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336 Materials and Nanotechnology | Progress Report
display. In the field of biomarker, these com-
pounds linked with biological parts. At this
time, it was synthesized new complexes of eu-
ropium ο-diketonate with tetracycline,pirox-
ican and fluoxetine as ligand. IR spectra of the
Eu(III) complexes show two strong absorption
bands at ~1597 and ~1566 cm-1 attributed to
οs(C=O) and οas(C=O) vibrational stretching
modes, suggesting that the ο-diketonate li-
gand acts as chelate ligand. SEM image showed
particles rounded with grain size lower than
10 nm (Fig 3). The emission spectrum of euro-
pium complexes, in the solid state, recorded
in the range of 520 to 720 nm at liquid nitro-
gen temperature, under excitation at ο-diketo-
nate transitions (~350 nm) is shown in Fig. 62.
This emission spectrum exhibits some charac-
Figure 62. Luminescent biomarkers for chem-
icals detection in biologic fluids. teristics such as narrow emission bands that
are assigned to the 4f6-4f6 transitions of Eu-
(III) ion, attributed to the emitting 5D0 level to
Luminescent materials containing trivalent the 7FJ (J = 0, 1, 2, or 4) levels, where the most
rare earth (RE3+) complexes with ο-diketo- intense corresponds to 5D0ο7F2 transition
nate ligands have been intensively studied in taking place around 613 nm. An important
recent years. The RE3+ compounds present feature to be observed is the nonexistence of
some characteristics such as narrow emission broaden bands arising from the ο-diketonate
bands in the UV-Vis region, large Stokes shift centered transitions, indicating that intramo-
and the antenna effect that enhance the over- lecular energy transfer from the ο-diketonate
all quantum efficiency. As a result, these com- ligands to the Eu(III) ion is operative.
plexes have found wide applications as lumi-
nescent markers, photoluminescent sensors,
electroluminescent devices and multicolor
Instituto de Pesquisas Energéticas e Nucleares
