The role of exchange interaction between Cu(ii) and Ln(iii) ions in SMM behaviour and magnetocaloric effects has been extensively investigated by both experimental and theoretical CASSCF/RASSI-SO/SINGLE_ANISO methods.

No abstract

The strategic design and synthesis of two isomeric Cu II complexes, [CuL A ] and [CuL B ], of asymmetrically dicondensed N 2 O 3 -donor Schiff-base ligands (where H 2 L A and H 2 L B are N-salicylidene-N′-3-methoxysalicylidenepropane-1,2-diamine and N-3-methoxysalicylidene-N′-salicylidenepropane-1,2-diamine, respectively) have been accomplished via a convenient Cu II template method. These two complexes have been used as metalloligands for the synthesis of three pairs of Cu−Ln isomeric complexes [CuL(μ-NO 3 )Ln(NO 3 ) 2 (H 2 O)]• CH 3 CN (for complexes 1A−3A, L = L A , and for complexes 1B−3B, L = L B and Ln = Gd, Tb, and Dy, respectively), all of which have been characterized structurally. In all six isomorphous and isostructural complexes, the decacoordinated Ln III centers and pentacoordinated Cu II centers possess sphenocorona and square-pyramidal geometries, respectively. The isomeric pair of Cu−Gd compounds shows field-induced slow relaxation of magnetization, although they present the typical isotropic behavior of Gd III complexes, indicating that slow relaxation is not due to the usual energy barrier originating from the magnetic anisotropy. The isostructural derivatives with the ion-anisotropic lanthanides Tb III and Dy III do not show slow magnetic relaxation with or without a direct-current bias field, demonstrating that the magnetic response of the isotropic system Cu II −Gd III occurs through different mechanisms than the rest of the Ln cations.

The causes behind the fluctuations from a linear dependence of the electrochemical signal of a guest bound metalloligand [CuL] with the Lewis acidity of redox-inactive cations were established by using UV-vis spectroscopy and cyclic voltammetry.

Four heterometallic dinuclear CuIILnIII (Ln = Tb and Dy) complexes derived from two different N2O3 donor unsymmetrical Schiff base ligands exhibit SMM behaviour.