Intramolecular energy transfer and its influence on the overall quantum yields of Eu3+ and Tb3+ chelates with dimethyl(phenylsulfonyl)amidophosphate ligands

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2025-01, Vol.324, p.124875, Article 124875
• Main Authors: Carneiro Neto, Albano N., Nasalska, Justyna, Gawryszewska, Paula, Trush, Viktor A., Sokolnicki, Jerzy, Malta, Oscar L., Legendziewicz, Janina
• Format: Article
• Language: English
• Subjects: Energy transfer rates; Luminescence; Quantum yields; Sulfonylamidophosphates; Theoretical calculations
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2024.124875

[Display omitted] •The Lewis base co-ligands enhance the efficiency of intramolecular energy transfer.•For Tb chelates, IET occurs mainly from S1 state involving higher Tb excited levels.•IET in Eu3+ chelates is influenced via T1 ligand state.•The exchange mechanism is the most effective interaction for Eu and Tb chelates.•The ability to accurately predict quantum yield has been demonstrated. Lanthanide chelates with dimethyl(phenylsulfonyl)amidophosphate (labeled as HSP) and Lewis base ligands (bpy = 2,2;-bipyridine and phen = 1,10-phenanthroline) of formula Na[Ln(SP)4] (1Ln), [Ln(SP)3bpy] (2Ln); [Ln(SP)3phen] (3Ln) (Ln = Eu3+, Gd3+, Tb3+ and Lu3+) were obtained and characterized by the X-ray, photoluminescence spectroscopy at 293 and 77 K as well as by intrinsic (QLnLn) and overall (QLnL) luminescence quantum yields. These phosphors manifest a very strong emission after excitation in the UV range of the molecular singlet states (S1) and two of them have very high QLnL values (Eu3+ and Tb3+ chelates of the type 2Ln and 3Ln). The dynamics of the excited states are discussed based on the intramolecular energy transfer theory, considering the dipole–dipole, the dipole-multipole and the exchange mechanisms. From the calculated energy transfer rates, a rate equation model was constructed and, thus, the theoretical QLnL can be obtained. A good correlation between the experimentally determined and theoretically calculated QLnL values was achieved, with the triplet state (T1) playing a predominant role in the energy transfer process for Eu3+ compounds, while the sensitization for Tb3+ compounds is dominated by the energy transfer rates from the singlet state (S1).