibit zero field single-molecule magnet behaviour with energy barriers varying in the close range 60.1-62.8 K. The orientation of the magnetic axes and crystal structural parameters were critically analysed to establish magneto-structural correlations in three Dy-based SMMs to gain an in depth understanding of the magnetic dynamics in these systems. Three different sets of isomorphous dinuclear Gd/Dy complexes with an uncommon macrocyclic ligand and β-diketonate co-ligands were reported in which Dy 2 analogues are zero field SMMs.