Employing Schiff-base macrocycles to probe the effect of ligand field on the relaxation dynamics of a family of DyIII SMMs

Three macrocyclic complexes DyCl3(N5)·4H2O (4), DyCl3(N3O2)·6H2O (5) and DyCl3(db-N3O3)·6H2O (6) (where db = dibenzo) have been prepared in which the DyIII ion is equatorially bound by the Schiff-base macrocycles conferring a pseudo-D5h geometry on complexes 4 and 5 that is supported by TGA, molar conductance measurements, as well as Raman and far-IR spectroscopy. In contrast the coordination geometry of 6 is less clear with analytical data supporting 7-, 8- or 9-coordination depending on whether the L3 macrocycle chelates in a tetra-, penta- or hexa-dentate manner. For all three complexes, ac susceptibility data reveal slow relaxation of the magnetisation in zero field below 15 K with a distribution of relaxation rates.

Graphical abstractThree macrocyclic complexes DyCl3(N5)·4H2O (4), DyCl3(N3O2)·6H2O (5) and DyCl3(db-N3O3)·6H2O (6) have been prepared in which the DyIII ion is bound in the equatorial plane by the Schiff-base macrocycles. Ac magnetic susceptibility measurements reveal that all three complexes display slow relaxation of magnetisation consistent with SMM behaviour.Figure optionsDownload full-size imageDownload as PowerPoint slide