Estudos fotofísicos e de transferência de energia íon-íon de complexos heterolépticos contendo íons trivalentes de európio e térbio utilizando trifluoroacetilacetonato e hexafluoroacetilacetonato como ligandes principais, trifenilfosfinóxido como ligante auxiliar e trifluoroacetato ou [(difenilfosforil)(etil ou butil)]fosfinóxido como ligantes em ponte

Author(s)

Deborah Asbahr de Lima

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Química
• Defense date: 2019-03-27

Examining board members

Fernando Aparecido Sígoli; Paulo Cesar de Sousa Filho; Marian Rosaly Davolos

• Advisor: Fernando Aparecido Sígoli

Abstract

In this work, the synthesis of a series of [Ln2(hfa)4(µ-tfa)2(H2O)4] dimeric complexes with the formula [Ln(hfa)2(H2O)2-(µ-tfa)2-Ln(hfa)2(H2O)2], where Ln=EuIII, TbIII and LaIII, hfa = hexafluoroacetylacetonate and tfa = trifluoracetate, are reported. The [Tb(hfa)2(H2O)2-(µ-tfa)2-Eu(hfa)2(H2O)2] is temperature-dependent, with maximum relative sensitivity of 2.4 % K-1 at 223 K and it is promising for temperature sensing in the range of 183 K to 323 K. In order to evaluate the effects of bridge ligand in ion-ion energy transfer from TbIII to EuIII, the synthesis of a series of [Ln1(tfaa)3(tppo)-(?-L)-Ln2(tfaa)3(tppo)] homo- or heterodinuclear complexes are reported, where Ln1 and Ln2 may be equal or different from each other, Ln = EuIII, TbIII, GdIII, and the bridge ligand L = [(diphenylphosphoryl)R](diphenyl)phosphine oxide, where R = ethyl or butyl, labeled as dppeo and dppbo, respectively. In the complexes where L = dppeo, the emission lifetime values decrease by replacing one EuIII or TbIII ion in the EuIII-EuIII or TbIII-TbIII complexes by one GdIII. However, in the case of complexes where L=dppbo, the emission lifetime values do not change by replacing one EuIII or TbIII by GdIII. In the excitation spectra of [Tb(tfaa)3(tppo)-(?-L)-Eu(tfaa)3(tppo)] complexes, the presence of 5D4-7F6 transition of TbIII when monitored the 5D0-7F4 emission band of EuIII at 700 nm is an evidence for energy transfer between TbIII and EuIII in these heterodinuclear complexes. Also, the shorter the distance between TbIII and EuIII in these complexes, the greater is EuIII lifetime emission. For TbIII, the opposite occurs. By using a LASER of 488 nm as the light source, the EuIII emission is not likely to occur at 77 K for EuIII-EuIII and EuIII-GdIII complexes. However, for heterodinuclear TbIII-EuIII complexes, intense emission bands of TbIII are observed altogether with lower intensity EuIII emission bands at 77 K, what is a strong evidence for energy transfer from TbIII to EuIII, as well. The [Tb(tfaa)3(tppo)-(?-L)-Eu(tfaa)3(tppo)] complexes exhibited temperature-dependent emission spectra and potentially could be used as ratiometric thermometers. When L = dppeo, the relative sensitivity maximum is 3.3 % K-1 at 323 K and operates in the region between 263 K and 323 K, and when L = dppbo, the relative sensitivity maximum is 3.4 % K-1 to 303 K and operates in the region between 243 K and 323 K (AU)

• FAPESP's process: 17/08098-0 - Study of ion-ion energy transfer in heteroleptic and heterodinuclear complexes of lanthanide ions as a function of donor-acceptor distance
• Grantee: Deborah Asbahr de Lima
• Support Opportunities: Scholarships in Brazil - Master