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 3+ complexes derived from sterically demanding aryloxide and fluorinated alkoxide ligands: [4- t Bu-2,6-(Ph 2 CH) 2 C 6 H 2 O] 3 Er(THF) (1), [(C 6 F 5 ) 3 CO] 3 Er(Me 3 SiOH) (2), [(C 6 F 5 ) 3 CO] 3 Er[(Me 3 Si) 2 NH] (3), [(C 6 F 5 ) 3 CO] 3 Er(C 6 H 5 CH 3 ) (4), [(C 6 F 5 ) 3 CO] 3 Er( o -Me 2 NC 6 H 4 CH 3 ) (5) and {[Ph(CF 3 ) 2 CO] 2 Er(μ 2 -OC(CF 3 ) 2 Ph)} 2 (6). In compounds 1, 2, and 4, the Er 3+ ion is four-coordinated and adopts a distorted trigonal pyramidal geometry, while in 3, 5, and 6, the coordination geometry of Er 3+ 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 3+ characteristic near infrared (NIR) emission associated with the 4 I 13/2 → 4 I 15/2 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.