Estudo das propriedades fotoluminescentes de novos complexos tris B-dicetonatos de íons lantanídeos contendo N-lauroil-2-aminopiridina ou N-lauroil-2-aminopirimidina

Abstract

In the present work, 6 new Eu3+ tris ƒÀ-diketonate complexes were synthesized with the amides nl2ap (N-lauroyl-2-aminopyridine) and nl2apm (N-lauroyl-2-aminopyrimidine) and their 6 analogs complexes with Gd3+ in order to investigate the influence of normal vibrations of the lauroyl group (C11H23) in the non-radiative spontaneous decay rate. The Ln(ƒÀ-diketonate)3nl2ap and Ln(ƒÀ-diketonate)3nl2apm complexes, with Ln = Eu3+ and Gd3+; ƒÀ-dicetonate = btfa (3-benzoyl-1,1,1-trifluoroacetonate), tta (2-tenoyltrifluoroacetonate) and dbm (dibenzoylmethanate), were synthesized starting from the tris ƒÀ-diketonate aquacomplexes precursors. The complexes were characterized by complexometric titration, IR absorption, thermogravimetric analysis and UV-Vis reflectance. The luminescent properties were investigated, with complexes presenting high values of intrinsic quantum yield [..........(%)] in relation to aquacomplexes, highlighting Eu(btfa)3nl2apm with .......... = 68.5%. The complexes presented the 5D0 ¨7F2 temperature sensitive transition, eading to higher rates of radioactive decay in these transitions at room temperature. The Eu(btfa)3nl2ap presented ................ below the literature Eu(btfa)3na2ap complex, an unexpected result due to the presence of more C.H modes in the first complex. It was not possible to correlate the non-radiative rates with the energy gap and resonant-inductive energy transfer mechanism due to the large energy gap of the 5D0 emitter level.