ИСТИНА

Molecular magnetism is a peculiar feature that distinguishes sandwich lanthanide complexes with phthalocyanines from other coordination compounds with tetrapyrrole ligands. Fine tuning of the magnetic properties of these complexes involves static control by modification of the coordinating ligands and dynamic control by supramolecular interactions [1,2]. In the present work, we discuss the influence of supramolecular interactions on the magnetic properties of novel heteroleptic trisphthalocyaninates containing butoxy- and crown-substituted ligands – [(BuO)8Pc]M[(BuO)8Pc]M*[(15C5)4Pc], where M and M* are Tb and/or Y. We found that the conformational state of the complexes can be switched by changing the solvation environment – in aromatic solvents both ligand pairs are in staggered conformations, providing the metal centres with a square antiprismatic environment characterised by relatively low axial magnetic anisotropies, ax. Changing the solvent to halogenated alkanes causes the "[(BuO)8Pc]M[(BuO)8Pc]" fragment to switch from staggered to gauche, significantly increasing the anisotropy of the metal centre. On the other hand, the presence of crown-ether units allows the application of cation-induced supramolecular assembly to form six-deck dimers with collinear metal centres, which exhibit efficient through-space f-f interactions causing a spectacular decrease in the magnetisation relaxation rate.