Molecular Lanthanide Switches for Magnetism and Photoluminescence

Abstract

Solvation of [(CNT)Ln(η8‐COT)] (Ln=La, Ce, Nd, Tb, Er; CNT=cyclononatetraenyl, i.e., C9H9−; COT=cyclooctatetraendiid, i.e., C8H82−) complexes with tetrahydrofuran (THF) gives rise to neutral [(η4‐CNT)Ln(thf)2(η8‐COT)] (Ln=La, Ce) and ionic [Ln(thf)x(η8‐COT)][CNT] (x=4 (Ce, Nd, Tb), 3 (Er)) species in a solid‐to‐solid transformation. Due to the severe distortion of the ligand sphere upon solvation, these species act as switchable luminophores and single‐molecule magnets. The desolvation of the coordinated solvents can be triggered by applying a dynamic vacuum, as well as a temperature gradient stimulus. Raman spectroscopic investigations revealed fast and fully reversible solvation and desolvation processes. Moreover, we also show that a Nd:YAG laser can induce the necessary temperature gradient for a self‐sufficient switching process of the Ce(III) analogue in a spatially resolved manner.

Cycloheptatrienyl-Bridged Triple-Decker Complexes

“…As often observed, the Raman exponent is found to be smaller than expected for Kramer ions. 12,58 To corroborate that the anisotropic character is of molecular origin, we have performed magnetic dilution studies by doping 10% (molar ratio) of 2-Er into the diamagnetic 2-Y analogue, producing 2-Er 10% @2-Y (see the experimental section in the SI for details). AC studies reveal a maximum between 11 and 28 K in the χ″ M (ν) data (Figure S29).…”

Mono-cyclononatetraenyl lanthanide complexes

“…In particular, the Ln-Cnt vibrational bands are clearly observable (see above). As seen for [(Z 9 -CNT)Ln III (Z 8 -COT)] (Ln = Ce, Nd, Tb, Er), 16 this effect offers some potential with respect to switchable materials.…”

“…Since crystals of the two compounds were reproducibly twinned, structural refinement was performed after twin integration with X-area. 25 The cationic units in both cases are pentagonalbipyramidal coordinated [Ln III (Z 3 -BH 4 ) 2 (thf Since the related full displacement of the Cnt ring with THF in the ionic compounds [Ln III (thf) x (Z 8 -COT)][CNT] (x = 4 (Ce, Nd, Tb), 3 (Er)) is fully reversible, 16 we were interested to study the back reaction of 3 and 4 to compounds 1 and 2. After drying the crystals of the THF adducts 3 and 4 in high vacuum, Raman spectra of the isolated solids were obtained analogous to those of the unsolvated compounds 1 and 2.…”

It's not just the size that matters: crystal engineering of lanthanide-based coordination polymers

“…For instance, no PL was detected in solid state from the sandwich complex of La with h 8 -Cot and h 9 -cyclononatetraenyl ligands. 43 On the other hand, PL was also not detected from the homologous Ce III compound. The latter gained, however, a Ce III -typical emission (with 2 D / 2 F 5/2 transition at 500 nm) aer replacement of cyclononatetraenyl by coordinated solvent (thf) molecules.…”