Regulating Magnetic Relaxations of Cyano-Bridged {DyIIIMoV} Systems by Tuning the N-Sites in β-Diketone Ligands

Cyano-bridged 4d-4f molecular nanomagnets have re-called increasing research interests in molecular magnetism since they offer more possibilities in achieving novel nanomagnets with versatile structures and magnetic interactions. In this work, four beta-diketone ligands bearing different substitution N-sites were designed and synthesized, namely 1-(2-pyridyl)-3-(3-pyridyl)-1,3-propanedione (HL1), 1,3-Bis (3-pyridyl)-1,3-propanedione (HL2), 1-(4-pyridyl)-3-(3-pyridyl)-1,3-propanedione (HL3), and 1,3-Bis (4-pyridyl)-1,3-propanedione (HL4), to tune the magnetic relaxation behaviors of cyano-bridged {(DyMoV)-Mo-III} systems. By reacting with DyCl3 center dot 6H(2)O and K4Mo(CN)(8)center dot 2H(2)O, four cyano-bridged complexes, namely {[Dy[Mo-V(CN)(8)](HL1)(2)(H2O)(3)]}center dot 6H(2)O (1), {[Dy[Mo-V(CN)(8)](HL3)(H2O)(3)(CH3OH)]}(2)center dot 2CH(3)OH center dot 3H(2)O (2), {[Dy[Mo-V(CN)(8)](HL3)(H2O)(2)(CH3OH)]center dot H2O} n (3), and {[Dy[Mo-V-(CN)(8)](HL4)(2)(H2O)(3)]}center dot 2H(2)O center dot CH3OH (4) were obtained. Structural analyses revealed that 1 and 4 are binuclear complexes, 2 has a tetragonal structure, and 3 exhibits a stair-like polymer chain structure. The Dy-III ions in all complexes have eightcoordinated configurations with the coordination spheres DyO7N1 for 1 and 4, DyO6N2 for 2, and DyO5N3 for 3. Magnetic measurements indicate that 1 is a zero-field single-molecule magnet (SMM) and complexes 2-4 are field-induced SMMs, with complex 4 featuring a two-step relaxation process. The magnetic characterizations and ab initio calculations revealed that changing the N-sites in the beta-diketone ligands can effectively alter the structures and magnetic properties of cyano-bridged 4d-4f nanomagnets by adjusting the coordination environments of the Dy-III centers.

Automated summary

In this study, four β-diketone ligands with different substitution N-sites were designed and synthesized, and four cyano-bridged complexes were obtained. Structural analysis revealed that 1 and 4 are binuclear complexes, 2 has a tetragonal structure, and 3 exhibits a stair-like polymer chain structure. Magnetic measurements showed that 1 is a zero-field single-molecule magnet (SMM) and 2-4 are field-induced SMMs.