New mononuclear Dy(<scp>iii</scp>) complex based on a calix[4]arene ligand with two appended salicylideneamine groups decorated with azophenyl fragments: synthesis, crystalline assembly and slow magnetic relaxation behavior

Metal-organic single-molecule magnets (SMMs), especially single-ion magnets (SIMs), attract growing attention due to their unique magnetic behavior, which can be used for the development of computing technologies. Herein, we report the synthesis of a new mononuclear Dy(III) complex (2-Dy) using a calix[4]arene ligand (2), decorated with two lower rim-appended salicylideneamine groups, bearing azophenyl moieties. The structures of both the ligand and Dy(III) complex were thoroughly characterized in the crystalline phase. X-ray diffraction of ligand 2 revealed the formation of a racemic mixture of left-handed and right-handed conformers. Upon binding to the Dy(III) atom, the macrocycle 2 behaves as a highly coordinating ligand by totally capping the metal coordination sphere, leading to the formation of a distorted triangular dodecahedron coordination sphere (<i>D</i>_2d symmetry). In the crystalline phase, for 2-Dy, two complex enantiomer counterparts were stacked into 1D homochiral chains due to weak CH/π interactions. Analysis of magnetic properties showed that the obtained complex exhibited slow magnetic relaxation behavior at a temperature up to 10 K in the absence of an external dc field.