Interplay between anisotropy and magnetic exchange to modulate the magnetic relaxation behaviours of phenoxo bridged Dy2 dimers with axial β-diketonate co-ligands

A series of Schiff base LH ((E)-2-((pyridin-2-ylmethylene)amino)phenol) supported phenoxo bridged symmetric [Dy-2(L)(2)(hfac)(4)] (1), [Dy-2(L)(2)(tfac)(4)] (2) and asymmetric [Dy-2(L)(2)(thd)(3)(NO3)]center dot 1.5H(2)O (3) binuclear complexes were isolated using differently substituted beta-diketonate co-Eigands (Hhfac = hexafluoroacety-Eacetonate, Htfac = trifluoroacetylacetonate, and Hthd = 2,2,6,6-tetramethyl-3,5-heptanedione). In all the three complexes 1-3, the two LH Eigands provide phenoxo bridging and N-donor atoms. The {Dy-2(mu(2)-O)(2)} magnetic core structures with LH Eigands are found to be the same in 1-3 while the dissimilar functionahties of the axially coordinated different beta-diketonate co-Eigands Way a crucial role in modulating the magnetic anisotropy of individual Dy-III sites and magnetic exchange between them. The experimental static magnetic behaviour suggests the presence of intramolecular antiferromagnetic interactions in all the three complexes 1-3. The strength of the magnetic exchange coupling decreases with increasing magnetic anisotropy of individual Dy-III ions from complex 1 to complex 3 and simultaneously their zero-field slow magnetic relaxation behaviors were found to increase with effective energy barriers (Delta E/k(B)) of 9.04 K, 24.06 K and 25.65 K, respectively. Furthermore, the DFT and ab initio theoretical calculations performed on the X-ray structures of complexes 1-3 support our experimental findings.

Automated summary

A series of dysprosium complexes were synthesized using differently substituted β-diketonate co-ligands. The magnetic behaviors of these complexes were found to be influenced by the co-ligands. Experimental results showed the presence of intramolecular antiferromagnetic interactions in all the complexes, and increasing magnetic anisotropy led to a decrease in magnetic exchange coupling and an increase in zero-field slow magnetic relaxation behavior.