Unraveling the Up-Conversion Mechanism Involved in the Intense Red Emission of a Mononuclear Er^III Complex

Author(s)

Gil, Yolimar ; de Santana, Ricardo Costa ; Meritzio, Leonnam Gotardo ; Vega, Andres ; Fuentealba, Pablo ; Spodine, Evgenia

• Document type: Journal article
• Source: CHEMISTRY-AN ASIAN JOURNAL; v. N/A, p. 6-pg., 2025-06-10.

Abstract

The scarcity of up-conversion (UC) luminescence studies involving LnIII molecular complexes mainly arises from the challenge of designing a coordination sphere that minimizes the interactions of the metal centers with high-energy oscillators. By using a combination of reported strategies to reduce these interactions, we synthesized and characterized a mononuclear complex, Er(tta)3(bipy) (tta: thenoyltrifluoroacetone; bipy: 2,2 '-bipyridine) (Er-TB). Upon 980 nm laser excitation at room temperature, this complex gives rise to the challenging up-converted red (4F9/2 -> 4I15/2) band, besides the bluish-green (2H11/2 -> 4I15/2) and green (4S3/2 -> 4I15/2) ones, as well as a downshifted NIR (4I13/2 -> 4I15/2) emission. Interestingly, a high intensity of the red emission band and unprecedented luminescence lifetime values (448 mu s for green and 775 mu s for red emission) were achieved. A detailed analysis of the available data allows us to unravel the probable UC mechanism, which results in a dominant energy transfer up-conversion (ETU) mechanism via three-photon absorption, while a cross-relaxation (CR) process for the intense red emission is proposed. Besides affording a design strategy to achieve UC luminescence in ErIII complexes, this study opens the door to the design of other lanthanide-based molecular UC systems, expanding the scope of these materials in the UC luminescence field. (AU)

• FAPESP's process: 19/21770-5 - Luminescent materials incorporated to glasses: new composites for application in safety lighting and radiation detection
• Grantee: Leonnam Gotardo Merizio
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass
• Grantee: Edgar Dutra Zanotto
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 24/15684-7 - Persistent luminescence via up-conversion: Modulation of emission phenomena in multifunctional glass composites
• Grantee: Leonnam Gotardo Merizio
• Support Opportunities: Scholarships in Brazil - Support Program for Fixating Young Doctors