Lanthanoid/Alkali Metal β-Triketonate Assemblies: A Robust Platform for Efficient NIR Emitters

Area of Science:

• Inorganic Chemistry
• Materials Science
• Luminescence

Background:

• Lanthanoid complexes are crucial for luminescence applications, particularly in the near-infrared (NIR) spectrum.
• Traditional synthesis of efficient lanthanoid emitters often requires complex ligand modifications like perfluorination or deuteration.
• Developing facile synthetic routes to tunable lanthanoid-based luminescent materials remains an active area of research.

Purpose of the Study:

• To synthesize and characterize novel tetranuclear lanthanoid assemblies using a β-triketonate ligand.
• To investigate the luminescent properties of these assemblies, focusing on NIR emission efficiency and excited-state lifetimes.
• To explore the influence of alkali metal ions and lattice solvation on the coordination geometry and luminescence.

Main Methods:

• Reaction of hydrated lanthanoid chlorides with tribenzoylmethane and alkali metal hydroxides.
• Crystallization and structural analysis (X-ray diffraction) of the resulting tetranuclear assemblies.
• Photoluminescence spectroscopy to measure emission spectra, excited-state lifetimes, quantum yields, and sensitization efficiencies.

Main Results:

• Successfully synthesized neutral tetranuclear lanthanoid assemblies with the general formula [Ln(Ae⋅HOEt)(L)4 ]2.
• Observed varied coordination geometries (square antiprism to triangular dodecahedron) dependent on alkali metal and solvation.
• Achieved highly efficient NIR emission for Yb(3+) and Er(3+) assemblies with significantly longer excited-state lifetimes compared to related β-diketonate species.
• Eu(3+) assemblies exhibited bright red emission with performance comparable to β-diketonate complexes.

Conclusions:

• The β-triketonate ligand provides a facile and tunable platform for constructing efficient lanthanoid-based luminescent materials.
• These assemblies demonstrate potential as NIR emitters without requiring complex synthetic modifications.
• The study highlights a promising strategy for developing advanced luminescent materials for various applications.