Characterization and Luminescence Properties of Lanthanide-Based Polynuclear Complexes Nanoaggregates
Résumé
For the first time, hexanuclear complexes with general chem. formula [Ln6O(OH)8(NO3)6(H2O)n]2+ with n = 12 for Ln = Sm-Lu and Y and n = 14 for Ln = Pr and Nd were stabilized as nanoaggregates in ethylene glycol (EG). These unprecedented nanoaggregates were structurally characterized by 89Y and 1H NMR spectroscopy, UV-vis absorption and luminescence spectroscopies, electrospray ionization mass spectrometry, diffusion ordered spectroscopy, transmission electron microscopy, and dynamic light scattering. These nanoaggregates present a 200 nm mean solvodynamic diam. In these nanoaggregates, hexanuclear complexes are isolated and solvated by EG mols. The replacement of ethylene glycol by 2-hydroxybenzyl alc. provides new nanoaggregates that present an antenna effect toward lanthanide ions. This results in a significant enhancement of the luminescence properties of the aggregates and demonstrates the suitability of the strategy for obtaining highly tunable luminescent solns.