DESENVOLVIMENTO DE UM NOVO MARCADOR LUMINESCENTE PARAMICROCISTINA-LR: um estudo teórico. / DEVELOPMENT OF A NEW luminescent PARAMICROCISTINA-LR: a theoretical study.

AUTOR(ES)

Júlio Gomes dos Santos

DATA DE PUBLICAÇÃO

2010

RESUMO

In this work we describe a theoretical study of lanthanide complexes with macrocyclic ligands. Spectroscopic properties of the cryptate [EuÌ(bipy)2py(CO2Et)2]3+.2H2O were investigated with semiempirical methodologies such as Sparkle, INDO/S-CIS, Judd- Ofelt model as well as Maltas models implemented in LUMPAC (Luminescence Package). This computational package has turned viable the purely theoretical design of highly luminescent lanthanide complexes. We initially looked for a calculation method that better reproduced the absorption spectrum of the cryptate, finding out that AM1-p was the best candidate. This method used Sparkle/AM1 together with INDO/S-CIS. In the sequence we tested LUMPACs efficacy using a series of trisbipyridines and observed that the theoretical results were in good agreement to the experimental ones. Finally, we studied the cryptate EuÌ(bipy)2py(CO2Et)2]3+.2H2O and its derivatives. The theoretical intensity parameters (= 2, 4, 6) of the cryptates revealed that Eu3+ ion lies in a weakly polarizable environment. The transfer rates clearly indicated that the energy transfer occurs predominantly from the ligands triplet state to 5D1 and 5D0 levels belonging to Eu3+ ion. The low quantum yield values observed for all cryptates were probably due to a poor resonance between the ligands triplet state and the emitting level from Eu3+. The most promising substituted cryptate was found to be [EuÌ3]3+, however the calculation of a cryptate conjugated with microcystin-LR did not show better results. In summary the results as a whole evidenced that the methodology employed is promising in predicting spectroscopic properties of lanthanide complexes.

ASSUNTO(S)

lanthanides quimica luminescence lmct sparkle/am1 luminescência lantanídeos criptatos cryptates lmct sparkle/am1

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