Spectroscopic and Theoretical Tools Unravel the Thermally-Stabilized Behavior of Eu³⁺-Based Complex Incorporated in Sustainable Urethanesil Film

Author(s)

Caixeta, Fabio Jose ; Saraiva, Leonardo Figueiredo ; de Freitas, Beatriz Damasio ; Onishi, Bruno Seiki Domingos ; Santagneli, Silvia Helena ; Bortoletto-Santos, Ricardo ; Pires, Ana Maria ; Ribeiro, Sidney Jose Lima

• Document type: Journal article
• Source: CHEMISTRY-AN ASIAN JOURNAL; v. N/A, p. 14-pg., 2025-03-12.

Abstract

Despite significant ongoing efforts to develop luminescent rare-earth beta-diketonate complexes, achieving thermal stability remains a persistent challenge. In this study, we present a thermally stable organic-inorganic hybrid (OIH) compound, SiCO-[Eu(tta)3(H2O)2], where tta=thenoyltrifluoroacetonate, Si=3-(triethoxysilyl)propyl isocyanate, and CO=castor oil. Spectroscopic analysis reveals that while [Eu(tta)3(H2O)2] in its powder form undergoes irreversible photoluminescence quenching at 60 degrees C and embedding it in the SiCO polymer preserves its luminescence even after being annealed up to 180 degrees C. Notably, the hybrid film maintains stable emission properties after multiple heating-cooling cycles (29-70 degrees C) and exhibits reversible emission behavior. This finding is attributed to polymer-complex interactions and/or the replacement of water molecules with polymer coordination, resulting in a more rigid environment in the Eu3+ coordination sphere. The thermal dependence of intramolecular energy transfer (IET) indicates that the decrease in Eu3+ luminescence is linked to faster depopulation of the emitting level, driven by non-radiative relaxation and back-energy transfer. This outcome enabled us to strategize approaches to mitigate luminescence quenching in OIH while providing valuable insights into the photophysical properties of these compounds, thus offering a guide towards how we can boost the capabilities of these materials. (AU)

• FAPESP's process: 22/03652-8 - Preparation of PMMA optical fibers and thin films containing optically active centers for application in photonics as luminescent solar concentrators
• Grantee: Fábio José Caixeta
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 23/05718-9 - Multifunctional luminescent films based on down-shifting and up-conversion for anti-counterfeiting application and coated micro-LEDs for display technology
• Grantee: Leonardo Figueiredo Saraiva
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)