Intramolecular energy transfer processes in lanthanide ²-diketone complexes investigated by time-resolved spectroscopy

• Grant number: 22/13386-3
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: April 24, 2023
• End date: May 04, 2023
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Inorganic Chemistry
• Principal Investigator: Hermi Felinto de Brito
• Grantee: Lucca Blois Guimarães
• Supervisor: Peter Gilch
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Heinrich Heine University Düsseldorf (HHU), Germany
• Associated to the scholarship: 20/16795-6 - Intramolecular energy transfer processes in rare-earth beta-diketonate complexes investigated by means of transient absorption spectroscopy, BP.DD

Abstract

The understanding of intramolecular energy transfer processes in lanthanide coordination compounds is of utmost importance for the development of numerous fields of application such as: sensors, safety markers, OLEDs, nanothermometers etc. In this context, the transient absorption technique is an extremely powerful technique to probe the "ligand-character" non-emitting levels such as the exited singlet and triplet states S1 and T1 that are thought to be the most relevant for the intramolecular energy transfer process. Although various theoretical models and experimental transient studies have been carried out in the last decades, almost none of the experimental works focuses on the most widely used ligand class for lanthanide complexes: the ²-diketonates. That being, we aim to explore the transient absorption spectra of several Eu3+, La3+ ²-diketonate complexes to study the excited state dynamics, including the ligand-to-metal energy transfer processes. We have chosen the 2-thenoyltrifluoroacetone (Htta) and 1,10-phenanthroline (phen) ligands to prepare the [Eu(NO3)3(phen)2] and Q[Eu(tta)4] (Q: tetrabutylammonium and 1-butyl-3-methylimidazolium).Additionally, we expect to study the metal-to-metal energy transfer by obtaining the time-resolved emission and absorption of the Q[Tb1-xEux(ntfa)4] (ntfa: 2-naphotyltrifluoroacetone, Q: tetrabutylammonium, 1-butyl-3-methylimidazolium), since the ligand role in assisting this ET process is still somewhat obscure. Combined with the time-resolved emission data, it may be possible to model almost all of the IET rates using the appropriate differential rate equation system. The data that can be obtained from such time-resolved measurements such as the ligand S1 ’ T1 intersystem crossing rate and internal conversion rates are crucial for obtaining and estimating parameters like the energy transfer quantum yield or even the absolute quantum yield. However, their report in the literature is exceptionally scarce. In this context, this research proposal aims to measure and report essential data for the field of lanthanide coordination compounds. (AU)