Mannich Base Ligands as Versatile Platforms for SMMs

Abstract

Aminophenol Mannich base derivatives are versatile and flexible ligands for preparing a wide variety of homo- and heterometallic discrete coordination compounds, ranging from mononuclear to hexanuclear, which exhibit aesthetically pleasant structures with intricate topologies. These ligands are particularly adapted to obtain 3d/4f systems, where invariably the amino fragment is coordinated to the transition metal ion and the phenolate oxygen atoms bridge transition metal and lanthanide ions. Their coordination spheres are completed by donor atoms belonging either to methoxy and aldehyde groups of the Mannich base ligands or to terminal and bridging ancillary ligands. Moreover, robust 3d-4f dinuclear units can be assembled with either bridging ligands or complexes acting as bridging ligands to afford heterometallic complexes with increased nuclearity. The complexes containing one or two paramagnetic ions often exhibit appealing magnetic properties, alone or combined with other physical properties, that essentially arise from large local magnetic anisotropy and magnetic exchange coupling of the metal ions. This chapter provides an overview of recent results on single-molecule magnets (SMMs) based on aminophenol Mannich base ligands that illustrate the scope, state of the art and fruitful dynamism of this field of research.