| Abstract
| - We report here a structural and photophysical study of lanthanide(III) complexes with the di-deprotonated form ofthe bibracchial lariat ether N,N‘-bis(2-salicylaldiminobenzyl)-1,10-diaza-15-crown-5. The X-ray crystal structures of[Ce(L2-2H)](ClO4)·0.5H2O (2) and [Sm(L2-2H)](ClO4)·C3H8O (5b) show the metal ion being nine-coordinated anddeeply buried in the cavity of the dianionic receptor. Thanks to the formation of a pseudomacrocycle through π−πinteraction between one of the phenol rings and one of the benzyl rings, the complexes present a cryptand-likestructure in the solid state. 1H and 13C NMR studies on the La(III) complex point that the solid state structure isessentially maintained in acetonitrile solution. High-resolution laser-excited emission spectra of the crystalline Eu(III)complex demonstrate the presence of several coordination sites arising from different conformations of the crownmoiety. The ligand-to-Eu(III) energy transfer is relatively efficient at low temperature, but back transfer is impliedin the deactivation process, especially at room temperature, because the ligand triplet state lies at very low energy.However, the low energy of the 3ππ* state provides an efficient conversion of the visible light absorbed into near-infrared light emitted by the Nd(III) ion.
- Lanthanide(III) complexes with the bibracchial lariat ether N,N‘-bis(2-salicylaldiminobenzyl)-1,10-diaza-15-crown-5 present a cryptand-like structure due to the formation of a second pseudomacrocycle through π−π interaction between one of the phenol rings and one of the benzyl rings.
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