Composition-Thermometric Properties Correlations in Homodinuclear Eu³⁺ Luminescent Complexes

Area of Science:

• Coordination Chemistry
• Materials Science
• Photophysics

Background:

• Lanthanide complexes are explored for their unique luminescent properties.
• Developing temperature-sensitive luminescent materials is crucial for advanced sensing applications.
• Understanding ligand effects on lanthanide luminescence is key to tuning material performance.

Purpose of the Study:

• To synthesize and characterize homodinuclear lanthanide (Ln3+) complexes.
• To investigate the influence of β-diketonato and N-oxide ligands on thermometric properties.
• To develop and evaluate novel luminescent thermometers based on europium complexes.

Main Methods:

• Synthesis of homodinuclear [Ln2(β-diketonato)6(N-oxide)] complexes (Ln = Eu3+, Gd3+).
• Photoluminescence spectroscopy to study temperature-dependent emission intensity.
• Analysis of thermometric parameters, including integrated intensity (Δ) and relative thermal sensitivity (Sr).
• Investigation of nonradiative deactivation pathways: back energy transfer (BEnT) and ligand-to-metal charge transfer (LMCT).

Main Results:

• Europium complexes exhibit strong temperature-dependent red luminescence (223–373 K).
• Ligand choice significantly impacts thermometer calibration curves and thermal sensitivity.
• Complexes with tta and dbm ligands show active BEnT and LMCT channels.
• Complexes with bta and hfac ligands are primarily governed by LMCT due to higher ligand triplet energy.

Conclusions:

• The developed europium complexes function as effective luminescent thermometers.
• Ligand design is critical for controlling thermometric response and sensitivity.
• Understanding deactivation mechanisms provides a pathway for optimizing luminescent sensor performance.