The recent development of core/shell engineering of rare earth doped luminescent nanoparticles ha... more The recent development of core/shell engineering of rare earth doped luminescent nanoparticles has ushered a new era in fluorescence thermal biosensing, allowing for the performance of minimally invasive experiments, not only in living cells but also in more challenging small animal models. Here, the potential use of active-core/active-shell Nd(3+)- and Yb(3+)-doped nanoparticles as subcutaneous thermal probes has been evaluated. These temperature nanoprobes operate in the infrared transparency window of biological tissues, enabling deep temperature sensing into animal bodies thanks to the temperature dependence of their emission spectra that leads to a ratiometric temperature readout. The ability of active-core/active-shell Nd(3+)- and Yb(3+)-doped nanoparticles for unveiling fundamental tissue properties in in vivo conditions was demonstrated by subcutaneous thermal relaxation monitoring through the injected core/shell nanoparticles. The reported results evidence the potential of infrared luminescence nanothermometry as a diagnosis tool at the small animal level.
ABSTRACT The rare-earth metal organic chelate [Eu(btfa)3(MeOH)(bpeta)] (btfa, 4,4,4–trifluoro–1–p... more ABSTRACT The rare-earth metal organic chelate [Eu(btfa)3(MeOH)(bpeta)] (btfa, 4,4,4–trifluoro–1–phenyl–1,3–butanedionate; bpeta, 1,2–bis(4–pyridyl)ethane) has been used to dope a plastic optical fiber (POF) prepared by the bulk homopolymerization of hexamethylene diisocyanate (HMDI) catalysed by Tin(II)-2 ethylhexanoate (SnOct), to obtain a plastic optical fiber amplifier (POFA). The Eu3+ chelate, primarily added as luminophore for the amplification of the optical signal, showed an interesting co-catalytic activity in the polymerization of HMDI, that preferentially proceeded towards the formation of the highly stable polyisocyanurate trimer form thanks to its selective driving action, as demonstrated by 13C solid-state NMR. Pumping of the POFA with xenon lamps demonstrated the occurrence of stimulated emission inside the doped fiber.
ABSTRACT We have synthesized luminescent nanoparticles comprising a core of lanthanide complexes ... more ABSTRACT We have synthesized luminescent nanoparticles comprising a core of lanthanide complexes and shells of amorphous silica using reverse micelles as nanoreactors. 3-Hydroxypicolinate complexes of Eu(II), Tb(III), and the corresponding heteronuclear complexes have been investigated as the photoactive cores. The size of the silica particles is within the nanometer scale, which, together with the ability for surface biofunctionalization, opens up perspectives for their use in bioapplications. Optical studies of the as-prepared nanoparticles reveal that the luminescence properties of the 3-hydroxypicolinate complexes in the matrices are markedly different from their original features.
A new compound with the formula [Eu4(ETA)9(OH)3(H2O)3)], where ETA is ethyl 4,4,4-trifluoroacetoa... more A new compound with the formula [Eu4(ETA)9(OH)3(H2O)3)], where ETA is ethyl 4,4,4-trifluoroacetoacetate, has been synthesized and investigated by photoluminescence spectroscopy. The compound was characterized by means of chemical analysis, vibrational (IR), UV-vis absorption, and luminescence spectroscopies, and X-ray crystallography. The crystal structure of the [Eu4(ETA)9(OH)3(H2O)3)] complex in the solid state, determined by X-ray diffraction analysis, revealed that it crystallizes in the triclinic crystal system, space group P, with four crystallographically independent europium centers. From these structural data, the ground-state geometry of the tetramer has been calculated by using the Sparkle/AM1 model. The emission spectrum shows the characteristic transitions of the Eu3+ ion. The features displayed by the5D0-->7F0 transition in the emission spectrum are consistent with the Eu3+ ion occupying four different sites in chemical environments of low symmetries, in agreement with the X-ray data and the optimized geometry obtained from the Sparkle/AM1 model. These structural results have allowed the theoretical calculation of 4f-4f intensity parameters, including the forced electric dipole and dynamic coupling mechanisms as well as ligand singlet and triplet states, in good agreement with experiment.
Luminescent Eu(3+)-containing polyphosphate-tungstate aqueous colloidal systems were prepared and... more Luminescent Eu(3+)-containing polyphosphate-tungstate aqueous colloidal systems were prepared and studied as a function of the relative polyphosphate-tungstate content. In polyphosphate-rich solutions, Eu(3+) ions occupy cagelike sites composed of phosphate groups from the metaphosphate chains. In these sites, an average number of 0.5 water molecule coordinates to an Eu(3+) ion and the (5)D(0) emission quantum efficiency is 0.22. Tungstate addition leads to important modifications in neighboring Eu(3+) leading to coordination sites in the aqueous medium where metal ions are completely hidden from interactions with solvent molecules. Transmission electron microscopy results clearly show W-rich nanoparticles with sizes between 5 and 10 nm for all tungstate relative concentrations. For high tungstate relative contents (above 30 mol %), spectroscopic results suggest the presence of Eu(3+) in polyoxometalate (POM)-like sites by comparison with the well-known decatungstoeuropate [EuW(10)O(36)](9-) structure. These new aqueous colloids display surprisingly high (5)D(0) emission quantum efficiencies of ca 80% because of the strong ligand field provided by tungstate POM ligands and the complete absence of water molecules from the Eu(3+) first coordination shell.
ABSTRACT The local environment of Er3+ ions in microporous titanosilicate ETS-10 and in synthetic... more ABSTRACT The local environment of Er3+ ions in microporous titanosilicate ETS-10 and in synthetic narsarsukite and glassy materials obtained by calcination of ETS-10 has been investigated by EXAFS, Raman and photoluminescence spectroscopies. Er LIII-edge EXAFS studies of Er3+-doped ETS-10 support the view that the exchanged Er3+ ions reside close to the (negatively charged) TiO6 octahedra. In ETS-10, Er3+ is partially bonded to framework oxygen atoms and hydration water molecules. The ErTi distance (3.3 Å) is similar to the NaTi distances (3.15–3.20 Å) reported previously for Na–ETS-10. Although the exact location of the ErO6 units within the host structure of Er3+-doped synthetic narsarsukite is still an open question, it is most likely that Er3+ substitutes Ti4+ rather than Na+ ions. EXAFS spectroscopy indicates that no significant clustering of erbium atoms occurs in the titanosilicate samples studied. Evidence for the insertion of Er3+ ions in the framework of narsarsukite has been obtained by Raman spectroscopy. This is indicated by the increasing full-width at half-maximum (FWHM) of the 775 cm−1 peak and the increasing intensity of the anatase peaks as the erbium content increases. In addition, as the narsarsukite Er3+ content increases a band at ca. 515 cm−1 firstly broadens and subsequently a new peak appears at ca. 507 cm−1. Er3+-doped narsarsukite exhibits a characteristic local vibrational frequency, ħωca. 330 cm−1, with an electron–phonon coupling, gca. 0.2, which constitutes additional evidence for framework Er3+ insertion. The number of lines in the infrared emission spectrum of synthetic narsarsukite indicates the presence of two optically-active erbium centres with very similar local environments and an average 4I13/2 lifetime of 7.8 ± 0.2 ms.
A layered double hydroxide pillared by 2, 2&#... more A layered double hydroxide pillared by 2, 2'-bipyridine-5, 5'-dicarboxylate anions was used as a porous matrix to intercalate LnCl3 (Ln= Eu, Gd) at a loading of 0.6-0.7 mmol g-1. The hybrid materials were characterized by powder X-ray diffraction, IR and Raman ...
The photoluminescence features of Eu(3+)-, Tb(3+)-, Tb(3+)/Eu(3+)-alginate aerogel (hydrogel and ... more The photoluminescence features of Eu(3+)-, Tb(3+)-, Tb(3+)/Eu(3+)-alginate aerogel (hydrogel and alcogel) and Eu(3+)-alginate xerogel hybrids were investigated. The Eu(3+)-alginate aerogel and alcogel exhibit the highest (5)D0 quantum efficiencies (9.9 and 8.2%, respectively), while the hydrogel and xerogel have lower values (5.2 and 5.6%, respectively). The Tb(3+)/Eu(3+) hybrids are multiwavelength emitters in which the emission color can be tuned across the chromaticity diagram from the red toward the yellowish-green spectral regions, crossing the white area by selecting the excitation wavelength.
Page 1. Terbiumpolyoxotungstate Anions as Building Units to fabricate Nanostructured Films Filipa... more Page 1. Terbiumpolyoxotungstate Anions as Building Units to fabricate Nanostructured Films Filipa L. Sousa 1,a , Paula CR Soares-Santos 2,b , Helena IS Nogueira 2,c , Rute A. Sá Ferreira 3,d , Ana MV Cavaleiro 2,e , Luís D. Carlos 3,f , Tito Trindade 2,g ...
... PL, and excitation, PLE, spectra and time-resolved measurements were detected between 10 K an... more ... PL, and excitation, PLE, spectra and time-resolved measurements were detected between 10 K and RT on a modular double grating excitation spectrofluorimeter with a TRIAX 320 emission monochromator (Fluorolog-3, Jobin Yvon-Spex) coupled ... Bantignies, P. Dieudonné, JL. ...
The recent development of core/shell engineering of rare earth doped luminescent nanoparticles ha... more The recent development of core/shell engineering of rare earth doped luminescent nanoparticles has ushered a new era in fluorescence thermal biosensing, allowing for the performance of minimally invasive experiments, not only in living cells but also in more challenging small animal models. Here, the potential use of active-core/active-shell Nd(3+)- and Yb(3+)-doped nanoparticles as subcutaneous thermal probes has been evaluated. These temperature nanoprobes operate in the infrared transparency window of biological tissues, enabling deep temperature sensing into animal bodies thanks to the temperature dependence of their emission spectra that leads to a ratiometric temperature readout. The ability of active-core/active-shell Nd(3+)- and Yb(3+)-doped nanoparticles for unveiling fundamental tissue properties in in vivo conditions was demonstrated by subcutaneous thermal relaxation monitoring through the injected core/shell nanoparticles. The reported results evidence the potential of infrared luminescence nanothermometry as a diagnosis tool at the small animal level.
ABSTRACT The rare-earth metal organic chelate [Eu(btfa)3(MeOH)(bpeta)] (btfa, 4,4,4–trifluoro–1–p... more ABSTRACT The rare-earth metal organic chelate [Eu(btfa)3(MeOH)(bpeta)] (btfa, 4,4,4–trifluoro–1–phenyl–1,3–butanedionate; bpeta, 1,2–bis(4–pyridyl)ethane) has been used to dope a plastic optical fiber (POF) prepared by the bulk homopolymerization of hexamethylene diisocyanate (HMDI) catalysed by Tin(II)-2 ethylhexanoate (SnOct), to obtain a plastic optical fiber amplifier (POFA). The Eu3+ chelate, primarily added as luminophore for the amplification of the optical signal, showed an interesting co-catalytic activity in the polymerization of HMDI, that preferentially proceeded towards the formation of the highly stable polyisocyanurate trimer form thanks to its selective driving action, as demonstrated by 13C solid-state NMR. Pumping of the POFA with xenon lamps demonstrated the occurrence of stimulated emission inside the doped fiber.
ABSTRACT We have synthesized luminescent nanoparticles comprising a core of lanthanide complexes ... more ABSTRACT We have synthesized luminescent nanoparticles comprising a core of lanthanide complexes and shells of amorphous silica using reverse micelles as nanoreactors. 3-Hydroxypicolinate complexes of Eu(II), Tb(III), and the corresponding heteronuclear complexes have been investigated as the photoactive cores. The size of the silica particles is within the nanometer scale, which, together with the ability for surface biofunctionalization, opens up perspectives for their use in bioapplications. Optical studies of the as-prepared nanoparticles reveal that the luminescence properties of the 3-hydroxypicolinate complexes in the matrices are markedly different from their original features.
A new compound with the formula [Eu4(ETA)9(OH)3(H2O)3)], where ETA is ethyl 4,4,4-trifluoroacetoa... more A new compound with the formula [Eu4(ETA)9(OH)3(H2O)3)], where ETA is ethyl 4,4,4-trifluoroacetoacetate, has been synthesized and investigated by photoluminescence spectroscopy. The compound was characterized by means of chemical analysis, vibrational (IR), UV-vis absorption, and luminescence spectroscopies, and X-ray crystallography. The crystal structure of the [Eu4(ETA)9(OH)3(H2O)3)] complex in the solid state, determined by X-ray diffraction analysis, revealed that it crystallizes in the triclinic crystal system, space group P, with four crystallographically independent europium centers. From these structural data, the ground-state geometry of the tetramer has been calculated by using the Sparkle/AM1 model. The emission spectrum shows the characteristic transitions of the Eu3+ ion. The features displayed by the5D0-->7F0 transition in the emission spectrum are consistent with the Eu3+ ion occupying four different sites in chemical environments of low symmetries, in agreement with the X-ray data and the optimized geometry obtained from the Sparkle/AM1 model. These structural results have allowed the theoretical calculation of 4f-4f intensity parameters, including the forced electric dipole and dynamic coupling mechanisms as well as ligand singlet and triplet states, in good agreement with experiment.
Luminescent Eu(3+)-containing polyphosphate-tungstate aqueous colloidal systems were prepared and... more Luminescent Eu(3+)-containing polyphosphate-tungstate aqueous colloidal systems were prepared and studied as a function of the relative polyphosphate-tungstate content. In polyphosphate-rich solutions, Eu(3+) ions occupy cagelike sites composed of phosphate groups from the metaphosphate chains. In these sites, an average number of 0.5 water molecule coordinates to an Eu(3+) ion and the (5)D(0) emission quantum efficiency is 0.22. Tungstate addition leads to important modifications in neighboring Eu(3+) leading to coordination sites in the aqueous medium where metal ions are completely hidden from interactions with solvent molecules. Transmission electron microscopy results clearly show W-rich nanoparticles with sizes between 5 and 10 nm for all tungstate relative concentrations. For high tungstate relative contents (above 30 mol %), spectroscopic results suggest the presence of Eu(3+) in polyoxometalate (POM)-like sites by comparison with the well-known decatungstoeuropate [EuW(10)O(36)](9-) structure. These new aqueous colloids display surprisingly high (5)D(0) emission quantum efficiencies of ca 80% because of the strong ligand field provided by tungstate POM ligands and the complete absence of water molecules from the Eu(3+) first coordination shell.
ABSTRACT The local environment of Er3+ ions in microporous titanosilicate ETS-10 and in synthetic... more ABSTRACT The local environment of Er3+ ions in microporous titanosilicate ETS-10 and in synthetic narsarsukite and glassy materials obtained by calcination of ETS-10 has been investigated by EXAFS, Raman and photoluminescence spectroscopies. Er LIII-edge EXAFS studies of Er3+-doped ETS-10 support the view that the exchanged Er3+ ions reside close to the (negatively charged) TiO6 octahedra. In ETS-10, Er3+ is partially bonded to framework oxygen atoms and hydration water molecules. The ErTi distance (3.3 Å) is similar to the NaTi distances (3.15–3.20 Å) reported previously for Na–ETS-10. Although the exact location of the ErO6 units within the host structure of Er3+-doped synthetic narsarsukite is still an open question, it is most likely that Er3+ substitutes Ti4+ rather than Na+ ions. EXAFS spectroscopy indicates that no significant clustering of erbium atoms occurs in the titanosilicate samples studied. Evidence for the insertion of Er3+ ions in the framework of narsarsukite has been obtained by Raman spectroscopy. This is indicated by the increasing full-width at half-maximum (FWHM) of the 775 cm−1 peak and the increasing intensity of the anatase peaks as the erbium content increases. In addition, as the narsarsukite Er3+ content increases a band at ca. 515 cm−1 firstly broadens and subsequently a new peak appears at ca. 507 cm−1. Er3+-doped narsarsukite exhibits a characteristic local vibrational frequency, ħωca. 330 cm−1, with an electron–phonon coupling, gca. 0.2, which constitutes additional evidence for framework Er3+ insertion. The number of lines in the infrared emission spectrum of synthetic narsarsukite indicates the presence of two optically-active erbium centres with very similar local environments and an average 4I13/2 lifetime of 7.8 ± 0.2 ms.
A layered double hydroxide pillared by 2, 2&#... more A layered double hydroxide pillared by 2, 2'-bipyridine-5, 5'-dicarboxylate anions was used as a porous matrix to intercalate LnCl3 (Ln= Eu, Gd) at a loading of 0.6-0.7 mmol g-1. The hybrid materials were characterized by powder X-ray diffraction, IR and Raman ...
The photoluminescence features of Eu(3+)-, Tb(3+)-, Tb(3+)/Eu(3+)-alginate aerogel (hydrogel and ... more The photoluminescence features of Eu(3+)-, Tb(3+)-, Tb(3+)/Eu(3+)-alginate aerogel (hydrogel and alcogel) and Eu(3+)-alginate xerogel hybrids were investigated. The Eu(3+)-alginate aerogel and alcogel exhibit the highest (5)D0 quantum efficiencies (9.9 and 8.2%, respectively), while the hydrogel and xerogel have lower values (5.2 and 5.6%, respectively). The Tb(3+)/Eu(3+) hybrids are multiwavelength emitters in which the emission color can be tuned across the chromaticity diagram from the red toward the yellowish-green spectral regions, crossing the white area by selecting the excitation wavelength.
Page 1. Terbiumpolyoxotungstate Anions as Building Units to fabricate Nanostructured Films Filipa... more Page 1. Terbiumpolyoxotungstate Anions as Building Units to fabricate Nanostructured Films Filipa L. Sousa 1,a , Paula CR Soares-Santos 2,b , Helena IS Nogueira 2,c , Rute A. Sá Ferreira 3,d , Ana MV Cavaleiro 2,e , Luís D. Carlos 3,f , Tito Trindade 2,g ...
... PL, and excitation, PLE, spectra and time-resolved measurements were detected between 10 K an... more ... PL, and excitation, PLE, spectra and time-resolved measurements were detected between 10 K and RT on a modular double grating excitation spectrofluorimeter with a TRIAX 320 emission monochromator (Fluorolog-3, Jobin Yvon-Spex) coupled ... Bantignies, P. Dieudonné, JL. ...
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