Luminescent Er 3+ based single molecule magnets with fluorinated alkoxide or aryloxide ligands

We report the synthesis, structures, and magnetic and luminescence properties of a series of new mono- and dinuclear Er complexes derived from sterically demanding aryloxide and fluorinated alkoxide ligands: [4- Bu-2,6-(Ph CH) C H O] Er(THF) (1), [(C F ) CO] Er(Me SiOH) (2), [(C F ) CO] Er[(Me Si) NH] (3), [(C F ) CO] Er(C H CH ) (4), [(C F ) CO] Er( -Me NC H CH ) (5) and {[Ph(CF ) CO] Er(μ -OC(CF ) Ph)} (6). In compounds 1, 2, and 4, the Er ion is four-coordinated and adopts a distorted trigonal pyramidal geometry, while in 3, 5, and 6, the coordination geometry of Er is impacted by the presence of several relatively short Er⋯F distances, making them rather 6-coordinated. All compounds behave as field-induced Single Molecule Magnets (SMMs) and exhibit an Er characteristic near infrared (NIR) emission associated with the I → I transition with a remarkably long lifetime going up to 73 μs, which makes them multifunctional luminescent SMMs. The deconvolution of the NIR emission spectra allowed us to provide a direct probe of the crystal field splitting in these compounds, which was correlated with magnetic data.