Lanthanide‐Functionalized Water‐Soluble Ionic Motors: Synergetically Regulated Rotary Motion by Allostery and Triplet Sensitization

Abstract Molecular motors, based on overcrowded alkenes (L) serving as ligands to chelate lanthanide nitrate, afford the first lanthanide‐functionalized water‐soluble ionic compound [L₂‐Ln(NO₃)₂(H₂O)₂]·NO₃ (LnL₂). Benefitting from the “pull–push” feature of L together with ³LMCT from L to Ln^III, irradiation with visible light not only drives photochemical isomerization but also induces energy transfer from L to Ln^III, decreasing their intensity of low‐energy ³LMCT (ligand‐to‐metal triplet energy transfer) absorptions and sensitizing the Ln‐based luminescence. Thus, the typical Eu^III‐based luminescence of EuL₂ favors tracing its movement by time‐resolved luminescence, and temperature‐dependent luminescence renders it possibly to be used as potential luminescent thermometers. Very excitingly, besides a contraction of the stator by Ln–L interactions on decreasing the steric hindrance on the “fjord region,” the efficiency of intramolecular ³LMCT sensitization synergetically regulates the rotary motion of lanthanide‐complexed motors in thermal helix inversion steps.