Maria Claudia França da Cunha Felinto

Verified email at ipen.br

Professor Dr / Comissão Nacional de Energia Nuclear
Instituto de Pesquisas Energéticas e Nucleares



                               

http://researchid.co/neves2019
80

Scopus Publications

2452

Google Scholar Citations

28

Google Scholar h-index

50

Google Scholar i10-index

Scopus Publications

  • Luminescence properties of the Ln–EDTA complexes covalently linked to the chitosan biopolymers containing β-diketonate as antenna ligands
    Israel F. Costa, Gilvan P. Pires, José Geraldo P. Espínola, Hermi F. Brito, Maria Claudia F.C. Felinto, Wagner M. Faustino, and Ercules E.S. Teotonio

    Luminescence, ISSN: 15227235, eISSN: 15227243, Pages: 365-372, Published: 1 May 2020 Wiley
    This paper reports on the preparation, characterization, and photoluminescence properties of novel hybrid materials, in which the EDTA-Ln-L complexes (where L: H2 O, acac, bzac, dbm, and tta ligands, and Ln: Eu, Gd, and Tb) were covalently linked to the precursor medium molecular weight chitosan surface (CS) matrices or on the chitosan surfaces previously crosslinked with epichlorohydrin (CSech). The emission spectra of these materials were characterized by intraconfigurational-4fN transitions centred on the Eu3+ and Tb3+ ions. Some broad bands from the polymeric matrix were also observed in the emission spectra, however the relative intensities of the intraconfigurational bands increased significantly for systems containing diketonate ligands when the antenna effect became more efficient. The values of the radiative rates (Arad ) were higher for crosslinked hybrid systems with epichlorohydrin, while nonradiative rates (Anrad ) presented the opposite behaviour. These data contributed to an increase in the values of emission quantum efficiency (η) for crosslinked materials. The effect of the modification process and antenna ligand on the values of intensities, intensity parameters Ω2 e Ω4 of the Eu3+ complexes were also investigated. The results showed that the crosslinked biopolymer surfaces have great potential for applications in molecular devices light converters.

  • Synthesis, Structure Study, First-Principles Investigations and Luminescence Properties of Europium and Terbium Complexes
    Bakhat Ali, Helio A. Stefani, Muhammad Imran, Ahmad Irfan, Mohammed A. Assiri, Maria Claudia F. C. Felinto, Muhammad Khalid, and Abdullah G. Al-Sehemi

    Journal of Fluorescence, ISSN: 10530509, eISSN: 15734994, Published: 2020 Springer Science and Business Media LLC
    The synthesis of 1-benzyl-2-((2-Aminoethyl) amino)-5-oxopyrrolidine-3,4-diyl diacetate (boad), an oxopyrrolidine type ligand; designed to coordinate lanthanides (Eu3+ and Tb3+) to get luminescent material. The target complexes showed good photoluminescence properties, which indicate that this type of compound can be used as sensitizers having luminescence for the green (Tb3+) and red (Eu3+) emission. The obtained results revealed that sensitizer efficiency can be improved by adding ligands like acac (Eu(acac)3, which has also enhanced the luminescence quantum output and period for Eu3+ ions. The ground state geometries were developed by using density functional theory at B3LYP/6-31G** level. The charge transfer analysis and electronic properties were performed. The Europium and Terbium complexes formation with boad ligand was explored based on molecular electrostatic potential, MDC-q charges, and frontier molecular orbitals (FMOs) analysis.

  • Development of highly luminescent PMMA films doped with Eu3+β-diketonate coordinated on ancillary ligand
    Francisco, Felinto, Brito, Teotonio and Malta

    Journal of Materials Science: Materials in Electronics, ISSN: 09574522, eISSN: 1573482X, Pages: 16922-16931, Published: 1 September 2019 Springer New York
    In this work, [Eu(tta)3(4-picNO)2] and [Eu(dbm)3(4-picNO)] complexes were incorporated on different concentrations (x = 1, 3, 5, 10 and 15%) in PMMA polymeric matrix (4-picNO: 4-Methylpyridine N-oxide) by the solvent casting method, yielding transparent and highly luminescent polymeric films. These materials were analyzed by X-ray diffraction, scanning electron microscopy and by energy dispersive, ultraviolet–visible spectroscopy, luminescence and vacuum ultraviolet–ultraviolet spectroscopies. The luminescence spectra of doped PMMA films are in agreement with an efficient intramolecular diketonate (tta) ligand-to-europium energy transfer. Furthermore, the values of experimental intensity parameters (Ω2,4) for luminescent polymeric materials were quite similar to those ones for isolated complexes, indicating that there is a homogeneous dispersion of Eu3+ complexes in the polymeric matrix, preserving their chemical and structural features. These behavior were also observed from the CIE diagram that show great similarity between the (x,y) coordinates for the doped PMMA samples compared to the isolated β-diketonate complexes with a reddish color tuning. The photostability investigation of the doped PMMA polymeric films and Eu3+ complexes has been also reported.

  • Investigation on the formation of highly luminescent β-diketone-Ln(III)-EDTA water-soluble complexes
    Haryane R.M. Silva, Wagner M. Faustino, Ercules E.S. Teotonio, Hermi F. Brito, Oscar L. Malta and Maria Cláudia F.C. Felinto

    Journal of Luminescence, ISSN: 00222313, Volume: 207, Pages: 182-187, Published: March 2019 Elsevier B.V.
    Abstract Three new β-diketone–Ln-EDTA (β-diketone = TTA, BTFA, ACAC; Ln=Eu3+ and Tb3+) water-soluble complexes were prepared, and their photophysical properties were investigated in aqueous solutions and compared with the Eu–EDTA complex. A very strong red and green luminescence was observed by the addition of ligands to the aqueous solutions of the Eu–EDTA and Tb–EDTA complexes, respectively, due to the formation of water-soluble β-diketone–Ln–EDTA complexes. To confirm the formation and stoichiometry of the new β-diketone–Ln–EDTA complex, the Judd–Ofelt intensity parameters Ω2 for Eu3+ complexes and the band width at half height (Δλ) for Tb3+ complexes were used. The dependence of these parameters on the addition of the β-diketone strongly suggests that only one β-diketonate ligand is in the first coordination sphere of the β-diketone–Ln–EDTA complexes. These new Eu3+ and Tb3+ systems may act as red and green optical markers for bioassay or bioimaging.

  • Tuning Emitting Color of Electroluminescent Devices Containing Tris(2‑acyl‑1,3‑indandionate)aluminum(III) Complexes as Emitting Layers
    Israel Costa, Jandeilson Moura, Rian Aderne, Harold Avila, Marco Cremona, Hermi Brito, Maria Cláudia Felinto, Wagner Faustino, and Ercules Teotonio

    Journal of the Brazilian Chemical Society, ISSN: 01035053, eISSN: 16784790, Pages: 1647-1656, Published: 2019 Sociedade Brasileira de Quimica (SBQ)
    In this study, a novel type of tris(2-acyl-1,3-indandione)-aluminum(III) coordination compounds of the general formula [Al(acind)3]H2O, where 2-acyl-1,3-indandione (acind), 2-acetyl1,3-indandione (aind), 2-benzoyl-1,3-indandione (bind), and 4-methyl-2-benzoyl-1,3-indandione (mbind), were synthesized and characterized by elemental analysis (CHN), Fourier transform infrared (FTIR) and nuclear magnetic resonance (H NMR) spectroscopies, thermal analysis (TG/DTG and DTA), and optical absorption spectroscopy in the UV-Vis region. These compounds present remarkably high green luminescence in powder and in thin-film forms. However, when these compounds are applied in glass/ITO/β-NPB/spiro-2CBP/[Al(acind)3]/Al and glass/ITO/β-NPB/ [Al(acind)3]/LiF/Al electroluminescent devices, where spiro-2CBP is 2,7-bis(carbazol-9-yl)-9,9spirobifluorene and β-NPB is N,N’-bis(naphthalen-2-yl)-N,N’-bis(phenyl)-benzidine, the emission color tuned from green to red, reflecting a change from the direct charge recombination in the emitting layer of the [Al(acind)3] complexes to an exciplex-based emission in which [Al(acind)3] complexes and spiro 2-CBP acted as acceptor and donor, respectively. These results suggest that [Al(acind)3] complexes have potential applications as molecular light converter materials for fabricating new electroluminescent devices.

  • Odd-Even Effect on Luminescence Properties of Europium Aliphatic Dicarboxylate Complexes
    Israel P. Assunção, Albano N. Carneiro Neto, Renaldo T. Moura, Cássio C. S. Pedroso, Ivan G. N. Silva, Maria C. F. C. Felinto, Ercules E. S. Teotonio, Oscar L. Malta and Hermi F. Brito

    ChemPhysChem, ISSN: 14394235, eISSN: 14397641, Pages: 1931-1940, Published: 2019 Wiley-VCH
    The odd-even effect in luminescent [Eu₂(L)₃(H₂O)x]•y(H2O) complexes with aliphatic dicarboxylate ligands (L: OXA, MAL, SUC, GLU, ADP, PIM, SUB, AZL, SEB, UND, and DOD, where x = 2-6 and y = 0-4), prepared by the precipitation method, was observed for the first time in lanthanide compounds. The final dehydration temperatures of the Eu³+ complexes show a zigzag pattern as a function of the carbon chain size of the dicarboxylate ligands, leading to the so-called odd-even effect. The FTIR data confirmed the ligand-metal coordination via the mixed mode of bridge-chelate coordination, except for the Eu³+-oxalate complex. XRD results point out to highly crystalline materials belonging to the monoclinic system. The odd-even effect on the 4f-4f luminescence intensity parameters (Ω₂ and Ω₄) was explained by using an extension of the Dynamic Coupling mechanism, herein named the Ghost-Atom model. In this method, the long-range polarizabilities (α*) were simulated by a Ghost-Atom located at the middle of each ligand chain. The values of α* were estimated using the localized molecular orbital approach. The emission intrinsic quantum yield (Q_Ln^Ln) of the Eu³+ complexes also presented an the odd-even effect, successfully explained in terms of the zigzag behavior showed by the Ω₂ and Ω₄ intensity parameters. Luminescence quenching due to water molecules in the first coordination sphere was discussed and rationalized.

  • Modeling intramolecular energy transfer in lanthanide chelates: A critical review and recent advances
    Albano N. Carneiro Neto, Ercules E.S. Teotonio, Gilberto F. de Sá, Hermi F. Brito, Janina Legendziewicz, Luís D. Carlos, Maria Claudia F.C. Felinto, Paula Gawryszewska, Renaldo T. Moura, Ricardo L. Longo, Wagner M. Faustino, and Oscar L. Malta

    Handbook on the Physics and Chemistry of Rare Earths, ISSN: 01681273, Pages: 55-162, Published: 2019 Elsevier

  • Persistent luminescence of inorganic nanophosphors prepared by wet-chemical synthesis
    Everton Bonturim, Leonnam Gotardo Merízio, Roberto dos Reis, Hermi Felinto Brito, Lucas Carvalho Veloso Rodrigues and Maria Claudia França Cunha Felinto

    Journal of Alloys and Compounds, ISSN: 09258388, Volume: 732, Pages: 705-715, Published: 25 January 2018 Elsevier Ltd
    Abstract The synthesis of efficient nanosized persistent luminescence materials remains a challenge for the community. Paradoxically, due to the dependence of the point lattice defects and the persistent luminescence efficiency, the control of the defect formation, favorable when the materials are prepared at high temperatures, normally leads to particle growth and sintering. In this work, efficient nanosized rare earth doped disilicates Sr2MgSi2O7:Eu2+,Dy3+ were synthesized via three different wet-chemical methods taking advantages of the microwave-assisted reduction process as a support step to produce high-quality polycrystalline materials. The crystallite size of the sample showed to be smaller when the decomposition temperature of the precursors is higher and close to the phase formation energy. The excitation VUV spectroscopy indicated that despite being nanocrystalline, the materials optical band gap has just a small difference compared one to another. The reduction of Eu3+ to Eu2+ was successfully obtained, since the f-d interconfigurational transitions of Eu2+ 4f65d1→4f7 emission were observed in the blue region of the spectra. The persistent luminescence efficiency measured through its lasting decay time was close to the commercial materials references and with the advantage of having size control during the synthesis method that can lead to the size dependent applications of photonic materials.

  • Synthesis and photoluminescence properties of [Eu(dbm)3·PX] and [Eu(acac)3·PX] complexes
    Thelma A. Kovacs, Maria Cláudia F.C. Felinto, Tiago B. Paolini, Bakhat Ali, Liana K.O. Nakamura, Ercules E.S. Teotonio, Hermi F. Brito and Oscar L. Malta

    Journal of Luminescence, ISSN: 00222313, Volume: 193, Pages: 98-105, Published: January 2018 Elsevier B.V.
    Abstract Two novel luminescent europium tris ( β -diketonate) complexes [Eu(dbm) 3 ·PX] and [Eu(acac) 3 ·PX] (dbm: dibenzoylmethane, acac: acetylacetonate and PX: piroxicam) were successfully synthesized. These coordination compounds were characterized by infrared vibrational spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and luminescence spectroscopy. The thermal behavior of the complexes was investigated by thermogravimetric analysis (TG) and differential thermogravimetric analysis (DTG) techniques. The optical results have shown that these complexes present a clear intra and inter-molecular energy transfer and corroborates the sensitivity of their emission efficiency to the excitation wavelength, multiphonon non-radiative decays and temperature dependence. These new complexes may act as efficient light converting molecular devices, suggesting that they can be used for controllable photonic applications.

  • Red-emitting magnetic nanocomposites assembled from ag-decorated Fe3O4@sio2 and Y2O3:Eu3+: Impact of iron-oxide/silver nanoparticles on Eu3+ emission
    Latif U. Khan, Luis F. M. Zambon, Jacinete L. Santos, Rodrigo V. Rodrigues, Luelc S. Costa, Diego Muraca, Kleber R. Pirota, Maria C. F. C. Felinto, Oscar L. Malta and Hermi F. Brito

    ChemistrySelect, eISSN: 23656549, Pages: 1157-1167, Published: January 2018 Wiley

  • Rare earth-indomethacinate complexes with heterocyclic ligands: Synthesis and photoluminescence properties
    João Batista M. Resende Filho, Paulo R. Santos, Juliana A. Vale, Wagner M. Faustino, Danyelle S. Farias, Hermi F. Brito, Maria C. F. C. Felinto and Ercules E. S. Teotonio

    Journal of the Brazilian Chemical Society, ISSN: 01035053, eISSN: 16784790, Pages: 2281-2290, Published: December 2017 Sociedade Brasileira de Quimica
    In this work, synthesis, characterization and photophysical properties of trivalent rare earth complexes with a nonsteroidal anti-inflammatory drug [the indomethacinate (indo), presenting formulas RE(indo)3(H2O)x (x = 3, for Eu and Gd, and x = 4 for Tb), RE(indo)3(bipy) and RE(indo)3(phen) (bipy: 2,2’-bipyridine, and phen: 1,10-phenanthroline)] were investigated. Based on photoluminescent results, the intramolecular energy transfer process from T1 triplet states of indo, phen and bipy ligands to the D0 emitting level of the Eu ion in the coordination compounds is discussed. Accordingly, it is proposed two possible intramolecular energy transfer mechanisms between indomethacinate ligand and rare earth ions, which involve the participation of excited electronic states of the heterocyclic ligands as intermediate ones.

  • Photoluminescence of single-phased white light emission materials based on simultaneous Tb3+, Eu3+and Dy3+doping in CaWO4matrix
    Helliomar P. Barbosa, Ivan G.N. Silva, Maria Claudia F.C. Felinto, Ercules E.S. Teotonio, Oscar L. Malta and Hermi F. Brito

    Journal of Alloys and Compounds, ISSN: 09258388, Volume: 696, Pages: 820-827, Published: 2017 Elsevier Ltd
    Abstract The triply-doped xTb 3+ /xEu 3+ /xDy 3+ CaWO 4 (x: 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 mol%) nanomaterials were prepared at room temperature by a coprecipitation method. The luminescence materials were characterized by X-ray powder diffraction (XPD), thermal analysis (TG), infrared absorption spectroscopy (FTIR) and UV excited photoluminescence. The prepared powder phosphors are single-phase scheelite structure with porous morphology and particle sizes around 11 nm. The materials display white color from cool to the warm white, under UV excitation, as a result of the intraconfigurational 4f transitions from trivalent rare earth ions. The non-radiative energy transfer processes from the O→W and O→Eu LMCT as well as the 4f 8 →4f 7 5d 1 states to the intraconfigurational 4f excited levels of rare earth ions and simultaneous emissions from the 4 F 9/2 (Dy 3+ )→ 5 D 4 (Tb 3+ )→ 5 D 1 , 5 D 0 (Eu 3+ ) emitter levels are reported. Furthermore, CIE parameters and the color correlated temperature (CCT) are discussed in order to characterize the color emission. Based on the results, these luminescence materials may be potential candidates for white light emitting diodes and solid-state lighting.

  • Efficient multicolor tunability of ultrasmall ternary-doped LaF3 nanoparticles: Energy conversion and magnetic behavior
    Navadeep Shrivastava, Khan, Vargas, Carlos Ospina, Coaquira, Giorgio Zoppellaro, Brito, Yasir Javed, Shukla, Felinto and Surender K. Sharma

    Physical Chemistry Chemical Physics, ISSN: 14639076, Pages: 18660-18670, Published: 2017 Royal Society of Chemistry
    Visible color tunability in ultrasmall LaF3:xCe3+,xGd3+,yEu3+ (x = 5; y = 1, 5, 10, and 15 mol%) NPs depending on the ratio Eu2+/Eu3+.

  • Building block magneto-luminescent nanomaterials of iron-oxide/ZnS@LaF3:Ce3+,Gd3+,Tb3+ with green emission
    Navadeep Shrivastava, Khan, Khan, Vargas, Moscoso-Londoño, Carlos Ospina, Brito, Yasir Javed, Felinto, Menezes, Marcelo Knobel and Sharma

    Journal of Materials Chemistry C, ISSN: 20507534, eISSN: 20507526, Pages: 2282-2290, Published: 2017 Royal Society of Chemistry
    The bifunctional nanocomposite showing strong green emission of Tb3+ ions under a UV lamp (λ = 254 nm), with and without external magnetic field.

  • Endophytic bacteria and rare earth elements; promising candidates for nutrient use efficiency in plants
    Katia R. Prieto, Francisco Echaide-Aquino, Aurora Huerta-Robles, Hellen P. Valério, Gloria Macedo-Raygoza, Fernanda M. Prado, Marisa H.G. Medeiros, Hermi F. Brito, Ivan G.N. da Silva, Maria C.F. Cunha Felinto, James F. White, Paolo Di Mascio and Miguel J. Beltran-García

    Plant Macronutrient Use Efficiency: Molecular and Genomic Perspectives in Crop Plants, Pages: 285-306, Published: 1 January 2017 Elsevier Inc.
    Abstract Nutrient use efficiency (NUE) depends on the plant’s ability to take up nutrients efficiently from the soil, but also depends on internal transport, storage and remobilization of nutrients. Nitrogen (N) is a fundamental element regulating plant growth and development. Plants have evolved inorganic and organic N-uptake systems to cope with heterogeneous N availability in the soil. However, NUE is dependent on root growth and root architecture. Endophytic bacteria have a direct influence on root growth and increase nutrient uptake. Under reciprocal exchange, trading carbon for nutrients, plant and bacteria establish a symbiotic association. In this chapter we will address how endophytic bacteria might contribute to efficient nutrient uptake, especially organic nitrogen, through bacterial cell degradation or by externally activating nitrogen transporters. Also, here we propose the use of rare earth elements as an option for improving NUE in plants and their possible use as fertilizers.

  • Optical and magnetic nanocomposites containing Fe3O4@SiO2 grafted with Eu3+ and Tb3+ complexes
    Khan, Muraca, Brito, Moscoso-Londoño, Felinto, Pirota, Teotonio and Malta

    Journal of Alloys and Compounds, ISSN: 09258388, Volume: 686, Pages: 453-466, Published: 25 November 2016 Elsevier Ltd
    Abstract The fabrication of bifunctional nanocomposites, co-assembling photonic (RE3+) and magnetic (Fe3O4) features into single entity nanostructures is reported through a facile method, using Fe3O4 as core nanoparticles, which were coated with SiO2 shell and further grafted with Eu3+ and Tb3+ complexes. The sophisticated structural features and morphologies of the core-shell Fe3O4@SiO2-(TTA-RE-L) nanomaterials were studied by Small-angle X-ray Scattering. The core mean size 〈 D SAXS 〉 , shell thickness Δ R , cluster size ξ and fractal dimension DF were determined by fitting the experimental SAXS data, corroborating through Transmission Electron Microscopy images. The DC magnetic properties at temperatures of 2 and 300 K were explored in support to the structural conclusions from SAXS and TEM analyses. The magnetic contributions of the RE3+ ions to the magnetizations of the Eu3+ and Tb3+ nanocomposites were discussed. The photoluminescence properties of the Eu3+ and Tb3+ nanocomposites based on the emission spectral data and luminescence decay curves were studied. The experimental intensity parameters (Ωλ), lifetimes (τ), emission quantum efficiencies (η) as well as radiative (Arad) and non-radiative (Anrad) decay rates were calculated and discussed, in addition, the structural conclusions from the values of the 4f-4f intensity parameters in the case of the Eu3+ ion. These novel Eu3+ and Tb3+ nanocomposites may act as red and green emitting layers for magnetic and light converting molecular devices.

  • Highly-sensitive Eu3+ ratiometric thermometers based on excited state absorption with predictable calibration
    Adelmo S. Souza, Luiz A. O. Nunes, Ivan G. N. Silva, Fernando A. M. Oliveira, Leonis L. Da Luz, Hermi F. Brito, Maria C. F. C. Felinto, Rute A. S. Ferreira, Severino A. Júnior, Luís D. Carlos and Oscar L. Malta

    Nanoscale, ISSN: 20403364, eISSN: 20403372, Pages: 5327-5333, Published: 7 March 2016 Royal Society of Chemistry
    Thermally excited state absorption in Eu3+ is used to propose a new ratiometric luminescent thermometer with a predicted calibration factor.

  • Valence control of Pr in ZrO2 nanocrystals by aliovalent Gd3+ co-doping
    José M. Carvalho, Mika Lastusaari, Lucas C.V. Rodrigues, Jorma Hölsä, Maria C.F.C. Felinto and Hermi F. Brito

    Journal of Luminescence, ISSN: 00222313, Volume: 170, Pages: 627-632, Published: 1 February 2016 Elsevier
    Abstract Praseodymium doped ZrO 2 materials were prepared via sol–gel route and structurally characterized by X ray powder diffraction (XPD) technique as well as Rietveld refinements. The addition of the Gd 3+ co-dopant gradually changes the zirconia structure from monoclinic to tetragonal, and then to cubic. Intensification of the Pr 3+ luminescence was observed with the increasing Gd 3+ co-dopant concentration. Emission spectra of the Zr 0.99− x Gd x Pr 0.01 O 2 materials show an initial strengthening of the red emission of Pr 3+ ( 1 D 2 → 3 H 4 transition) with increasing Gd 3+ co-doping. However, the luminescence is quenched at the highest Gd 3+ concentration-possibly due to strongly increased concentration of the charge compensation defects. The valence change (Pr IV →Pr 3+ ) is supported by the XANES results on the L III edge of Pr. Although predominantly in the Pr 3+ form irrespective of the Gd 3+ concentration, the contribution from Pr IV is clearly visible at low (or zero) Gd 3+ concentrations leading to the loss of Pr 3+ and to poor luminescence output. Though enhancing the emission intensity of Pr 3+ , the defect clusters engender short Pr 3+ –Pr 3+ distances enhancing the cross-relaxation process coupling the 3 P 0 → 1 D 2 relaxation with the 3 H 4 → 3 H 6 excitation. This process leads to the high red/blue–green emission ratio by quenching the 3 P 0 → 3 H 4 transition in blue–green. Eventually, the increased Gd 3+ co-doping dilutes the Pr 3+ ions and, the cross-relaxation process becomes non-operational; the quenching of the 3 P 0 → 3 H 4 transition is reversed.

  • Highly luminescent Eu3+-doped benzenetricarboxylate based materials
    Ivan G.N. Silva, Danilo Mustafa, Bruno Andreoli, Maria C.F.C. Felinto, Oscar L. Malta and Hermi F. Brito

    Journal of Luminescence, ISSN: 00222313, Volume: 170, Pages: 364-368, Published: 1 February 2016 Elsevier
    Abstract [RE(TMA)] anhydrous complexes (RE 3+ : Y, Gd and Lu) present high red emission intensity with a quantum efficiency (~45%) for the [Y(TMA):Eu 3+ ] complexes, due to the absence of non-radioactive decay pathways mediated by water molecules. The complexes were prepared in mild conditions. All the compounds are crystalline and thermostable up to 460 °C. Phosphorescence data of the complexes with Y, Gd and Lu show that the T 1 state of the TMA 3− anion has energy higher than the 5 D 0 emitting level of the Eu 3+ ion, indicating that the ligand can act as an intramolecular energy sensitizer. The photoluminescence properties of the doped materials were studied based on the excitation and emission spectra and luminescence decay curves. The experimental intensity parameters ( Ω λ ), lifetimes ( τ ), radiative ( A rad ) and non-radiative ( A nrad ) decay rates were determined and discussed.

  • Luminescence investigation of R3+-doped alkaline earth tungstates prepared by a soft chemistry method
    Helliomar P. Barbosa, Jiang Kai, Ivan G.N. Silva, Lucas C.V. Rodrigues, Maria C.F.C. Felinto, Jorma Hölsä, Oscar L. Malta and Hermi F. Brito

    Journal of Luminescence, ISSN: 00222313, Volume: 170, Pages: 736-742, Published: 1 February 2016 Elsevier
    Abstract Highly luminescent rare earth (R 3+ ) doped alkaline-earth tungstates MWO 4 :R 3+ (M 2+ : Ca, Sr and Ba, R 3+ : Eu, Tb, Gd) were prepared with a room temperature coprecipitation method. The phosphors were characterized by X-ray powder diffraction (XPD), thermal analysis (TG), infrared absorption spectroscopy (FTIR) and UV excited photoluminescence. The as-prepared MWO 4 :R 3+ particles belong to the tetragonal scheelite phase, and are well crystallized and are of the average size of 16–48 nm. The excitation and emission spectra of the materials were recorded at 300 and 77 K temperatures. The luminescent materials exhibit intense red (Eu 3+ ) and green (Tb 3+ ) colors under UV excitation. The excitation spectra of the Eu 3+ doped materials show broad bands arising from the ligand-to-metal charge transfer transitions (O 2 − →W VI and O 2− →Eu 3+ ) as well as narrow bands from 4f–4f intraconfigurational transitions of Eu 3+ . 4f–4f emission data of the Eu 3+ and Tb 3+ in the MWO 4 host matrices as well as the values of emission quantum efficiencies of the 5 D 0 level and the 4f–4f experimental intensity parameters of Eu 3+ ion are presented and discussed.

  • Luminescent hybrid materials functionalized with lanthanide ethylenodiaminotetraacetate complexes containing β-diketonate as antenna ligands
    Franklin P. Aguiar, Israel F. Costa, José Geraldo P. Espínola, Wagner M. Faustino, Jandeilson L. Moura, Hermi F. Brito, Tiago B. Paolini, Maria Cláudia F.C. Felinto and Ercules E.S. Teotonio

    Journal of Luminescence, ISSN: 00222313, Volume: 170, Pages: 538-546, Published: 1 February 2016 Elsevier B.V.
    Abstract Three organic–inorganic hybrid materials based on silica gel functionalized with (3-aminopropyl)trimethoxysilane (APTS), [3-(2-aminoetilamino)-propil]-trimetoxissilano (DAPTS) and 3-[2-(2-aminoetilamino)etilamino] propiltrimetoxysilane (TAPTS) and subsequently modified with EDTA derivative were prepared by nonhomogeneous route and were then characterized. The resulting materials named SilXN-EDTA ( X =1 for APTS, 2 for DAPTS and 3 for TAPTS) were used to obtain new lanthanide Ln 3+ -β-diketonate (Ln 3+ =Eu 3+ , Gd 3+ and Tb 3+ ) complexes covalently linked to the functionalized silica gel surfaces (named SilXN-EDTALn-dik, dik=tta, dbm, bzac and acac). The photophysical properties of the new luminescent materials were investigated and compared with those with similar system presenting water molecules coordinated to the lanthanide ions, SilXN-EDTALn-H 2 O. The SilXN-EDTAEu-dik and SilXN-EDTATb-dik systems displayed characteristic red and green luminescence when excited by UV radiation. Furthermore, the quantitative results showed that the emission quantum efficiency ( η ), experimental intensity parameters Ω 2 and Ω 4 , and Einstein's emission coefficient ( A 0 J ) of the SilXN-EDTAEu-dik materials were largely dependent on the ligands. Based on the luminescence data, the most efficient intramolecular energy transfer processes were found to the SilXN-EDTAEu-dik (dik: tta and dbm) and SilXN-EDTATb-acac materials, which exhibited more pure emission colors. These materials are promising red and green phosphors, respectively.

  • Mechanoluminescence of coordination compounds
    Ercules Epaminondas Sousa Teotonio, Wagner Mendonça Faustino, Hermi Felinto Brito, Maria Claudia França Cunha Felinto, Jandeilson Lima Moura, Israel Ferreira Costa and Paulo Roberto Silva Santos

    Triboluminescence: Theory, Synthesis, and Application, Pages: 39-63, Published: 1 January 2016 Springer International Publishing
    Mechanoluminescence (ML) involves all luminescence phenomena induced by mechanical action on solids. In this case, a wide varieties of mechanical stimuli, such as compressing, stretching, static loading (pressure-step), pressure pulse, cleaving, rubbing, and grinding, might induce the excitation of solids, yielding luminescence phenomena. The present chapter discusses on mechanoluminescent properties of transition metal and lanthanide coordination compounds. The principal aim of this chapter is to describe the recent facts about the mechanisms of mechanoluminescence and their correlation with structural properties. It will be also presented a concise overview on the latest progress made on the current variety of ML coordination compounds or materials based on transition and lanthanide metals. The recent studies in this area may lead to the development of ML materials for smart optical sensors for real-time damage detections, monitoring civil and military structures, luminescent probes for biological applications, and lightning systems.

  • Low temperature synthesis of luminescent RE2O3: Eu3+ nanomaterials using trimellitic acid precursors
    Ivan G. N. Silva, Danilo Mustaf, Maria C. F. C. Felinto, Wagner M. Faustino, Ercules E. S. Teotonio, Oscar L. Malta and Hermi F. Brito

    Journal of the Brazilian Chemical Society, ISSN: 01035053, eISSN: 16784790, Pages: 2629-2639, Published: 1 December 2015 Sociedade Brasileira de
    [RE(TLA)·(H2O)n:Eu3+] (RE3+: Y, Gd and Lu; TLA: trimellitic acid) precursor complexes were synthesized by an one step aqueous co-precipitation method. After annealing for 1 h, RE2O3:Eu3+ nanophosphors were formed through the benzenetricarboxylate low temperature thermolysis method (500-1000 oC). The compounds were characterized by using different techniques [elemental analysis (CHN), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG/DTG), X-ray powder diffraction (XPD) and scanning electron microscope (SEM)]. The XPD data indicated that the Y2O3:Eu3+ materials have crystallite size range from 11 to 62 nm. The SEM and transmission electron microscopy (TEM) images show that the annealed materials keep morphological similarities with the precursor complexes. The photoluminescence properties were studied based on the excitation and emission spectra, and luminescence decay lifetimes of the 5D0 emitting level of the Eu3+ ion. The experimental intensity parameters (Ωλ), lifetimes (τ), as well as radiative (Arad) and non-radiative (Anrad) decay rates were calculated and discussed. The RE2O3:Eu3+ phosphors (RE: Y3+ and Lu3+) annealed at 500 to 1000 oC have emission quantum efficiency (intrinsic quantum yield) values from 60 to 82%, indicating that this material can be potentially used for optical markers applications.

  • On the quenching of trivalent terbium luminescence by ligand low lying triplet state energy and the role of the 7F5 level: The [Tb(tta)3 (H2O)2] case
    Souza, Nunes, Felinto, Brito and Malta

    Journal of Luminescence, ISSN: 00222313, Volume: 167, Pages: 167-171, Published: 8 July 2015 Elsevier
    Abstract In this work we discuss the observed Tb 3+ ion luminescence quenching, due to the relative ligand low lying triplet state energy, in the [Tb(tta) 3 (H 2 O) 2 ] compound at low and room temperature (tta=thenoyltrifluoroacetonate). Theoretical energy transfer rates, for both multipolar and exchange mechanisms, were calculated and discussed on the basis of selection rules and energy mismatch conditions from the [Tb(tta) 3 (H 2 O) 2 ] emission spectra. We have concluded that the exchange mechanism by far dominates, in the present case, and that the long first excited state 7 F 5 lifetime (in the millisecond scale) plays a crucial role in the Tb 3+ luminescence quenching.

  • The Role of the Ligand-to-Metal Charge-Transfer State in the Dipivaloylmethanate-Lanthanide Intramolecular Energy Transfer Process
    Yolanda C. Miranda, Leide L. A. L. Pereira, José H. P. Barbosa, Hermi F. Brito, Maria C. F. C. Felinto, Oscar L. Malta, Wagner M. Faustino and Ercules E. S. Teotonio

    European Journal of Inorganic Chemistry, ISSN: 14341948, eISSN: 10990682, Volume: 2015, Pages: 3019-3027, Published: 1 June 2015 Wiley-VCH
    Two new bis(dipivaloylmethanate)nitrato-bis(triphenylphosphine oxide)lanthanide(III) complexes [Eu(dpm)2(NO3)(tppo)2] (1) and [Tb(dpm)2(NO3)(tppo)2] have been prepared in monomeric form. The structural behavior of these coordination compounds is significantly different from those of [Eu2(dpm)6] and [Tb2(dpm)6] dimeric complexes. The photoluminescent properties of the monomeric and dimeric complexes are dependent on the energy positions of the low-lying ligand-to-metal charge-transfer (LMCT) state, which may be correlated with the chelating and chelate bridging coordination modes of the dpm ligand, respectively. The monomeric complex presents higher luminescence intensity than the dimeric complex due to the higher energy of the LMCT state in this system. Although the excited energy levels of the EuIII ion in complex 1 undergo efficient depopulation by LMCT, the same is not observed for the 5D0 emitting level, which presents values of the emitting lifetime that are almost temperature independent. The triboluminescence phenomenon of the [Ln(dpm)2(NO3)(tppo)2] complex is also discussed.

  • Low temperature synthesis and optical properties of the R2O3:Eu3+ nanophosphors (R3+: Y, Gd and Lu) using TMA complexes as precursors
    Silva, Rodrigues, Souza, Kai, Felinto, Hölsä, Brito and Malta

    Optical Materials, ISSN: 09253467, Pages: 41-48, Published: 1 February 2015 Elsevier B.V.
    Abstract The R 2 O 3 :Eu 3+ (R 3+ : Y, Gd and Lu) nanophosphors were synthesized with a low temperature thermolysis method using rare earth 1,3,5-benzenetricarboxylate (TMA) complexes as precursors. The R(TMA):Eu 3+ (1 mole %) complexes were synthesized using the co-precipitation method which complexes were then annealed at temperatures from 500 to 1000 °C for 1 h, yielding the cubic C-type R 2 O 3 :Eu 3+ materials. The XPD patterns revealed no impurities in C-R 2 O 3 obtained at any temperature. The Scherrer’s equation based on powder diffraction data confirmed an increase in crystallite size from 6 to 52 nm with increasing annealing temperature from 500 to 1000 °C for Y 2 O 3 , respectively, agreeing with the SEM and TEM data. Similar results were obtained for the other R 2 O 3 :Eu 3+ . The excitation spectra show a broad oxide to europium charge transfer absorption band at 260 nm, i.e. O 2− (2p) → Eu 3+ (4f 6 ) LMCT, as well as the narrow lines assigned to the 4f–4f transitions of the Eu 3+ ion. The characterization of the photoluminescence properties of the phosphors was also based on the analysis of the emission spectra and luminescence decay curves. The experimental intensity parameters ( Ω λ ), lifetimes ( τ ), as well as radiative ( A rad ) and non-radiative ( A nrad ) decay rates were calculated and discussed.

  • Red-green emitting and superparamagnetic nanomarkers containing Fe3O4 functionalized with calixarene and rare earth complexes
    Latif U. Khan, Hermi F. Brito, Jorma Hölsä, Kleber R. Pirota, Diego Muraca, Maria C.F.C. Felinto, Ercules E.S. Teotonio and Oscar L. Malta

    Inorganic Chemistry, ISSN: 00201669, eISSN: 1520510X, Pages: 12902-12910, Published: 15 December 2014 American Chemical
    The design of bifunctional magnetic luminescent nanomaterials containing Fe3O4 functionalized with rare earth ion complexes of calixarene and β-diketonate ligands is reported. Their preparation is accessible through a facile one-pot method. These novel Fe3O4@calix-Eu(TTA) (TTA = thenoyltrifluoroacetonate) and Fe3O4@calix-Tb(ACAC) (ACAC = acetylacetonate) magnetic luminescent nanomaterials show interesting superparamagnetic and photonic properties. The magnetic properties (M-H and ZFC/FC measurements) at temperatures of 5 and 300 K were explored to investigate the extent of coating and the crystallinity effect on the saturation magnetization values and blocking temperatures. Even though magnetite is a strong luminescence quencher, the coating of the Fe3O4 nanoparticles with synthetically functionalized rare earth complexes has overcome this difficulty. The intramolecular energy transfer from the T1 excited triplet states of TTA and ACAC ligands to the emitting levels of Eu(3+) and Tb(3+) in the nanomaterials and emission efficiencies are presented and discussed, as well as the structural conclusions from the values of the 4f-4f intensity parameters in the case of the Eu(3+) ion. These novel nanomaterials may act as the emitting layer for the red and green light for magnetic light-converting molecular devices (MLCMDs).

  • Structure–property relationship of luminescent zirconia nanomaterials obtained by sol–gel method
    José M. Carvalho, Lucas C. V. Rodrigues, Maria C. F. C. Felinto, Luiz A. O. Nunes, Jorma Hölsä and Hermi F. Brito

    Journal of Materials Science, ISSN: 00222461, eISSN: 15734803, Pages: 873-881, Published: 22 November 2014 Kluwer Academic
    Nanocrystalline ZrO2 materials were prepared by sol–gel method combining different W = [H2O]/[ZTB] ratios (ZTB: zirconium tetrabutoxide) with 600, 800, and 1000 °C annealing temperatures, yielding diverse phase compositions. A lower post-synthesis annealing temperature (600 °C) favored the t-ZrO2 tetragonal phase while higher temperatures (800 and 1000 °C) yielded the monoclinic one (m-ZrO2). Depending on the preparation conditions, mixed structure materials are readily obtained. The luminescence activator in the undoped ZrO2 is assumed as trivalent titanium and emission bands are assigned to the 3d1(eg) → 3d1(t2g) transition. Due to weaker crystal field in m-ZrO2 form, the Ti3+ emission band is red-shifted from 410 nm in t-ZrO2 to 500 nm. The luminescence intensity of the t-ZrO2 form is quenched at higher temperature than that of m-ZrO2, indicating higher activation energy and smaller Stokes shift. The undoped ZrO2 excitation seems to involve photoionization of Ti3+ to TiIV. Simultaneously, the freed electron is trapped to the oxygen vacancies (F++ centers) created by Ti3+/TiIV charge compensation, so this can be considered as a metal-to-host/ligand charge transfer. Since most of the excitation results in immediate emission, the traps are probably very shallow though deeper ones leads to the persistent luminescence from the undoped ZrO2.

  • Novel luminescent Eu3+-indandionate complexes containing heterobiaryl ligands
    João B. M. Resende Filho, Jannine C. Silva, Juliana A. Vale, Hermi F. Brito, Wagner M. Faustino, José G. P. Espínola, Maria C. F. C. Felinto and Ercules E. S. Teotonio

    Journal of the Brazilian Chemical Society, ISSN: 01035053, eISSN: 16784790, Pages: 2080-2087, Published: 1 November 2014 Sociedade Brasileira de
    Novel Ln3+-indandionate complexes of formulas [Ln(aind)3L(H2O)] and [Ln(bind)3L]∙H2O (L: 1,10-phenanthroline (phen) or 4,7-dimethyl-1,10-phenanthroline (dmphen), Ln3+: Eu3+ or Gd3+, aind: 2-acetyl-1,3-indandionate and bind: 2-benzoyl-1,3-indandionate) were synthesized and characterized by elemental analysis, infrared spectroscopy, and thermogravimetric analyses. The characterization data are consistent with the presence of a water lattice molecule in the [Ln(bind)3L]∙H2O compounds. However, the data also suggest that the water acts as a coordinated molecule in the [Ln(aind)3L(H2O)] ones. Theoretical geometries of the Eu3+-complexes have been optimized via the SPARKLE/AM1 Model for lanthanide complexes that are consistent with their luminescence experimental data. The photoluminescence properties of the Eu3+-compounds have been discussed in terms of experimental intensity parameters (Ω2 and Ω4), radiative (Arad), and non-radiative (Anrad) spontaneous emission coefficients. The higher values of emission quantum efficiency (η) of the [Eu(bind)3L]∙H2O compounds reflect the absence of luminescence-quenching water molecule in their first coordination spheres.

  • Co-dopant influence on the persistent luminescence of BaAl 2O4:Eu2+,R3+
    Lucas C.V. Rodrigues, Jorma Hölsä, José M. Carvalho, Cássio C.S. Pedroso, Mika Lastusaari, Maria C.F.C. Felinto, Shigeo Watanabe and Hermi F. Brito

    Physica B: Condensed Matter, ISSN: 09214526, Volume: 439, Pages: 67-71, Published: 15 April 2014 Elsevier BV
    The R3+ (rare earth) co-dopants may have a surprisingly important role in persistent luminescence – enhancement of up to 1–3 orders of magnitude may be obtained in the performance of these phosphor materials – depending strongly on the R3+ ion, of course. In this work, the effects of the R3+ co-dopants in the BaAl2O4:Eu2+,R3+ materials were studied using mainly thermoluminescence (TL) and synchrotron radiation XANES methods. In BaAl2O4, the conventional and persistent luminescence both arise from the 4f7→4f65d1 transition of Eu2+, yielding blue–green emission color. The former, in the presence of humidity, turns to more bluish because of creation of an additional Eu2+ luminescence centre which is not, however, visible in persistent luminescence. The trap structure in the non-co-doped BaAl2O4:Eu2+ is rather complex with 4–5 TL bands above room temperature. With R3+ co-doping, this basic structure is modified though no drastic change can be observed. This underlines the fact that even very small changes in the trap depths can produce significant modifications in the persistent luminescence efficiency. It should be remembered that basically the persistent luminescence performance is controlled by the Boltzmann population law depending exponentially on both the temperature and trap depth. Some mechanisms for persistent luminescence have suggested the presence of either divalent R2+ or tetravalent RIV during the charging of the Eu2+ doped materials. The present XANES measurements on BaAl2O4:Eu2+,R3+ confirmed the presence of only the trivalent form of the R3+ co-dopants excluding both of these pathways. It must thus be concluded, that the energy is stored in intrinsic and extrinsic defects created by the synthesis conditions and charge compensation due to R3+ co-doping. Even though the effect of the R3+ co-dopants was carefully exploited and characterized, the differences in the effect of different R3+ ions with very similar chemical and spectroscopic properties could not be explained in a satisfactory manner. More work is – and perhaps a completely new approach may be – needed.

  • Defect to R3+ energy transfer: Colour tuning of persistent luminescence in CdSiO3
    Lucas C. V. Rodrigues, Jorma Hölsä, Mika Lastusaari, Maria C. F. C. Felinto and Hermi F. Brito

    Journal of Materials Chemistry C, ISSN: 20507534, eISSN: 20507526, Pages: 1612-1618, Published: 7 March 2014 Royal Society of Chemistry (RSC)

  • Red (Eu3+), green (Tb3+) and ultraviolet (Gd 3+) emitting nitrilotriacetate complexes prepared by one-step synthesis
    Ivan G.N. Silva, Hermi F. Brito, Ernesto R. Souza, Danilo Mustafa, Maria C.F.C. Felinto, Luis D. Carlos and Oscar L. Malta

    Zeitschrift fur Naturforschung - Section B Journal of Chemical Sciences, ISSN: 09320776, Pages: 231-238, Published: February 2014 Verlag der Zeitschrift fur
    The [RE(NTA)(H2O)2]⋅(H2O) rare-earth complexes (RE3+: Eu, Gd, Tb and NTA: nitrilotriacetate) were synthesized and characterized by elemental analysis, thermogravimetry, X-ray diffraction, and infrared spectroscopy. The complexes show high crystallinity and thermostability. The photoluminescence behavior was studied based on the excitation and emission spectra, and luminescence decay curves. The compounds exhibit red (Eu3+), green (Tb3+) and UV (Gd3+) monochromatic emissions under UV excitation. The NTA ligand acts as luminescence sensitizer in the ligand-to- RE3+ intramolecular energy transfer process, owing to the fact that the first excited triplet state (T1: 29 000 cm−1) is located above of the 5D0 (Eu3+) and 5D4 (Tb3+) emitting levels. The experimental intensity parameters Ωλ (λ: 2 and 4) for the Eu3+ NTA complex were calculated, and the results are discussed. The Gd3+-NTA complex exhibits a high-intensity emission band in the UV region (32 000 cm−1) assigned to the 6P7/2→8S7/2 intraconfigurational transition.

  • Persistent luminescence of cadmium silicates
    Lucas C. V. Rodrigues, Mika Lastusaari, Hermi F. Brito, Maria C. F. C. Felinto, José M. Carvalho, Jorma Hölsä and Oscar L. Malta

    Physica Scripta, ISSN: 00318949, eISSN: 14024896, Published: April 2014 Institute of Physics
    The effect of the band gap on the persistent luminescence of cadmium meta- and orthosilicates was studied with VUV–UV–vis photoluminescence and x-ray absorption spectroscopies (XANES and EXAFS). The narrower band gap of Cd2SiO4 is favourable for persistent luminescence from Pr3+ but not from Tb3+ due to the trivalent rare-earth energy level positions in the band gap.

  • Photoluminescent PMMA polymer films doped with Eu3+-β-diketonate crown ether complex
    Edison B. Gibelli, Jiang Kai, Ercules E.S. Teotonio, Oscar L. Malta, Maria C.F.C. Felinto and Hermi F. Brito

    Journal of Photochemistry and Photobiology A: Chemistry, ISSN: 10106030, Volume: 251, Pages: 154-159, Published: 19 August 2013 Elsevier B.V.
    Abstract In this work it is reported the photoluminescence sensitization effect of the bis(dibenzo-18-crown-6)diaquatris(thenoyltrifluoroacetonate)europium(III) compound, [Eu(tta) 3 (DB18C6) 2 (H 2 O) 2 ], doped into a blend of poly(methylmethacrylate) (PMMA) and polyethylene glycol (PEG) in film form. The TGA results indicate that the Eu 3+ -complex precursor is immobilized in the polymer matrix by the interaction between the Eu 3+ complex and the oxygen atoms of the PMMA polymer. The thermal behavior of these luminescent systems is similar to that of the undoped polymer. The emission spectra of the Eu 3+ -complex in the PMMA/PEG blends recorded at room temperature exhibit the characteristic bands arising from the 5 D 0  →  7 F J ( J  = 0–4) intraconfigurational transitions. The emission quantum efficiency of the Eu 3+ ion doped films increased significantly, indicating an effective interaction between the Eu 3+ -complex and the polymer matrix, and both the substitution of water molecules in the first coordination sphere and an efficient luminescence co-sensitization of the Eu 3+ luminescent centers.

  • Luminescent material based on the [Eu(TTA)3(H2O) 2] complex incorporated into modified silica particles for biological applications
    Ana Valéria S. Lourenço, Cláudia A. Kodaira, Eduardo M. Ramos-Sanchez, Maria Cláudia F.C. Felinto, Hiro Goto, Magnus Gidlund, Oscar L. Malta and Hermi F. Brito

    Journal of Inorganic Biochemistry, ISSN: 01620134, eISSN: 18733344, Volume: 123, Pages: 11-17, Published: June 2013 Elsevier BV
    Amino-functionalized luminescent silica particles were investigated for use in immunoassays. The particles were prepared by the Stöber method where the [Eu(TTA)3(H2O)2] complex (TTA: 3-thenoyltrifluoroacetonate) was incorporated into silica particles during the hydrolysis and condensation of TEOS: tetraethylorthosilicate. Then, the amino groups were introduced in the particle surface using APTS: 3-aminopropyltriethoxisilane. The resulting particles were characterized by scanning electron microscopy (SEM), X ray diffraction (XRD) and photoluminescence spectroscopy. In order to demonstrate the viability of the use of luminescent particles as optical markers, an enzyme-substrate reaction was performed using HRP: horseradish peroxidase. It was possible to verify the binding of HRP-oxidized LDL (low density lipoprotein) and anti-oxLDL antibody-luminescent silica particles through the evaluation of the presence of HRP. The bioassay data open a broad field for the development of protein-tagged luminescent particles for use in biomedical sciences.

  • Spectroscopic properties and quantum cutting in Tb3+-Yb 3+ co-doped ZrO2 nanocrystals
    Terra, Borrero-González, Carvalho, Terrile, Felinto, Brito and Nunes

    Journal of Applied Physics, ISSN: 00218979, Volume: 113, Published: 21 February 2013 AIP Publishing
    Ultraviolet-visible to near-infrared quantum cutting (QC) materials are a promising tool to enhance the efficiency of conventional crystalline silicon solar cells. The spectroscopic properties of Tb3+–Yb3+ co-doped ZrO2 nanocrystals are presented, and the QC mechanisms in these nanocrystals are investigated. The materials were fabricated using the sol gel method and characterized using X-ray powder diffraction, X-ray absorption near edge structure, and luminescence spectroscopy. The incorporation of Yb3+ ions into the host induced a crystalline phase change of ZrO2 from monoclinic to tetragonal to cubic symmetry and influenced the Tb valence state. The Tb3+ visible emission, excitation intensity (monitored by the Tb3+:5D4 emission), decay time of the Tb3+:5D4 emitter level, and down-conversion (DC) emission intensity increased with Yb3+ concentration. Furthermore, a sublinear dependence of the DC intensity on the excitation power at the Tb3+:5D4 level indicated the coexistence of two different QC mechanis...

  • Measurement and model calculation of the temperature dependence of ligand-to-metal energy transfer rates in lanthanide complexes
    Wagner M. Faustino, Luiz A. Nunes, Idelma A.A. Terra, Maria Claudia F.C. Felinto, Hermi F. Brito and Oscar L. Malta

    Journal of Luminescence, ISSN: 00222313, Volume: 137, Pages: 269-273, Published: 2013 Elsevier BV
    Abstract Temperature dependent transient curves of excited levels of a model Eu 3+ complex have been measured for the first time. A coincidence between the temperature dependent rise time of the 5 D 0 emitting level and decay time of the 5 D 1 excited level in the [Eu(tta) 3 (H 2 O) 2 ] complex has been found, which unambiguously proves the T 1 → 5 D 1 → 5 D 0 sensitization pathway. A theoretical approach for the temperature dependent energy transfer rates has been successfully applied to the rationalization of the experimental data.

  • White emission phosphors based on Dy3+-doped into anhydrous rare-earth benzenetricarboxylate complexes
    Ivan G.N. Silva, Jiang Kai, Maria C.F.C. Felinto and Hermi F. Brito

    Optical Materials, ISSN: 09253467, Pages: 978-982, Published: March 2013 Elsevier B.V.
    Abstract White light emitting rare earth anhydrous complexes RE(TMA):Dy3+ (RE3+ = Y3+ and Lu3+) containing the trimesic acid ligands (TMA) were synthesized and characterized by elemental analysis, X-ray diffraction patterns, thermogravimetric analysis and infrared spectroscopy. The crystallinity and thermostability of these luminescent materials were determined. Since the first excited triplet state (T1: 24,000 cm−1) of TMA ligand is located at higher energy than the main emitting 4F9/2 level (21,000 cm−1) of the Dy3+ ion, TMA can act as efficient luminescent sensitizer in the intramolecular energy transfer of RE(TMA):Dy3+ material. The near-white emission colour originated from the intraconfigurational transitions of Dy3+ ion 4F9/2→6HJ is discussed.

  • Defects and charge compensation in CdSiO3: A DFT and synchrotron study
    Hermi F. Brito, Maria C.F.C. Felinto, Jorma Hölsä, Taneli Laamanen, Mika Lastusaari, Pavel Novák, Luiz A.O. Nunes and Lucas C.V. Rodrigues

    Physics Procedia, ISSN: 18753884, eISSN: 18753892, Pages: 1-9, Published: 2013 Elsevier B.V.
    The charge compensation effects induced by aliovalent doping were studied in the monoclinic CdSiO3. An interstitial oxide ion may be feasible in this host to provide the extra negative charge required by the R 3+ doping. The oxide was studied in CdSiO3 using density functional theory (DFT) calculations and synchrotron radiation (SR) luminescence spectroscopy. The crystal structure of this host was significantly modified by the interstitial oxide. The experimental band gap energy (Eg) was perfectly reproduced by the calculations and intrinsic electron traps were revealed. Defect levels were found also in the interstitial oxide containing host, however their role has to be studied further. © 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of [Tomas Wagner]

  • Energy transfer processes in Tb(III)-dibenzoylmethanate complexes with phosphine oxide ligands
    Francisco A. Silva Jr., Helenise A. Nascimento, Dariston K.S. Pereira, Ercules E.S. Teotonio, Hermi F. Brito, Maria Cláudia F.C. Felinto, José Geraldo P. Espínola, Gilberto F. Sá and Wagner M. Faustino

    Journal of the Brazilian Chemical Society, ISSN: 01035053, eISSN: 16784790, Pages: 601-608, Published: 2013 Sociedade Brasileira de Quimica (SBQ)
    The Tb3+-β-diketonate complexes [Tb(DBM)3L], [Tb(DBM)2(NO3)L2] and [Tb(DBM)(NO3)2(HMPA)2] (DBM = dibenzoylmethanate; L: TPPO = triphenylphosphine oxide or HMPA = hexamethylphosphine oxide) were prepared and characterized by elemental analysis (CHN), complexometric titration with EDTA and Fourier transform infrared (FTIR) spectroscopy, and the photoluminescence properties evaluated. The triplet state energies of the coordinated DBM ligands were determined using time-resolved phosphorescence spectra of analogous Gd3+ complexes. The results show that the energies increase along with the number of coordinated nitrate anions replacing the DBM ligand in the complexes. The luminescence spectra and emission lifetime measurements revealed that the ligand-to-metal energy transfer efficiency follows the same tendency. Unlike the tris-DBM complexes, bis- and mono-DBM presented high luminescence, and may act as promising candidates for preparation of the emitting layer of light converting molecular devices (LCMDs).

  • Discovery of the persistent luminescence mechanism of CdSiO 3:Tb 3+
    Lucas C.V. Rodrigues, Hermi F. Brito, Jorma Hölsä, Roberval Stefani, Maria C.F.C. Felinto, Mika Lastusaari, Taneli Laamanen and Luiz A.O. Nunes

    Journal of Physical Chemistry C, ISSN: 19327447, eISSN: 19327455, Volume: 116, Pages: 11232-11240, Published: 24 May 2012 American Chemical Society (ACS)
    The persistent luminescence of CdSiO3:Tb3+ was investigated with photoluminescence, thermoluminescence (TL), synchrotron radiation X-ray absorption (XANES and EXAFS) and UV-VUV spectroscopies. Only the typical intraconfigurational 4f8–4f8 transitions of the Tb3+ ion were observed with no traces of band emission in either the conventional UV excited or persistent luminescence spectra. The trap structure from TL with three traps from 0.65 to 0.85 eV is ideal for room-temperature persistent luminescence similar to, e.g., Sr2MgSi2O7:Eu2+,R3+. Despite the rather low band gap energy, 5.28 eV, the persistent luminescence from Tb3+ is produced only under UV irradiation due to the inauspicious position of the 7F6 ground level deep in the band gap of CdSiO3. This confirms the role of electrons as the charge carriers in the mechanism of Tb3+ persistent luminescence. The XANES spectra indicated the presence of only the trivalent Tb3+ species, thus excluding the direct Tb3+ → TbIV oxidation during the charging process...

  • Structure and luminescent investigation of the Ln(III)-β-diketonate complexes containing tertiary amides
    Ercules E.S. Teotonio, Hermi F. Brito, Gilberto F. De Sá, Maria Cláudia F.C. Felinto, Regina Helena A. Santos, Rodolfo Moreno Fuquen, Israel F. Costa, Alan R. Kennedy, Denise Gilmore and Wagner M. Faustino

    Polyhedron, ISSN: 02775387, Pages: 58-67, Published: 11 May 2012 Elsevier BV
    Abstract The synthesis and photoluminescent properties of Ln(III)–thenoyltrifluoroacetonate and dibenzoylmethanate complexes (Ln = Eu(III) and Gd(III) ions) containing tertiary amides such as dimethylacetamide (DMA), dimethylformamide (DMF), and dimethylbenzamide (DMB) as neutral ligands are reported. The Ln complexes were characterized by elemental analysis, complexometric titration with EDTA, and infrared spectroscopy. Single-crystal X-ray structure data of the [Eu(DBM)3·(DMA)] compound indicates that this complex crystallizes in the triclinic system, space group P 1 ¯ with the following cell parameters: a = 10.2580(3) A, b = 10.3843(2) A, c = 22.3517(5) A, α = 78.906(2)°, β = 78.049(2)°, λ = 63.239(2)°, V = 2066.41(9) A3, and Z = 2. The coordination polyhedron for the Eu(III) complex may be described as an approximate C2v distorted monocapped trigonal prism. The optical properties of the Eu(III) complexes were studied based on the intensity parameters and luminescence quantum yield (q). The values of the Ω2 parameter of the Eu–DBM complexes are larger than those for the Eu–TTA complexes, indicating that the Eu(III) ion is in a more polarizable chemical environment in the former case. The geometries of the complexes have been optimized by using the Sparkle Model, and the results have been used to perform theoretical predictions of the ligand-to-metal energy transfer via direct and exchange Coulomb mechanisms.

  • DFT and synchrotron radiation study of Eu2+ doped BaAl2O4
    Hermi F. Brito, Maria C.F.C. Felinto, Jorma Hölsä, Taneli Laamanen, Mika Lastusaari, Marja Malkamäki, Pavel Novák, Lucas C. V. Rodrigues and Roberval Stefan

    Optical Materials Express, eISSN: 21593930, Pages: 420-431, Published: 1 April 2012 The Optical Society
    The structural distortions resulting from the size mismatch between the Eu2+ luminescent centre and the host Ba2+ cation as well as the electronic structure of BaAl2O4:Eu2+(,Dy3+) were studied using density functional theory (DFT) calculations and synchrotron radiation (SR) luminescence spectroscopy. The modified interionic distances as well as differences in the total energies indicate that Eu2+ prefers the smaller of the two possible Ba sites in the BaAl2O4 host. The calculated Eu2+ 4f7 and 4f65d1 ground level energies confirm that the excited electrons can reach easily the conduction band for subsequent trapping. In addition to the green luminescence, a weak blue emission band was observed in BaAl2O4:Eu2+,Dy3+ probably due to the creation of a new Ba2+ site due to the effect of water exposure on the host.

  • Influence of titanium and lutetium on the persistent luminescence of ZrO2
    José M. Carvalho, Lucas C. V. Rodrigues, Jorma Hölsä, Mika Lastusaari, Luiz A. O. Nunes, Maria C. F. C. Felinto, Oscar L. Malta and Hermi F. Brito

    Optical Materials Express, eISSN: 21593930, Pages: 331-340, Published: 1 March 2012 The Optical Society
    Non-doped as well as titanium and lutetium doped zirconia (ZrO2) materials were synthesized via the sol-gel method and structurally characterized with X-ray powder diffraction. The addition of Ti in the zirconia lattice does not change the crystalline structure whilst the Lu doping introduces a small fraction of the tetragonal phase. The UV excitation results in a bright white-blue luminescence at ca. 500 nm for all the materials which emission could be assigned to the Ti3+eg → t2g transition. The persistent luminescence originates from the same Ti3+ center. The thermoluminescence data shows a well-defined though rather similar defect structures for all the zirconia materials. The kinetics of persistent luminescence was probed with the isothermal decay curve analyses which indicated significant retrapping. The short duration of persistent luminescence was attributed to the quasi-continuum distribution of the traps and to the possibility of shallow traps even below the room temperature.

  • Biolabeling with nanoparticles based on Y2O3: Nd 3+ and luminescence detection in the near-infrared
    Cláudia A. Kodaira, Ana Valéria S. Loureno, Maria Cláudia F.C. Felinto, Eduardo M.R. Sanchez, Francisco J.O. Rios, Luiz Antonio O. Nunes, Magnus Gidlund, Oscar L. Malta and Hermi F. Brito

    Journal of Luminescence, ISSN: 00222313, Volume: 131, Pages: 727-731, Published: April 2011 Elsevier BV
    Abstract Neodymium based fluorescence presents several advantages in comparison to conventional rare earth or enzyme–substrate based fluorescence emitting sources (e.g.Tb, HRP) . Based on this fact we have herein explored a Nd-based fluoroimmunoassay. We efficiently detected the presence of an oxidized low-density lipoprotein (oxLDL) in human plasma a well-known marker for cardiovascular diseases, which causes around 30% of deaths worldwide. Conventional fluoroimmunoassay uses time-resolved luminescence techniques, with detection in the visible range, to eliminate the fluorescence background from the biological specimens. By using an immunoassay based on functionalized Y 2 O 3 :Nd 3+ nanoparticles, where the excitation and emission processes in the Nd 3+ ion occur in the near-infrared (NIR) region, we have succeeded in eliminating the interferences from the biological fluorescence background, avoiding the use of time-resolved techniques. This yields higher emission intensity from the Nd 3+ -nanolabels and efficient detection of anti-oxidized low-density lipoproteins (anti-oxLDL) by Y 2 O 3 :Nd 3+ -antibody–antigen conjugation, leading to a novel biolabeling method.

  • Intermolecular energy transfer and photostability of luminescence-tuneable multicolour PMMA films doped with lanthanide-β-diketonate complexes
    Jiang Kai, Maria C.F.C. Felinto, Luiz A.O. Nunes, Oscar L. Malta and Hermi F. Brito

    Journal of Materials Chemistry, ISSN: 09599428, eISSN: 13645501, Pages: 3796-3802, Published: 2011 Royal Society of Chemistry (RSC)

  • Preparation and photoluminescence properties of functionalized silica materials incorporating europium complexes
    Lourenço, Kodaira, Souza, Felinto, Malta and Brito

    Optical Materials, ISSN: 09253467, Pages: 1548-1552, Published: August 2011 Elsevier B.V.
    Abstract In the present work, the surface of the Eu–BTC = [Eu(EMA)(H2O)2], [Eu(TLA)(H2O)4] and [Eu(TMA)(H2O)6] complexes (EMA = 1,2,3-benzenetricarboxylate, TLA = 1,2,4-benzenetricarboxylate and TMA = 1,3,5-benzenetricarboxylate) was modified using 3-aminopropyltriethoxysilane (APTES) by a new microwave assisted method that proved to be simple and efficient. According to our observations, the most efficient luminescence is the material based on APTES incorporating [Eu(TMA)(H2O)6] complexes, denoted as Eu–TMA–Si, shows the highest emission efficiency. Therefore, it is proposed as a promising material for molecular conjugation in clinical diagnosis.

  • Synthesis, characterization and spectroscopic investigation of new tetrakis(acetylacetonato)thulate(III) complexes containing alkaline metals as countercations
    Guedes, Paolini, Felinto, Kai, Nunes, Malta and Brito

    Journal of Luminescence, ISSN: 00222313, Volume: 131, Pages: 99-103, Published: January 2011 Elsevier BV
    In this work a series of tetrakis complexes C[Tm(acac)4], where C + ¼ Li + ,N a + and K + countercations and acac ¼acetylacetonate ligand, were synthesized and characterized for photoluminescence investigation. The relevant aspect is that these complexes are water-free in the first coordination sphere. The emission spectra of the tetrakis Tm 3+ -complexes present narrow bands characteristic of the 1 G4- 3 H6 (479 nm), 1 G 43 F 4 (650 nm) and 1 G 43 H 5 (779 nm) transitions of the Tm 3+ ion, with the blue emission color at

  • Luminescence enhancement of the Tb(III) ion with the thenoyltrifluoroacetonate ligand acting as an efficient sensitizer
    Ercules E.S. Teotonio, Francisco A. Silva Jr., Dariston K.S. Pereira, Lidiaine M. Santo, Hermi F. Brito, Wagner M. Faustino, Maria Cláudia F.C. Felinto, Regina Helena Santos, Rodolfo Moreno-Fuquen, Alan R. Kennedy and Denise Gilmore

    Inorganic Chemistry Communications, ISSN: 13877003, Pages: 1391-1395, Published: December 2010 Elsevier BV
    The synthesis, structural investigation, and photophysical properties of the complex [Tb(TTA)(2)(NO3) (TPPO)(2)] are reported. Unlike the analog tris-diketonate complex [Tb(TTA)(3)(TPPO)(2)], the new complex presents abnormally high luminescence intensity centered on the terbium ion. Our results clearly suggest a higher energy transfer efficiency from the TEA antenna ligand to the Tb(III) ion in the bis-diketonate complex compared with that in the tris-diketonate complex. A mechanism involving the increasing of triplet state energy when one TTA ligand is replaced by the NO3- group in the first coordination sphere is suggested and experimentally investigated to explain the anomalous luminescence properties of the new complex [Tb(TTA)(2)(NO3)(TPPO)(2)].

  • Thermoluminescence and synchrotron radiation studies on the persistent luminescence of BaAl2O4:Eu2,Dy3
    Rodrigues, Stefani, Brito, Felinto, Hls, Lastusaari, Laamanen and Malkamki

    Journal of Solid State Chemistry, ISSN: 00224596, eISSN: 1095726X, Volume: 183, Pages: 2365-2371, Published: October 2010 Elsevier BV
    The persistent luminescence materials, barium aluminates doped with Eu{sup 2+} and Dy{sup 3+} (BaAl{sub 2}O{sub 4}:Eu{sup 2+},Dy{sup 3+}), were prepared with the combustion synthesis at temperatures between 400 and 600 {sup o}C as well as with the solid state reaction at 1500 {sup o}C. The concentrations of Eu{sup 2+}/Dy{sup 3+} (in mol% of the Ba amount) ranged from 0.1/0.1 to 1.0/3.0. The electronic and defect energy level structures were studied with thermoluminescence (TL) and synchrotron radiation (SR) spectroscopies: UV-VUV excitation and emission, as well as with X-ray absorption near-edge structure (XANES) methods. Theoretical calculations using the density functional theory (DFT) were carried out in order to compare with the experimental data. - Graphical abstract: BaAl{sub 2}O{sub 4}:Eu{sup 2+},Dy{sup 3+} phosphors: Thermoluminescence glow curve and synchrotron radiation spectra. Persistent luminescence photographs obtained after ceased UV irradiation.

  • Optical properties of red, green and blue emitting rare earth benzenetricarboxylate compounds
    Ernesto Rezende Souza, Ivan G.N. Silva, Ercules E.S. Teotonio, Maria C.F.C. Felinto and Hermi F. Brito

    Journal of Luminescence, ISSN: 00222313, Volume: 130, Pages: 283-291, Published: February 2010 Elsevier
    Abstract Red, blue and green emitting rare earth compounds (RE 3+ =Eu 3+ , Gd 3+ and Tb 3+ ) containing the benzenetricarboxylate ligands (BTC) [hemimellitic (EMA), trimellitic (TLA) and trimesic (TMA)] were synthesized and characterized by elemental analysis, complexometric titration, X-ray diffraction patterns, thermogravimetric analysis and infrared spectroscopy. The complexes presented the following formula: [RE(EMA)(H 2 O) 2 ], [RE(TLA)(H 2 O) 4 ] and [RE(TMA)(H 2 O) 6 ], except for Tb-TMA compound, which was obtained only as anhydrous. Phosphorescence data of Gd 3+ -(BTC) complexes showed that the triplet states (T) of the BTC 3− anions have energy higher than the main emitting states of the Eu 3+ ( 5 D 0 ) and Tb 3+ ( 5 D 4 ), indicating that BTC ligands can act as intramolecular energy donors for these metal ions. The high values of experimental intensity parameters ( Ω 2 ) of Eu 3+ -(BTC) complexes indicate that the europium ion is in a highly polarizable chemical environment. Based on the luminescence spectra, the energy transfer from the T state of BTC ligands to the excited 5 D 0 and 5 D 4 levels of the Eu 3+ and Tb 3+ ions is discussed. The emission quantum efficiencies ( η ) of the 5 D 0 emitting level of the Eu 3+ ion have been also determined. In the case of the Tb 3+ ion, the photoluminescence data show the high emission intensity of the characteristic transitions 5 D 4 → 7 F J ( J =0–6), indicating that the BTC ligands are good sensitizers. The RE 3+ -(BTC) complexes act as efficient light conversion molecular devices (LCMDs) and can be used as tricolor luminescent materials.

  • Novel electroluminescent devices containing Eu3+-(2-acyl-1,3-indandionate) complexes with TPPO ligand
    Teotonio, Brito, Cremona, Quirino, Legnani and Felinto

    Optical Materials, ISSN: 09253467, Pages: 345-349, Published: December 2009 Elsevier
    Abstract Fabrication and electroluminescent properties of devices containing europium complexes of general formula [Eu(ACIND)3(TPPO)2], where ACIND, 2-acyl-1,3-indandionate ligands; and TPPO, triphenylphosphine oxide, as emitter layers are discussed. The double-layer devices based on these complexes present the following configurations: device 1: ITO/TPD/[Eu(AIND)3(TPPO)2]/Al; device 2: ITO/TPD/[Eu(ISOVIND)3(TPPO)2]/Al and device 3: ITO/TPD/[Eu(BIND)3(TPPO)2]/Al, where AIND, 2-acetyl-1,3-indandionate; ISOVIND, 2-isovaleryl-1,3-indandionate; and BIND, 2-benzoyl-1,3-indandionate, respectively. These devices exhibited photo and electroluminescent emissions. An important characteristic presented by devices is that their electroluminescent (EL) spectra, in the region of 5D0 → 7FJ (J = 0, 1, 2, 3 and 4) transitions of Eu3+ ion, show profiles that are different from photoluminescent (PL) ones. In addition to narrow bands arising from intraconfigurational-4f6 transitions, devices 1 and 2 also exhibited a broad band with maximum at around 500 nm which is assigned to electrophosphorescence from the indandionate ligands. On the other hand, EL spectra of device 3 present only narrow bands from 5D0 → 7FJ transitions. [Eu(ACIND)3(TPPO)2] complexes are promising candidates to prepare efficient organic light-emitting devices (OLEDs) when compared with those containing Eu3+-complexes of aliphatic β-diketonate anions.

  • Persistent luminescence of Eu2+ and Dy3+ doped barium aluminate (BaAl2O4:Eu2+,Dy3+) materials
    Stefani, Rodrigues, Carvalho, Felinto, Brito, Lastusaari and Hölsä

    Optical Materials, ISSN: 09253467, Pages: 1815-1818, Published: October 2009 Elsevier
    Abstract Polycrystalline Eu2+ and Dy3+ doped barium aluminate materials, BaAl2O4:Eu2+,Dy3+, were prepared with solid state reactions at temperatures between 700 and 1500 °C. The influence of the thermal treatments on the stability, homogeneity and structure as well as to the UV-excited and persistent luminescence of the materials was investigated by X-ray powder diffraction, SEM imaging and infrared spectroscopies as well as by steady state luminescence spectroscopy and persistent luminescence decay curves, respectively. The IR spectra of the materials prepared at 250, 700, and 1500 °C follow the formation of BaAl2O4 composition whereas the X-ray powder diffraction of compounds revealed how the hexagonal structure was obtained. The morphology of the materials at high temperatures indicated important aggregation due to sintering. The luminescence decay of the quite narrow Eu2+ band at ca. 500 nm shows the presence of persistent luminescence after UV irradiation. The dopant (Eu2+) and co-dopant (Dy3+) concentrations affect the crystallinity and luminescence properties of the materials.

  • Adsorption of di-2-pyridyl ketone salicyloylhydrazone on Amberlite XAD-2 and XAD-7 resins: Characteristics and isotherms
    Freitas, Iha, Felinto and Suárez-Iha

    Journal of Colloid and Interface Science, ISSN: 00219797, Volume: 323, Pages: 1-5, Published: 1 July 2008 Academic Press Inc.
    The adsorption of DPKSH onto Amberlite XAD-2 (styrene resin) and XAD-7 (acrylic ester resin) has been investigated, at (25+/-1) degrees C and pH 4.7. The experimental equilibrium data were fitted to the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) models. These three models provide a very good fit for both resins and the respective constants KL, KF, and KDR were calculated. For the same DPKSH concentration interval, the minimum time of contact for adsorption maximum at XAD-7 was smaller than at XAD-2 and the maximum amount of DPKSH adsorbed per gram of XAD-2 is smaller than at XAD-7. The investigation indicates that the mean sorption energy (E) characterizes a physical adsorption and the surfaces of both resins are energetically heterogeneous. The constants obtained in these studied systems were correlated and compared with those obtained for the silica gel/DPKSH system.

  • An electrospray ionization tandem mass spectrometric study of p-tert-butylcalix[6]arene complexation with ammonium hydroxide, and ammonium and sodium ions
    André Sassine, Helio A. Martins-Júnior, Daniel T. Lebre, Felipe Valli, Maria A. F. Pires, Oscar Vega, and Maria C. F. C. Felinto

    Rapid Communications in Mass Spectrometry, ISSN: 09514198, eISSN: 10970231, Pages: 385-393, Published: 2008 Wiley
    The formation of complexes involving p-tert-butylcalix[6]arene with neutral and charged species has been investigated by tandem mass spectrometry combined with electrospray ionization. Complexes of p-tert-butylcalix[6]arene with NH4+ ions were observed in the ratios 1:1, 2:1, and 3:1, together with the complexes of p-tert-butylcalix[6]arene with NH4OH and Na+ ions in the ratios 1:1:1, 2:1:1, and 3:1:1. A single 1:1 complex of p-tert-butylcalix[6]arene with Na+ ions was observed. In addition, a doubly charged complex of p-tert-butylcalix[6]arene with NH4OH, Na+, and NH4+ ions in the ratio 6:1:1:1 was observed. The identity of each complex was determined by mass analysis of product ions formed by the application of a declustering potential over the range 20-220 V and by observation of product ion mass spectra wherein the collision energy was varied from 5 to 50 eV. Fragmentation of the complexes is characterized by the facile loss of the ammonia molecule, sodium and ammonium ions, loss of neutral p-tert-butylcalix[6]arene, and successive neutral losses of C4H8 from the six tert-butyl groups in each p-tert-butylcalix[6]arene molecule.

  • Photoluminescence behavior of Eu3+ ion doped into γ- and α-alumina systems prepared by combustion, ceramic and Pechini methods
    M.A.F. Monteiro, H.F. Brito, M.C.F.C.M. Felinto, G.E.S. Brito, E.E.S. Teotonio, F.M. Vichi, and R. Stefani

    Microporous and Mesoporous Materials, ISSN: 13871811, Volume: 108, Issue: 1-3, Pages: 237-246, Published: 1 February 2008 Elsevier BV
    Abstract Al 2 O 3 :Eu 3+ (1%) samples were prepared by combustion, ceramic, and Pechini methods annealed from 400 to 1400 °C. XRD patterns indicate that samples heated up to 1000 °C present disordered character of activated alumina (γ-Al 2 O 3 ). However, α-Al 2 O 3 phase showed high crystallinity and thermostability at 1200–1400 °C. The sample characterizations were also carried out by means of infrared spectroscopy (IR), scanning electron microscopy (SEM) and specific surface areas analysis (BET method). Excitation spectra of Al 2 O 3 :Eu 3+ samples present broaden bands attributed to defects of Al 2 O 3 matrices and to LMCT state of O → Eu 3+ , however, the narrow bands are assigned to 7 F 0  →  5 D J , 5 H J and 5 L J transitions of Eu 3+ ion. Emission spectra of samples calcined up to 1000 °C show broaden bands for 5 D 0  →  7 F J transitions of Eu 3+ ion suggesting that the rare earth ion is in different symmetry sites showed by inhomogeneous line broadening of bands, confirming the predominance of the γ-alumina phase. For all samples heated from 1200 to 1400 °C the spectra exhibit narrow 5 D 0  →  7 F J transitions of Eu 3+ ion indicating the conversion of γ to α-Al 2 O 3 phases, a high intensity narrow peak around 695 nm assigned to R lines of Cr 3+ ion is shown. Al 2 O 3 :Eu 3+ heated up to 1100 °C presents an increase in the Ω 2 intensity parameter with the increase of temperatures enhancing the covalent character of metal–donor interaction. The disordered structural systems present the highest values of emission quantum efficiencies ( η ). CIE coordinates of Al 2 O 3 :Eu 3+ are also discussed.

  • Luminescent nanoparticles of MgAl2O4:Eu, Dy prepared by citrate sol-gel method
    Alessandra S. Maia, Roberval Stefani, Cláudia A. Kodaira, Maria C.F.C. Felinto, Ercules E.S. Teotonio, and Hermi F. Brito

    Optical Materials, ISSN: 09253467, Pages: 440-444, Published: October 2008/December 2008 Elsevier BV
    Abstract MgAl 2 O 4 :Eu, Dy nanoparticles were prepared by citrate sol–gel method and thermally treated at 600, 700, 800 and 900 °C. The trivalent europium ion is partially reduced to the divalent state at 700 and 800 °C. Infrared spectra of the phosphors showed bands around 700 and 520 cm −1 corresponding to the AlO 6 groups. X-ray diffraction patterns present sharp reflections of samples heated from 700 to 900 °C indicating the MgAl 2 O 4 spinel phase. Grain size in the range 20–30 nm were observed by measurement of transmission electron microscopy (TEM). The emission spectra of the phosphors show a broadened band at 480 nm assigned to the 4f 6 5d → 4f 7 ( 8 S 7/2 ) transition of Eu 2+ ion overlapped to the 4 F 9/2  →  6 H 15/2 transition of the Dy 3+ ion. Besides, the 4 F 9/2  →  6 H 13/2 transition (579 nm) of Dy 3+ ion is overlapped with the 5 D 0  →  7 F 0 (578 nm) and 5 D 0  →  7 F 1 (595 nm) transitions from the Eu 3+ ion. Excitation spectra of the sample heated at 900 °C monitoring the excitation at 615 nm of 5 D 0  →  7 F 2 transition of Eu 3+ ion exhibit a broad band assigned to the O → Eu 3+ ligand-to-metal charge-transfer states (LMCT) around 280 nm. The samples present green persistent luminescence after exposure to UV radiation. The chromaticity coordinates were obtained from the luminescence emission spectrum.

  • Evaluation of intramolecular energy transfer process in the lanthanide(III) bis- and tris-(TTA) complexes: Photoluminescent and triboluminescent behavior
    Ercules E.S. Teotonio, Gerson M. Fett, Hermi F. Brito, Wagner M. Faustino, Gilberto F. de Sá, Maria Cláudia F.C. Felinto, and Regina H.A. Santos

    Journal of Luminescence, ISSN: 00222313, Volume: 128, Pages: 190-198, Published: February 2008 Elsevier BV
    This work reports the energy transfer mechanism process of [Eu(TTA) 2 (NO 3 )(TPPO) 2 ] ( bis -TTA complex) and [Eu(TTA) 3 (TPPO) 2 ] ( tris -TTA complex) based on experimental and theoretical spectroscopic properties, where TTA=2-thienoyltrifluoroacetone and TPPO=triphenylphosphine oxide. These complexes were synthesized and characterized by elemental analyses, infrared spectroscopy and thermogravimetric analysis. The theoretical complexes geometry data by using Sparkle model for the calculation of lanthanide complexes (SMLC) is in agreement with the crystalline structure determined by single-crystal X-ray diffraction analysis. The emission spectra for [Gd(TTA) 3 (TPPO) 2 ] and [Gd(TTA) 2 (NO 3 )(TPPO) 2 ] complexes are associated to T→S 0 transitions centered on coordinated TTA ligands. Experimental luminescent properties of the bis -TTA complex have been quantified through emission intensity parameters Ω λ ( λ =2 and 4), spontaneous emission rates ( A rad ), luminescence lifetime ( τ ), emission quantum efficiency ( η ) and emission quantum yield ( q ), which were compared with those for tris -TTA complex. The experimental data showed that the intensity parameter value for bis -TTA complex is twice smaller than the one for tris -TTA complex, indicating the less polarizable chemical environment in the system containing nitrate ion. A good agreement between the theoretical and experimental quantum yields for both Eu(III) complexes was obtained. The triboluminescence (TL) of the [Eu(TTA) 2 (NO 3 )(TPPO) 2 ] complexes are discussed in terms of ligand-to-metal energy transfer.

  • Optical investigation of Y2 O3 : Sm3 + nanophosphor prepared by combustion and Pechini methods
    C.A. Kodaira, R. Stefani, A.S. Maia, M.C.F.C. Felinto, and H.F. Brito

    Journal of Luminescence, ISSN: 00222313, Volume: 127, Pages: 616-622, Published: December 2007 Elsevier BV
    Abstract Nanoparticles of trivalent samarium ion doped into yttrium oxide with attractive photoluminescent properties were prepared using combustion and Pechini methods treated at low heating temperatures. Combustion technique focused on an exothermic reaction between metal nitrates and glycine as fuel leading to the desired product where Y 2 O 3 : Sm 3 + nanophosphor was heated at 400, 500 and 600 ∘ C . For Pechini method, which is based upon in situ polyesterification between citric acid and ethylene glycol, the phosphor material was treated only at 600 ∘ C . The powders were characterized by X-ray diffraction, infrared absorption spectroscopy and scanning electronic microscopy. Photoluminescent study of Y 2 O 3 : Sm 3 + system showed the characteristic emission narrow lines containing ( J + 1 / 2 ) -manifolds of intraconfigurational G 5 / 2 4 → H J 6 transitions ( J = 5 2 , 7 2 , 9 2 and 11 2 ) of Sm 3 + ion with the G 5 / 2 4 → H 7 / 2 6 transition ( λ = 609 nm ) as a prominent intensity, when excitation was monitored at 406 nm ( H 5 / 2 6 → K 11 / 2 4 ) . The luminescence decay curves suggest a mono-exponential behavior.

  • The swelling behavior of chitosan hydrogels membranes obtained by UV- and γ-radiation
    M.C.F.C. Felinto, D.F. Parra, C.C. da Silva, J. Angerami, M.J.A. Oliveira, and A.B. Lugão

    Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms, ISSN: 0168583X, Volume: 265, Pages: 418-424, Published: December 2007 Elsevier BV
    In order to develop a non toxicity and biocompatible hydrogel system with potential ability in biotechnology based on membranes of polyethylene glycol (PEG 300 and 400) and chitosan were prepared under ultraviolet light (UV) and γ-radiation curing, at room temperature. The hydrogels were characterized by FTIR spectroscopic, UV absorption spectroscopy, thermal analysis and scanning electronic microscopy. The swelling behaviors were investigated in terms of time of swelling, irradiation time, and pH. The hydrogel with PEG 300 showed unusual swelling behavior.

  • Novel unexpected Tb3+ coordination polymer containing two carboxylate ligands: Syntheses, structure and photoluminescent properties
    Ercules E.S. Teotonio, Gerson M. Fett, Hermi F. Brito, Antônio C. Trindade, and Maria Cláudia F.C. Felinto

    Inorganic Chemistry Communications, ISSN: 13877003, Pages: 867-872, Published: August 2007 Elsevier BV
    Abstract Novel unexpected coordination polymer [Tb(PHTHGLY)(CBGLY)(H 2 O) 2 ](H 2 O) 3 complex containing simultaneously N -phthaloylglycinate and N -(2-carboxybenzoyl)glycinate ligands has been prepared and characterized by single crystal X-ray structure, thermogravimetric analysis and infrared spectroscopy. The X-ray crystal diffraction indicates that the Tb 3+ -complex crystallizes in a triclinic crystal system and space group P 1 ¯ , forming a 1D polymer where carboxylate groups bridge the Tb 3+ ions. The photoluminescence data revel that the ligands act as efficient “antennas” sensitizing the luminescence of the Tb 3+ ion showing a strong green emission color arising from intraconfigurational 5 D 4  →  7 F J transitions ( J  = 0–6).

  • Highly enhanced luminescence of SrB4O7:Eu2+ phosphor prepared by the combustion method using glycine as fuel
    Roberval Stefani, Alessandra de S. Maia, Cláudia A. Kodaira, Ercules E.S. Teotonio, Maria C.F.C. Felinto, and Hermi F. Brito

    Optical Materials, ISSN: 09253467, Pages: 1852-1855, Published: August 2007 Elsevier BV
    Abstract Eu2+ ion doped into SrB4O7 matrix was prepared by combustion method heated at 900 °C in air, using urea (U) or glycine (G) as fuels in different ratios (U100, A10, A25, G10, G25, G75, and G100). In some compositions, ammonium acetate (AA) was used to reduce the exothermicity of combustion reaction. X-ray diffraction and luminescence spectroscopy were used to characterize the material. The high intense emission band at 367 nm is assigned to 4f65d → 4f7(8S7/2) transition arisen from divalent europium ion. It is observed that the interconfigurational transition is dependent on the molar ratio of glycine:urea fuels. Glycine fuel favors Eu2+ formation in SrB4O7 host lattice prepared by combustion method.

  • Synthesis and luminescent properties of Eu3+-complexes with 2-acyl-1,3-indandionates (ACIND) and TPPO ligands: The first X-ray structure of Eu-ACIND complex
    Ercules E.S. Teotonio, Hermi F. Brito, Hans Viertler, Wagner M. Faustino, Oscar L. Malta, Gilberto F. de Sá, Maria Cláudia F.C. Felinto, Regina H.A. Santos, and Marco Cremona

    Polyhedron, ISSN: 02775387, Pages: 3488-3494, Published: 25 December 2006 Elsevier BV
    Abstract Europium complexes presenting general formulas [Eu(ACIND)3(H2O)2] and [Eu(ACIND)3(TPPO)2] have been synthesized and characterized. In these formulas ACIND is stands for the ligands 2-acetyl-1,3-indandionate (AIND), 2-isovaleryl-1,3-indandionate (ISOVIND) or 2-benzyl-1,3-indandionate (BIND). The [Eu(ISOVIND)3(H2O)(EtOH)] complex was also prepared and its structure determined by single crystal X-ray analysis, showing that this complex crystallize in a monoclinic space group P21/n with the water molecules bridging through the hydrogen bond. The Eu(III) ion is eight-coordinate in a bicapped trigonal prismatic geometry defined by the oxygen donor atoms with a site of symmetry close to C2ν. Isovaleryl groups in the ISOVIND molecules in the structure are disordered over two positions of the europium complex. Carbon atoms in ethanol molecule are disordered by the thermal vibration. Photoluminescence properties of these complexes in solid state were investigated both experimentally and theoretically, suggesting an efficient ligand-to-metal intramolecular energy transfer process.

  • Photoluminescent behavior of SrB4O7:RE2+ (RE=Sm and Eu) prepared by Pechini, combustion and ceramic methods
    R. Stefani, A.D. Maia, E.E.S. Teotonio, M.A.F. Monteiro, M.C.F.C. Felinto, and H.F. Brito

    Journal of Solid State Chemistry, ISSN: 00224596, eISSN: 1095726X, Volume: 179, Pages: 1086-1092, Published: April 2006 Elsevier BV
    This work reports the preparation of system containing RE 2+ ions (RE ¼ Sm and Eu)-doped in SrB4O7 matrix by ceramic, Pechini and combustion methods. These compounds were prepared by reduction of RE 3+ to RE 2+ in air, which exhibit some different features according to the preparation method. Photoluminescent properties of these systems were investigated based on the emission and excitation spectral data. The emission spectra of SrB4O7:Eu 2+ system prepared by combustion and Pechini methods are characterized by a broad band assigned to interconfigurational 4f 6 5d-4f 7 transition, while SrB4O7:Sm 2+ compound exhibit narrow emission bands arising from intraconfigurational-4f 6 also shows 4 G5/2- 6 HJ0 transitions (J 0 ¼ 5 ; 7 ; 9 and 11 2 ) arising from Sm 3+ ion, transitions. SrB4O7:RE system prepared by combustion method presents emission bands from RE 3+ ions as intense as that arising from RE 2+ , suggesting that the preparation route is not efficient for the reduction RE 3+ -RE 2+ process. Emission quantum efficiency and radiative emission rates of Sm 2+ ion are determined and discussed.

  • Preparation, crystal structure and optical spectroscopy of the rare earth complexes (RE3+=Sm, Eu, Gd and Tb) with 2-thiopheneacetate anion
    Ercules E.S. Teotonio, Hermi F. Brito, Maria Cláudia F.C. Felinto, Larry C. Thompson, Victor G. Young, and Oscar L. Malta

    Journal of Molecular Structure, ISSN: 00222860, Volume: 751, Issue: 1-3, Pages: 85-94, Published: 15 September 2005 Elsevier BV
    Abstract Rare earth complexes with the formulae Sm(TPAC)3·3H2O, Eu2(TPAC)6·5.25H2O and RE(TPAC)3·3.5H2O (where RE=Gd and Tb), and TPAC=2-thiopheneacetate) have been synthesized and characterized by complexometric titration, elemental analyses, infrared spectroscopy, and X-ray crystallography. Infrared data suggested the presence of both bridging and chelating TPAC anions. The crystal structure of the [Eu2(TPAC)6·(H2O)3]·2.25H2O complex in the solid state, determined by X-ray diffraction, revealed that it crystallizes in the orthorhombic crystal system (space group Aba2), with two crystallographically independent Eu3+ centers (Eu1 and Eu2). These europium centers are held together by one bidentate bridging and two tridentate bridging carboxylate groups. The existence of two Eu3+ centers was also supported by the emission spectrum. The luminescence properties of the RE–TPAC complexes were investigated by measuring the excitation and emission spectra, and the intramolecular ligand-to-rare earth energy transfer mechanisms were discussed. The emission spectra of the Eu3+ and Tb3+ ions displayed only narrow bands arising from 5D0→7F0 and 5D0→7F0–4 transitions, respectively, indicating an efficient luminescence sensitization of these ions by the TPAC ‘antenna’. On the other hand, the emission spectrum of the Sm3+-complex displayed a broad band from the phosphorescence of the TPAC ligand which overlapped the 4f5-intraconfigurational transitions. The theoretical intensity parameters Ωλ (λ=2 and 4), maximum splitting of the 7F1 state (ΔE) and the ratio between the 5D0→7F0 and 5D0→7F2 transition intensities (R02) were calculated based on the X-ray crystalline structure for the Eu3+-complex, and a comparison with experimental data were made. The emission quantum efficiency (η) of the D 5 emitting level of the Eu3+ ion was also determined.

  • Synthesis and spectroscopic behavior of highly luminescent Eu 3+-dibenzoylmethanate (DBM) complexes with sulfoxide ligands
    E. Niyama, H.F. Brito, M. Cremona, E.E.S. Teotonio, R. Reyes, G.E.S. Brito, and M.C.F.C. Felinto

    Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, ISSN: 13861425, Issue: 11-12, Pages: 2643-2649, Published: September 2005 Elsevier BV
    In this paper the synthesis, characterization and photoluminescent behavior of the [RE(DBM)3L2] complexes (RE=Gd and Eu) with a variety of sulfoxide ligands; L=benzyl sulfoxide (DBSO), methyl sulfoxide (DMSO), phenyl sulfoxide (DPSO) and p-tolyl sulfoxide (PTSO) have been investigated in solid state. The emission spectra of the Eu(3+)-beta-diketonate complexes show characteristics narrow bands arising from the 5D0-->7F(J) (J=0-4) transitions, which are split according to the selection rule for C(n), C(nv) or C(s) site symmetries. The experimental Judd-Ofelt intensity parameters (Omega2 and Omega4), radiative (A(rad)) and non-radiative (A(nrad)) decay rates, and R02 for the europium complexes have been determined and compared. The highest value of Omega2 (61.9x10(-20)cm2) was obtained to the complex with PTSO ligand, indicating that Eu3+ ion is in the highly polarizable chemical environment. The higher values of the experimental quantum yield (q) and emission quantum efficiency of the emitter 5D0 level (eta) for the Eu-complexes with DMSO, DBSO and PTSO sulfoxides suggest that these complexes are promising Light Conversion Molecular Devices (LCMDs). The lower value of quantum yield (q=1%), for the hydrated complex [Eu(DBM)3H2O], indicates that the luminescence quenching occurs via multiphonon relaxation by coupling with the OH-oscillators from water molecule coordinated to rare earth ion. The pure red emission of the Eu-complexes has been confirmed by (x, y) color coordinates.

  • Magnetic polymeric microspheres for protein adsorption
    M.C.F.C. Felinto, D.F. Parra, A.B. Lugão, M.P. Batista, O.Z. Higa, M. Yamaura, R.L. Camilo, M.T.C.P. Ribela, and L.C. Sampaio

    Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms, ISSN: 0168583X, Volume: 236, Issue: 1-4, Pages: 495-500, Published: July 2005 Elsevier BV
    Abstract Magnetic beads consisting of polymer-coated manganese ferrite nanoparticles were prepared by the precipitation reaction of manganese ferrite into the channels of methyl methacrylate polymer beads by sodium hydroxide, resulting in MnMagBead. MnMagBead was characterized by infrared spectra (FTIR), thermogravimetric analysis of TGA/DTG and indicates the presence of –CO (carbonyl) groups and the MnFe2O4 on the beads. Magnetization measurements were obtained at room temperature in magnetic fields up to 10 KOe using a vibrating sample magnetometer. Introductory Protein adsorption biological tests were processed using labeled I-125 albumin (BSA), and the activity was measured in a gamma counting spectrometer. These superparamagnetic beads exhibit the capacity to bind biological molecules such as proteins like albumin, with a good capability (5 × 10−6) μg/100 mg of beads as compared with other magnetic resins studied in our group.

  • Synthesis, crystalline structure and photoluminescence investigations of the new trivalent rare earth complexes (Sm3+, Eu3+ and Tb3+) containing 2-thiophenecarboxylate as sensitizer
    Ercules E.S Teotonio, Maria Cláudia F.C Felinto, Hermi F Brito, Oscar L Malta, Antônio C Trindade, Renato Najjar, and Wieslaw Strek

    Inorganica Chimica Acta, ISSN: 00201693, Volume: 357, Pages: 451-460, Published: 30 January 2004 Elsevier BV
    Abstract New complexes with the general formula [RE(TPC) 3  · (H 2 O) 2 ], where RE=Eu 3+ , Sm 3+ , Gd 3+ , Tb 3+ and TPC=2-thiophenecarboxylate, have been prepared and investigated by photoluminescence spectroscopy. These compounds were characterized by complexometric titration, elemental analyses and infrared spectroscopy. The X-ray crystal structure has been determined for the [Eu(TPC) 3  · (H 2 O) 2 ] compound, indicating that this complex is in dimeric form bridged by two carboxylate ions with monoclinic crystal system and space group P 2 1 / n . The coordination polyhedron can be described as a distorted square antiprism, where six oxygen atoms belong to the TPC ligand and two oxygen atoms belong to the water molecules, with site symmetry close to C 2 v . The theoretical value of the intensity parameter Ω 2 , which is in agreement with the experimental one, indicates that the Eu 3+ ion is in a highly polarizable chemical environment. Based on the luminescence spectra, the energy transfer from the ligand triplet state (T) of TPC to the excited levels of the Eu 3+ ion is discussed. The emission quantum efficiency of the 5 D 0 emitting level of the Eu 3+ ion was also determined. In the case of the Tb 3+ ion, the photoluminescence data show the high emission intensity of the characteristic transitions 5 D 4  →  7 F J ( J =0–6), indicating that the TPC ligand is a good sensitizer. It is also noticed that the complexes with the Eu 3+ and Tb 3+ ions are more luminescent than the complex with the Sm 3+ ion.

  • Photoluminescence behavior of the Sm3+ and Tb3+ ions doped into the Gd2(WO4)3 matrix prepared by the Pechini and ceramic methods
    Cláudia A. Kodaira, Hermi F. Brito, Ercules E. S. Teotonio, Maria Cláudia F. C. Felinto, Oscar L. Malta, and Giancarlo E. S. Brito

    Journal of the Brazilian Chemical Society, ISSN: 01035053, Pages: 890-896, Published: November/December 2004 FapUNIFESP (SciELO)
    The Gd2(WO4)3:RE3+ compounds (where RE3+ = Sm and Tb) were prepared by the Pechini and ceramic methods and characterized by X-ray diffraction and infrared spectroscopy. These rare earth materials present high orange (Sm3+-compound) and green (Tb3+-compound) luminescence intensity under UV radiation. The excitation spectra of these compounds presented broad bands arising from ligand-to-metal charge transfer (O®W and O®RE3+) and narrow bands from 4f-intraconfigurational transitions. The excitation spectra of Tb3+ system also exhibit broad bands attributed to the interconfigurational transition (4f-5d). The emission spectra exhibited the 4G5/2®6HJ (J = 5/2, 7/2, 9/2 and 11/2) and 5D4® 7FJ (J = 0-6) transitions (direct excitation), for the systems doped with Sm3+ and Tb3+, respectively, while a broad band assigned to the LMCT (O®W) is observed when the excitation is monitored on the O®W LMCT state around 270 nm. The experimental intensity parameters hSm and hEu present similar behaviors, suggesting that the Sm3+ ion is in a highly polarizable chemical environment with similar covalent character of the metal-donor atom interaction to the tungstate doped europium system. The cross-relaxation process from the 5D3 to the 5D4 levels of the Gd2(WO4)3:Tb3+ system has been also reported.

  • Luminescence investigations on Eu(III) thenoyltrifluoroacetonate complexes with amide ligands
    Ercules E.S. Teotonio, Hermi F. Brito, Maria Cláudia F.C. Felinto, Cláudia A. Kodaira, and Oscar L. Malta

    Journal of Coordination Chemistry, ISSN: 00958972, Pages: 913-921, Published: 10 July 2003 Informa UK Limited
    The influence of amide ligands on the photoluminescent behavior of tris(thenoyltrifluoroacetonate)- europium(III) in the solid state is reported. Elemental analysis showed that these compounds have the following formulas [Eu(TTA)3·(ANL)2] and [Eu(TTA)3·PZA], where ANL = acetanilide and PZA = pyrazinamide. The photoluminescence spectra of the complexes recorded in the range 420-720 nm at 77 K show narrow bands arising from the 5D0 → 7F J transitions (where J = 0-4), under excitation at 394 nm. Based on the emission spectra and luminescence decay curves the intensity parameters (Ωλ), lifetime (τ) and emission quantum efficiency (η) were determined. The Ω2 values indicate that the Eu3+ion in these complexes is in a highly polarizable chemical environment. The higher value of η (60%) obtained for the complex with the ANL ligand, in comparison with the complex with the PZA ligand (30%), indicates a more efficient deactivation of the Eu3+ion in the [Eu(TTA)3·PZA] complex.

  • Luminescence investigation of Eu3+ ion in the RE2(WO4)3 matrix (RE = La and Gd) produced using the Pechini method
    Cláudia A. Kodaira, Hermi F. Brito, and Maria Cláudia F.C. Felinto

    Journal of Solid State Chemistry, ISSN: 00224596, Volume: 171, Issue: 1-2, Pages: 401-407, Published: 2003 Elsevier BV
    The preparation, characterization and photoluminescent study of Eu 3+ ions doped into the RE 2 (WO 4 ) 3 matrix (RE= La and Gd), which was produced by the Pechini method at 750°C are reported. This method is based on polyesterification between citric acid and ethylene glycol, producing a material at low temperature. The X-ray diffraction patterns of the powder materials show the characteristic lines of the rare-earth tungstates. The infrared data are compatible with a T d point group symmetry for the tungsten atom units in both compounds. The excitation spectra of these systems (λ em = 615 nm) showed an intense broad band with maximum at 265 nm related to the O→W ligand-to-metal charge-transfer state. The emission spectra of the Eu 3+ ion (λ excitation = 393 nm) presented peaks arising from the 5 D J → 7 F J , transitions (J=0-3 and J' = 0-4) and are compatible with a C nv symmetry. The values of Ω 2 experimental intensity parameters (25.8 × 10 -20 and 21.5 x 10 -20 cm 2 for La 3+ and Gd 3+ ions, respectively), reflect the hypersensitive character of the 5 D 0 → 7 F 2 transition and indicate that the Eu 3+ ion is in a highly polarizable chemical environment, suggesting a considerable covalent character of the metal-donor atom interaction. The high emission quantum efficiencies of the RE 2 (WO 4 ) 3 :Eu 3+ materials (68% for La 3+ and 64% for Gd 3+ ) suggest that these systems are promising phosphors. The CIE chromaticity coordinates indicate that they are comparable to those of the commercially available red phosphor in cathode ray tubes.

  • Preparation and optical properties of trivalent europium doped into cordierite using the sol-gel process
    Gilmar P. Thim, Hermi F. Brito, Sandra A. Silva, Maria A.S. Oliveira, and Maria C.F.C. Felinto

    Journal of Solid State Chemistry, ISSN: 00224596, Volume: 171, Issue: 1-2, Pages: 375-381, Published: 2003 Elsevier BV
    The photoluminescence properties of the Eu 3+ ion doped into α-cordierite were studied based on the excitation and emission spectra and lifetime measurements. These samples were prepared by the sol-gel method and calcined by heating the xerogel at different temperatures: 873, 1133, 1223 and 1473 K. X-ray diffraction patterns were used to characterize the luminescent material. The 5 D 0 → 7 F 0 transition of the samples exhibits only one broad peak arising from the inhomogeneous linewidth of the amorphous phase, except for the ceramic material obtained at 1473 K that presents two peaks. Also, in the latter case the luminescence decay lifetime exhibits a bi-exponential fit when excited at 280 nm, corroborating that the Eu 3+ ion exists in two sites of symmetry. The experimental intensity parameter Ω 2 (10.0 x 10 -20 cm 2 ) indicates a moderately polarizable chemical environment around the Eu 3+ ion. The emission spectra of the Mg 2 Al 4 Si 5 O 18 :Eu 3+ samples calcined at 873, 1133 and 1223 K also presented inhomogeneous profiles for the 5 D 0 → 7 F J transitions suggesting disorder of the material. On the other hand, the sample calcined at 1473 K shows narrow bands indicating the crystalline form. The emission quantum efficiency (η) of the α-cordierite system is also discussed.

  • Synthesis and luminescent properties of supramolecules of β-diketonate of Eu(III) and crown ethers as ligands
    Maria Claudia F.C. Felinto, Claudia S. Tomiyama, Hermi F. Brito, Ercules E.S. Teotonio, and Oscar L. Malta

    Journal of Solid State Chemistry, ISSN: 00224596, Volume: 171, Issue: 1-2, Pages: 189-194, Published: 2003 Elsevier BV
    This work reports the synthesis and luminescence behavior of the diaquatris(thenoyltrifluoracetonate)europium(III) with dibenzol8-crown-6 (DB18C6) and 18-crown-6 (18C6), in the solid state. The new compounds Eu(TTA) 3 (H 2 O) 2 (DB18C6) 2 and Eu(TTA) 3 (H 2 O) 2 (18C6) 2 were characterized by elemental analysis, infrared spectroscopy, thermalanalysis and scattering electronic microscopy. The emission spectra show narrow emission bands that arise from the 5 D 0 → 7 F J transitions (J = 0-4) of the Eu 3+ ion. The spectral data of the Eu(TTA) 3 (H 2 O) 2 (DB18C6) 2 and Eu(TTA) 3 (H 2 O) 2 (18C6) 2 compounds present, respectively, one and two peaks assigned to the 5 D 0 → 7 F 0 transition ( ∼ 578 nm), suggesting one and two sites of symmetry around the metal ion. In addition, the luminescence decay curves of these DB18C6 and 18C6 systems were better fitted by a mono- and bi-exponential decays, respectively. The values of the experimental intensity parameters (Ω λ ) indicate that the europium ion in the complexes is in a highly polarizable chemical environment. The values of emission quantum efficiencies for the two Eu(III)-supramolecular compounds are similar (η = 26%).

  • Synthesis and performance of organic-coated magnetite particles
    M Yamaura, R.L Camilo, and M.C.F.C Felinto

    Journal of Alloys and Compounds, ISSN: 09258388, Volume: 344, Issue: 1-2, Pages: 152-156, Published: 7 October 2002 Elsevier BV
    Abstract Polymeric-coated magnetite particles with an adsorbed layer of extractant have been synthesized and are being evaluated for application in the separation and recovery of low concentrations of europium from water solutions. Physical characterizations of the extractant adsorbed particles were performed by X-ray diffractometry, Scanning Electron Microscopy and FT-IR spectrometry. Metal separations have been performed at various HNO 3 concentrations. Separation efficiency of the polymeric magnetic particles and the equilibrium adsorption isotherm of europium were investigated. Moreover, the magnetic field effect in the separation using a magnet was also verified.

  • Luminescence investigation of the Sm(III)-β-diketonates with sulfoxides, phosphine oxides and amides ligands
    H.F Brito, O.L Malta, M.C.F.C Felinto, E.E.S Teotonio, J.F.S Menezes, C.F.B Silva, C.S Tomiyama, and C.A.A Carvalho

    Journal of Alloys and Compounds, ISSN: 09258388, Volume: 344, Issue: 1-2, Pages: 293-297, Published: 7 October 2002 Elsevier BV
    Abstract In this paper we report on a photoluminescent investigation of complexes involving Sm 3+ -β-diketonates with sulfoxides, phosphine oxides and amides ligands. In the synthesis of the coordination compounds we used samarium tris(thenoyltrifluoroacetonate) dihydrated precursor with the following ligands (L): DBSO and PTSO sulfoxides; TPPO phosphine oxide and (PHA) N -phenylacetamide. They have shown high orange luminescence characteristic of the Sm 3+ ion. The emission spectra of the Sm 3+ -complexes present narrow bands arising from the 4 G 5/2 → 6 H J ( J =5/2, 7/2, 9/2, 11/2) transitions with the hypersensitive 4 G 5/2 → 6 H 9/2 transition as a prominent group. It is observed an efficient intramolecular energy transfer from the triplet state (T) of the ligands to the emitting 4 G 5/2 state of the Sm 3+ ion. The experimental intensity parameters ( η Sm and η Eu ) for the Sm and Eu complexes have been determined and compared. The lifetimes ( τ ) of the emitting level 4 G 5/2 of the Sm-complexes are approximately 10 times higher than in the precursor compound [Sm(TTA) 3 ·(H 2 O) 2 ] indicating that radiative processes are operative in all the compounds due to the absence of multiphonon relaxation by coupling with the OH oscillators.

  • Solvent extraction separation of uranium (VI) with acetatecalix[n]arene and β-diketone (HTTA)
    M.C.F.C. Felinto and V.F. Almeida

    Journal of Alloys and Compounds, ISSN: 09258388, Volume: 303-304, Pages: 524-528, Published: 24 May 2000 Elsevier BV
    Abstract We have studied a new method for the solvent extraction separation of UO 2 2+ by four calix[ n ]arenes from acetate solutions. The solvent extraction of UO 2 2+ with these calix[ n ]arenes and thenoyltrifluoroacetone (HTTA) in toluene has been studied in the presence or absence of alkali ion (Na + ). The efficiency of extraction increases drastically in the presence of alkali ions, due to the formation of heteronuclear complexes. Synergistic extraction was observed with calix[ n ]arenes and thenoyltrifluoroacetone (HTTA). Absorption spectra show shifts of characteristics bands of calix[ n ]arenes from the ultraviolet region to the visible region with a gap of 100 nm when HTTA is in the solution

  • Comparison of column chromatographic and precipitation methods for the purification of a macrocyclic polyether extractant
    MARK L. DIETZ, CLAUDIA FELINTO, SUSAN RHOADS, MAUREEN CLAPPER, JEFFREY W. FINCH, and BENJAMIN P. HAY

    Separation Science and Technology, ISSN: 01496395, Pages: 2943-2956, Published: 1999 Informa UK Limited
    Column chromatography on aminopropyl-derivatized silica and precipitation of a complex with perchloric acid have been evaluated as methods for the purification of di-tert-butylcyclohexano-18-crown-6 (DtBuCH18C6), a compound frequently employed for the selective extraction of strontium from acidic nitrate media. Both methods are shown to provide a simple and effective means of eliminating inactive sample components (i.e., impurities or stereoisomers incapable of extracting strontium) from the crown ether and enriching the material in 4(z),4′(z) cis-syn-cis DtBuCH18C6, a stereoisomer capable of highly efficient strontium extraction.

  • A lead-selective extraction chromatographic resin and its application to the isolation of lead from geological samples
    E. Philip Horwitz, Mark L. Dietz, Susan Rhoads, Claudia Felinto, Noel H. Gale, and Judith Houghton

    Analytica Chimica Acta, ISSN: 00032670, Volume: 292, Pages: 263-273, Published: 11 July 1994 Elsevier BV
    A novel extraction chromatographic resin comprised of a 0.75 M solution of the macrocyclic polyether bis-4,4′(5′)-[tert.-butylcyclohexano]-18-crown-6 in isodecanol supported on an inert, polymeric substrate for the separation and preconcentration of lead from acidic media is described. The material is shown to retain lead efficiently and selectively over a wide range of nitric acid concentrations. Sorbed lead is readily recovered using any of a variety of complexing agents. The resin is demonstrated to be sufficiently stable to handle large sample volumes or to permit reuse. Application of the resin to the isolation of lead from geological samples for subsequent mass spectrometric determination of isotopic ratios is described.

  • Standard molar enthalpies of formation of Y2O3, Ho2O3, and Er2O3at the temperature 298.15 K
    Lester R. Morss, Paul P. Day, Claudia Felinto, and Hermi Brito

    The Journal of Chemical Thermodynamics, ISSN: 00219614, eISSN: 10963626, Pages: 415-422, Published: March 1993 Elsevier BV
    Samples of Y2O3, Ho2O3, and Er2O3 that were crystalline, but dissolved relatively rapidly, were synthesized by careful decomposition of the corresponding nitrates. Enthalpies of solution of high-purity samples of Y2O3, and Er2O3 were measured in hydrochloric acid of various concentrations using an existing calorimeter interfaced with a computer and an interactive set of computer written in LabVIEW (a Macintosh instrument software system) so that data-acquisition and interpretation for slow reactions could be carried out with the computer. The following molar enthalpies of formation ΔfHom at the temperature 298.15 K were calculated: Y2O3, -(1932.8±5.2) kJ·mol-1; Ho2O3, -(1887.3±13.7) kJ·mol-1; and Er2O3 -(1904.2±3.4) kJ·mol-1.

  • Lanthanide isothiocyanate complexes with 3-picoline-N-Oxide (3-picNO)
    G. Vicentini, M.C.França da Cunha, and L.B. Zinner

    Journal of The Less-Common Metals, ISSN: 00225088, Volume: 149, Pages: 255-259, Published: 15 April 1989 Elsevier BV
    Complexes of formula Ln(NCS)3 · x(3-picNO) (x = 4, Ln  La, Ce; x = 3.5, Ln  Nd· Tm; x = 3, Ln  Yb, Lu) were prepared and characterized. Conductance data together with IR spectra indicate coordination of the anion through the nitrogen. 3-picNO is bonded through the oxygen. X-ray patterns show the existence of three isomorphous series corresponding to the three different compositions. A C3v symmetry was attributed to the europium compound based on the emission spectrum. The spectroscopic parameters β, b12, δ, Bkq and Bqk were determined from the neodymium absorption and europium emission spectra. The oscillator strengths in nitromethane and acetonitrile solutions were also calculated.

RECENT SCHOLAR PUBLICATIONS

  • Synthesis, Structure Study, First-Principles Investigations and Luminescence Properties of Europium and Terbium Complexes
    B Ali, HA Stefani, M Imran, A Irfan, MA Assiri, MCFC Felinto, M Khalid, ...
    Journal of Fluorescence, 1-11 2020

  • Luminescence properties of the Ln–EDTA complexes covalently linked to the chitosan biopolymers containing β‐diketonate as antenna ligands
    IF Costa, GP Pires, JGP Espnola, HF Brito, MCFC Felinto, WM Faustino, ...
    Luminescence 35 (3), 365-372 2020

  • Highly sensitive and precise optical temperature sensors based on new luminescent Tb 3+/Eu 3+ tetrakis complexes with imidazolic counterions
    LB Guimares, AMP Botas, MCFC Felinto, RAS Ferreira, LD Carlos, ...
    Materials Advances 2020

  • Optical properties of Eu 3+ and Tb 3+-doped tin dioxide nanoparticles prepared by coprecipitation method
    FFS SALVADOR, M FELINTO, LHC FRANCISCO, HP BARBOSA, ...
    2019

  • Development of highly luminescent PMMA films doped with Eu3+β-diketonate coordinated on ancillary ligand
    LHC Francisco, M Felinto, HF Brito, EES Teotonio, OL Malta
    Journal of Materials Science: Materials in Electronics 30 (18), 16922-16931 2019

  • Odd‐Even Effect on Luminescence Properties of Europium Aliphatic Dicarboxylate Complexes
    IP Assuno, AN Carneiro Neto, RT Moura Jr, CCS Pedroso, IGN Silva, ...
    ChemPhysChem 20 (15), 1931-1940 2019

  • Tuning Emitting Color of Electroluminescent Devices Containing Tris (2-acyl-1, 3-indandionate) aluminum (III) Complexes as Emitting Layers
    IF Costa, JL Moura, RE Aderne, HC Avila, M Cremona, HF Brito, ...
    Journal of the Brazilian Chemical Society 30 (8), 1647-1656 2019

  • Investigation on the formation of highly luminescent β-diketone-Ln (III)-EDTA water-soluble complexes
    HRM Silva, WM Faustino, EES Teotonio, HF Brito, OL Malta, ...
    Journal of Luminescence 207, 182-187 2019

  • Modeling intramolecular energy transfer in lanthanide chelates: A critical review and recent advances
    ANC Neto, EES Teotonio, GF de S, HF Brito, J Legendziewicz, ...
    Handbook on the Physics and Chemistry of Rare Earths 56, 55-162 2019

  • Nuclear based techniques in multifunctional materials characterization
    E BONTURIM, VL Mazzocchi, CBR Parentea, EG Moreira, ESM Seo, ...
    Instituto de Pesquisas Energticas e Nucleares 2018

  • White light emission of the single-phase CaWO4: Dy3+ phosphors by simple synthesis and fast heating
    HP Barbosa, C PEDROSO, MCFC Felinto, OL Malta, HF Brito
    2018

  • Persistent luminescence of inorganic nanophosphors prepared by wet-chemical synthesis
    E Bonturim, LG Merzio, R dos Reis, HF Brito, LCV Rodrigues, ...
    Journal of Alloys and Compounds 732, 705-715 2018

  • Synthesis and photoluminescence properties of [Eu (dbm) 3 PX] and [Eu (acac) 3 PX] complexes
    TA Kovacs, MCFC Felinto, TB Paolini, B Ali, LKO Nakamura, ...
    Journal of Luminescence 193, 98-105 2018

  • Rare Earth-Indomethacinate Complexes with Heterocyclic Ligands: Synthesis and Photoluminescence Properties
    JBM Resende Filho, PR Santos, JA Vale, WM Faustino, DS Farias, ...
    Journal of the Brazilian Chemical Society 28 (12), 2281-2290 2017

  • Photoluminescence of single-phased white light emission materials based on simultaneous Tb3+, Eu3+ and Dy3+ doping in CaWO4 matrix
    HP Barbosa, IGN Silva, MCFC Felinto, EES Teotonio, OL Malta, HF Brito
    Journal of Alloys and Compounds 696, 820-827 2017

  • Endophytic bacteria and rare earth elements; promising candidates for nutrient use efficiency in plants
    KR Prieto, F Echaide-Aquino, A Huerta-Robles, HP Valrio, ...
    Plant Macronutrient Use Efficiency, 285-306 2017

  • Building block magneto-luminescent nanomaterials of iron-oxide/ZnS@ LaF 3: Ce 3+, Gd 3+, Tb 3+ with green emission
    N Shrivastava, LU Khan, ZU Khan, JM Vargas, O Moscoso-Londoo, ...
    Journal of Materials Chemistry C 5 (9), 2282-2290 2017

  • Efficient multicolor tunability of ultrasmall ternary-doped LaF 3 nanoparticles: Energy conversion and magnetic behavior
    N Shrivastava, LU Khan, JM Vargas, C Ospina, JAQ Coaquira, ...
    Physical Chemistry Chemical Physics 19 (28), 18660-18670 2017

  • Optical and magnetic nanocomposites containing Fe3O4@ SiO2 grafted with Eu3+ and Tb3+ complexes
    LU Khan, D Muraca, HF Brito, O Moscoso-Londoo, M Felinto, KR Pirota, ...
    Journal of Alloys and Compounds 686, 453-466 2016

  • Partculas magnticas luminescentes para biomarcao
    JFZ REIS, MCFC FELINTO, PIDEB DE INICIAO, DEBEIC PROGRAMA, ...
    2016

MOST CITED SCHOLAR PUBLICATIONS

  • Luminescence investigation of Eu3+ ion in the RE2 (WO4) 3 matrix (RE= La and Gd) produced using the Pechini method
    CA Kodaira, HF Brito, MCFC Felinto
    Journal of Solid State Chemistry 171 (1-2), 401-407 2003
    Citations: 228

  • Luminescence investigation of the Sm (III)-β-diketonates with sulfoxides, phosphine oxides and amides ligands
    HF Brito, OL Malta, MCFC Felinto, EES Teotonio, JFS Menezes, ...
    Journal of alloys and compounds 344 (1-2), 293-297 2002
    Citations: 119

  • A lead-selective extraction chromatographic resin and its application to the isolation of lead from geological samples
    EP Horwitz, ML Dietz, S Rhoads, C Felinto, NH Gale, J Houghton
    Analytica Chimica Acta 292 (3), 263-273 1994
    Citations: 115

  • Synthesis and spectroscopic behavior of highly luminescent Eu3+–dibenzoylmethanate (DBM) complexes with sulfoxide ligands
    E Niyama, HF Brito, M Cremona, EES Teotonio, R Reyes, GES Brito, ...
    Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 61 (11 2005
    Citations: 110

  • Discovery of the Persistent Luminescence Mechanism of CdSiO3:Tb3+
    LCV Rodrigues, HF Brito, J Hölsä, R Stefani, MCFC Felinto, ...
    The Journal of Physical Chemistry C 116 (20), 11232-11240 2012
    Citations: 103

  • Evaluation of intramolecular energy transfer process in the lanthanide (III) bis-and tris-(TTA) complexes: Photoluminescent and triboluminescent behavior
    EES Teotonio, GM Fett, HF Brito, WM Faustino, GF de S, MCFC Felinto, ...
    Journal of Luminescence 128 (2), 190-198 2008
    Citations: 89

  • Synthesis, crystalline structure and photoluminescence investigations of the new trivalent rare earth complexes (Sm3+, Eu3+ and Tb3+) containing 2-thiophenecarboxylate as
    EES Teotonio, MCFC Felinto, HF Brito, OL Malta, AC Trindade, R Najjar, ...
    Inorganica chimica acta 357 (2), 451-460 2004
    Citations: 86

  • Optical investigation of Y2O3: Sm3+ nanophosphor prepared by combustion and Pechini methods
    CA Kodaira, R Stefani, AS Maia, M Felinto, HF Brito
    Journal of luminescence 127 (2), 616-622 2007
    Citations: 82

  • Photoluminescent behavior of SrB4O7: RE2+ (RE= Sm and Eu) prepared by Pechini, combustion and ceramic methods
    R Stefani, AD Maia, EES Teotonio, MAF Monteiro, M Felinto, HF Brito
    Journal of Solid State Chemistry 179 (4), 1086-1092 2006
    Citations: 78

  • Persistent luminescence of Eu2+ and Dy3+ doped barium aluminate (BaAl2O4: Eu2+, Dy3+) materials
    R Stefani, LCV Rodrigues, CAA Carvalho, MCFC Felinto, HF Brito, ...
    Optical Materials 31 (12), 1815-1818 2009
    Citations: 75

  • Synthesis and performance of organic-coated magnetite particles
    M Yamaura, RL Camilo, M Felinto
    Journal of alloys and compounds 344 (1-2), 152-156 2002
    Citations: 70

  • Luminescent nanoparticles of MgAl2O4: Eu, Dy prepared by citrate sol–gel method
    AS Maia, R Stefani, CA Kodaira, MCFC Felinto, EES Teotonio, HF Brito
    Optical Materials 31 (2), 440-444 2008
    Citations: 69

  • Preparation, crystal structure and optical spectroscopy of the rare earth complexes (RE3+= Sm, Eu, Gd and Tb) with 2-thiopheneacetate anion
    EES Teotonio, HF Brito, MCFC Felinto, LC Thompson, VG Young, ...
    Journal of molecular structure 751 (1-3), 85-94 2005
    Citations: 64

  • Luminescence phenomena involving metal enolates
    H Felinto Brito, O Manoel Loureiro Malta, ...
    PATAI'S Chemistry of Functional Groups 2009
    Citations: 63

  • Thermoluminescence and synchrotron radiation studies on the persistent luminescence of BaAl2O4: Eu2+, Dy3+
    LCV Rodrigues, R Stefani, HF Brito, M Felinto, J Hls, M Lastusaari, ...
    Journal of Solid State Chemistry 183 (10), 2365-2371 2010
    Citations: 56

  • Photoluminescence behavior of the Sm3+ and Tb3+ ions doped into the Gd2 (WO4) 3 matrix prepared by the Pechini and ceramic methods
    CA Kodaira, HF Brito, EES Teotonio, MCFC Felinto, OL Malta, GES Brito
    Journal of the Brazilian Chemical Society 15 (6), 890-896 2004
    Citations: 54

  • Synthesis and luminescent properties of supramolecules of β-diketonate of Eu (III) and crown ethers as ligands
    MCFC Felinto, CS Tomiyama, HF Brito, EES Teotonio, OL Malta
    Journal of Solid State Chemistry 171 (1-2), 189-194 2003
    Citations: 48

  • Luminescence investigations on Eu (III) thenoyltrifluoroacetonate complexes with amide ligands
    EES Teotonio, HF Brito, MCFC Felinto, CA Kodaira, OL Malta
    Journal of Coordination Chemistry 56 (10), 913-921 2003
    Citations: 47

  • Photoluminescence behavior of Eu3+ ion doped into γ-and α-alumina systems prepared by combustion, ceramic and Pechini methods
    MAF Monteiro, HF Brito, M Felinto, GES Brito, EES Teotonio, FM Vichi, ...
    Microporous and mesoporous materials 108 (1-3), 237-246 2008
    Citations: 44

  • Measurement and model calculation of the temperature dependence of ligand-to-metal energy transfer rates in lanthanide complexes
    WM Faustino, LA Nunes, IAA Terra, MCFC Felinto, HF Brito, OL Malta
    Journal of luminescence 137, 269-273 2013
    Citations: 43