Structural investigation of lanthanide compounds using the Electronic Paramagnetic Resonance (EPR) technique as a function of the ligand field

• Grant number: 24/02129-5
• Support Opportunities: Regular Research Grants
• Start date: October 01, 2024
• End date: September 30, 2026
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Inorganic Chemistry
• Agreement: CNPq
• Principal Investigator: Hermi Felinto de Brito
• Grantee: Hermi Felinto de Brito
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 21/08111-2 - Development of rare earth based light converters: luminescent markers, optical sensors, and amplifiers, AP.TEM
• Associated scholarship(s): 24/12789-2 - Structural investigation of lanthanide compounds using the Electronic Paramagnetic Resonance (EPR) technique as a function of the ligand field, BP.JD

Abstract

Electron Paramagnetic Resonance (EPR) is a technique applied in several areas of science, from dosimetry, structural determination of proteins and free radical generation studies, and also acts as a very efficient technique when it comes to the study of paramagnetic species. In the study of luminescent phenomena, it can be used for the determination of ionic species involved in luminescence mechanisms, for qualitative and in some cases quantitative observation of defect formation in luminescent matrices. In this project, EPR will be the main technique for investigating the effect of the change in the ligand field in the EPR signal of the Gd+3 ion and correlating these changes with the field strength, measured using the Eu3+ as a spectroscopic probe. The main focus of this project is the study of the structure of lanthanide compounds by means of the Electron Paramagnetic Resonance (EPR) technique as a function of the chemical environment around the trivalent (Gd3+) or divalent (Eu2+) lanthanide ions that have the 4f7 electron configuration. Therefore, the proposal also involves the synthesis of different tetrakis complexes of Q[Ln(²-dicetonate)4] lanthanides with the ligand ²-diketone (L: 2-tenoyltrifluoroacetonate (tta), dibenzoylmethanate (dbm) and acetylacetonate (acac)) and the contraction (Q+: imidazolium) whose luminescent properties and ligand field effects have been studied. In this case, the ²-diketon complexes with Gd3+ will be doped with the trivalent europium ion (Eu3+). Thus, the lanthanide complexes will be investigated by EPR, with the support of the computational simulation of the EPR spectra obtained using the MATLAB platform, in order to optimize the spectroscopic parameters of each lanthanide complex and correlate them with the structures known due to the perturbation of the ligand field. This will enable the construction of a calibration curve that correlates the measurement of the gyromagnetic constant (g) obtained via the EPR signal as a function of the unfolding ligand field of the complex. In addition, from the determination of the calibration curve it will be possible to study the influence of the ligand field of other systems such as inorganic matrices, bulk, nanoparticles and films, using the Gd3+ or Eu2+ lanthanide ions as a structural probe based on Paramagnetic Electron Resonance (EPR) spectroscopy. Finally, the present proposal uses the EPR spectroscopy technique that will corroborate the optical properties of rare earth-based luminescent materials. (AU)