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

A series of four new Dy₁₂ dodecanuclear clusters based on azobenzene derivative ligands of salicylic acid (L1-L4) has been synthesized and characterized in the crystalline phase using X-ray diffraction on single crystal and powder, IR spectroscopy, elemental analysis, and DSC-TGA methods. It was revealed that all obtained clusters exhibit the formation of the similar metallic cluster nodes, as vertex-sharing heterocubanes, obtained from four Dy³⁺ cations, three bridging hydroxyl groups, and O atoms from the salicylic ligands. The coordination geometry around the Dy(III) centers has been carefully analyzed. Whereas Dy and Dy with L1 and L2 containing Me and OMe groups in para positions of the phenyl rings, respectively, form similar porous 3D diamond-like molecular networks due to CH-π interactions, for Dy with L3 bearing NO₂-electron-withdrawing group, the generation of 2D molecular grids assembled by π-π staking is observed, and for Dy with L4 bearing phenyl substituent, 3D hexagonal channels have been generated. The complexes Dy, Dy, and Dy exhibit a zero-field slow magnetic relaxation effect. After UV irradiation of Dy, a decrease of the magnetic anisotropy energy barrier displaying the possibility of control over magnetic properties by the external stimulus has been observed.