Banca de DEFESA: ALEX SANDRO NASCIMENTO DA SILVA FILHO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ALEX SANDRO NASCIMENTO DA SILVA FILHO
DATE: 03/03/2023
TIME: 09:00
LOCAL: Departamento de Química
TITLE:

THEORETICAL STUDY OF THE EFFECTS OF ANIONS ON EUROPIUM COMPLEXES WITH 12-CROWN-4 AND 1,10-PHENANTROLINE

KEY WORDS:

lanthanide, B3LYP, M06-2X

PAGES: 65
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SPECIALTY: Físico Química Inorgânica
SUMMARY:

The study of the effects of counter-ions of [Eu(12C4)(phen)₂(X)_n]^3-n on the europium emitting spectrum is studied theoretically. X = F^-, Cl^-, Br^-, SCN^-, NO₃^-, ClO₄^-. In the experimental study it is reported in the excitation and emission spectrum polarizability events of the anions, in which there is the maximum excitation shift and the reduction of quantum efficiency respectively. In addition to considering [Eu(12C4)(fen)₂]³⁺ a specific sensor of nitrate ions when in water. Based on this, calculations were performed with two coordination forms of the ligand X in B3LYP and M06-2X methods, defined as superior (S) and lateral (L) coordination. Then a study of the solvation process of the optimized structures. Finally, the triplet and singlet states by LC-ωPBE in the M06-2X geometries are studied. The results describe that lateral addition favors the complexation process, but when in water the F- and Br- anions invert, considering the formation of the higher form. The ion exchange for synthesis of [Eu(12C4)(phen)₂NO₃]²⁺ by the other complexes describes that synthesis of the lateral form is more likely to be formed than the top one. But the ion exchange with F^- does not occur. Regarding the excited states, two probable mechanisms of electron transfer in the complexes are described, in which, starting from the energy differences of the ligand-euron states. It relates that the non-radiative rate reduces with the loss of symmetry of [Eu(12C4)(phen)₂(X)_n]^3-n upon addition of the ligand and the emission mechanism I (T₂ → T₁ → ⁵D₀ or T₁ → ⁵D₀). This process is evidenced in the complex with [Eu(12C4)(phen)2NO3]2+. While the radiative rate and by the smaller radius (structural stability) and polarizability of the ligand. These parameters are more significant when they occur in the most stable coordination form.

COMMITTEE MEMBERS:
Interno - CRISTIANO COSTA BASTOS
Externa à Instituição - KEYLA MIRELLY NUNES DE SOUZA
Presidente - MONICA FREIRE BELIAN