Luminescent Er 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-(PhCH)CHO]Er(THF) (1), [(CF)CO]Er(MeSiOH) (2), [(CF)CO]Er[(MeSi)NH] (3), [(CF)CO]Er(CHCH) (4), [(CF)CO]Er(-MeNCHCH) (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.