Tuning Crystal Packing and Magnetic Properties in a Series of [Dy12] Metallocubanes Based on Azobenzene Derivatives of Salicylic Acid

A series of four new Dy-12 dodecanuclearclustersbased on azobenzene derivative ligands of salicylic acid have beensynthesized and characterized from a structural point of view. Threeof these clusters display a single molecular magnetic behavior; theirshort lifetimes have been measured; and for one compound, preliminarilydata concerning the irradiation of the solid-state powder have beenreported. A series of four new Dy-12 dodecanuclear clusters basedon azobenzene derivative ligands of salicylic acid (L1-L4) has been synthesized and characterized inthe crystalline phase using X-ray diffraction on single crystal andpowder, IR spectroscopy, elemental analysis, and DSC-TGA methods.It was revealed that all obtained clusters exhibit the formation ofthe similar metallic cluster nodes, as vertex-sharing heterocubanes,obtained from four Dy3+ cations, three bridging hydroxylgroups, and O atoms from the salicylic ligands. The coordination geometryaround the Dy(III) centers has been carefully analyzed. Whereas Dy-12-L1 and Dy-12-L2 with L1 and L2 containing Me and OMe groups in para positions of the phenyl rings, respectively, form similarporous 3D diamond-like molecular networks due to CH-& pi;interactions, for Dy-12-L3 with L3 bearing NO2-electron-withdrawing group, the generationof 2D molecular grids assembled by & pi;-& pi; stakingis observed, and for Dy-12-L4 with L4 bearing phenyl substituent, 3D hexagonal channels have been generated.The complexes Dy-12-L1, Dy-12-L2, and Dy-12-L3 exhibit a zero-fieldslow magnetic relaxation effect. After UV irradiation of Dy-12-L1, a decrease of the magnetic anisotropy energybarrier displaying the possibility of control over magnetic propertiesby the external stimulus has been observed.

Automated summary

A series of four new Dy-12 dodecanuclear clusters based on azobenzene derivative ligands of salicylic acid have been synthesized and characterized. The formation of similar metallic cluster nodes in all obtained clusters has been revealed. Different porous 3D molecular networks and grids have been observed in different compounds. Three of the clusters exhibit a slow magnetic relaxation effect and one compound shows a decrease in the magnetic anisotropy energy barrier after UV irradiation, indicating the potential control over magnetic properties by external stimulus.