Promising Light-conversion Molecular Device Research Articles

A series of highly quantum efficiency PMMA luminescent films doped with Eu-complex as promising light-conversion molecular devices

In this paper, a series of Eu/PMMA and Eu/PMMA/SiO2 luminescent films have been designed, fabricated and characterized. Thermo-gravimetric analysis and photo-luminescence results indicated the Eu-complex precursor was successfully immobilized in PMMA matrix through the interaction between the Eu-complex and the –C=O groups of the PMMA matrix. The emission spectra of the Eu-complex and Eu/PMMA films recorded at 25 °C exhibited the characteristic bands arising from the 5D0/7FJ. The fact that the quantum efficiencies (η) of the doped film increased significantly indicated that PMMA matrix acted as an efficient co-sensitizer for Eu3+ ions luminescent center, and therefore enhanced the η of the emitter 5D0 level. Especially, with the doping nano-SiO2 into Eu/PMMA-5 % system, the T d-5 % of Eu/PMMA/SiO2 has obviously improved. Due to the carrying effect of nano-SiO2 and interaction between –C=O of PMMA chain and Eu3+ ions, the η of Eu/PMMA/SiO2 films have been greatly enhanced. To the best of our knowledge, the η of Eu/PMMA/SiO2-3 % film (78.57 %) is found to be the highest so far reported in the literature. These Eu/PMMA/SiO2 luminescent films show excellent luminescent properties and therefore have potential applications in light-conversion molecular device.

Mono- and dinuclear europium(III) complexes with thenoyltrifluoroacetone and 1,10-phenanthroline-5,6-dione

The N,N′-coordinated mononuclear complex Eu(TTA)3(pdn), prepared by treating 1,10-phenanthroline-5,6-dione (pdn) with Eu(TTA)3(H2O)2 (HTTA = 2-thenoyltrifluoroacetone), may be used as a benzoquinone-like ligand through the oxygen donor atoms in reaction with an additional Eu(TTA)3(H2O)2 precursor to give the dinuclear complex Eu2(TTA)6(pdn). Both the mono- and dinuclear complexes were characterized by elemental analysis, IR, TG, MS, and 1H NMR spectra. The results indicated that they both exhibited a characteristic red emission peak at 616 nm, corresponding to the 5D0 → 7F2 transition of Eu(III) ions under UV excitation. Compared with the mononuclear complex, the dinuclear complex presented better thermal stability and stronger luminescence, which makes it a promising light-conversion molecular device. .

Photophysical properties and Judd-Ofelt analysis of a europium complex with 5-amino-1,10-phenanthroline

A europium (III) complex with 5-amino-1,10-phenanthroline and 2-thenoyltrifluoroacetone, Eu(TTA) 3(phenNH 2), was synthesized. Its photophysical properties were studied in detail using UV, luminescence spectra and lifetime measurements. The complex shows a long 5D 0 lifetime (588 μs) and a remarkable luminescence quantum yield (40.95%) at room temperature, which makes it not only a promising light-conversion molecular device but also an excellent luminescent polymer precursor. Moreover, the applicability of the well-known Judd-Ofelt theory to the emissive properties of Eu 3+ complexes is also investigated.

Synthesis and characterization of a Eu-containing polymer precursor featuring thenoyltrifluoroacetone and 5-acrylamido-1,10-phenanthroline

A polymerizable ligand, 5-acrylamido-1,10-phenanthroline ( L), was synthesized. Its Eu(III) complex with 2-thenoyltrifluoroacetone (HTTA) was prepared and characterized by elemental analysis, IR, MS, and 1H NMR spectra. The photophysical properties of the complex were studied in detail by using UV, luminescence spectra, luminescence lifetime and quantum yield. The complex shows a remarkable luminescence quantum yield at room temperature (40.1%) upon ligand excitation and a long 5D 0 lifetime (590 μs), which makes it not only a promising light-conversion molecular device but also an excellent luminescent polymer precursor.

Design, synthesis and characterization of a highly luminescent Eu-complex monomer featuring thenoyltrifluoroacetone and 5-acryloxyethoxymethyl-8-hydroxyquinoline

A multi-functional ligand, 5-acryloxyethoxymethyl-8-hydroxyquinoline (Hamq), was synthesized, which contained a polymerizable C=C double bond for the copolymerization with other vinyl monomers and acted as photon antenna able to transfer energy to Eu 3+ ions effectively. The triplet state energy of Hamq was determined to be 22,370 cm −1 via the phosphorescence spectra of Hamq and its gadolinium complex. The title complex monomer Eu(tta) 2(amq) was prepared by coordination reaction of Hamq with europium isopropoxide and 2-thenoyltrifluoroacetone (Htta) in dry organic solvents under argon atmosphere and characterized by elemental analysis and IR spectrum. The photophysical properties of the complex were studied in detail with UV–vis, luminescence spectra, luminescence lifetime and quantum yield. The complex exhibited nearly monochromatic red emission at 612 nm, a remarkable luminescence quantum yield at room temperature (30.6%) upon ligand excitation and a long 5D 0 lifetime (389 μs), which indicated that the ligand Hamq could sensitize the luminescence of Eu(III) ion efficiently in Eu(tta) 2(amq), resulting in a strong luminescence of its copolymer poly[MMA- co-Eu(TTA) 2(amq)] under UV excitation. The excellent luminescence properties of the complex made it not only a promising light-conversion molecular device but also an excellent luminescent monomer.

4,4,5,5,5-Pentafluoro-1-(9H-fluoren-2-yl)-1,3-pentanedione complex of Eu3+ with 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene oxide as a promising light-conversion molecular device

A novel beta-diketone ligand, 4,4,5,5,5-pentafluoro-1-(9H-fluoren-2-yl)-1,3-pentanedione (Hpffpd), which contains a polyfluorinated alkyl group, as well as a long conjugated fluorene unit, and a chelate phosphine oxide ligand, 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene oxide (DDXPO) were synthesized and utilized for the synthesis of two new europium complexes [Eu(pffpd)3(C2H5OH)(H2O)] 1 and [Eu(pffpd)3(DDXPO)] 2. For comparison, the [Eu(pffpd)3(DPEPO)] 3 complex was also synthesized involving a known chelate phosphine oxide, bis(2-(diphenylphosphino)phenyl) ether oxide (DPEPO). The synthesized complexes have been characterized by various spectroscopic techniques and their solid-state photophysical properties were investigated. The single-crystal X-ray diffraction analyses of 2 and 3 revealed that these complexes are mononuclear, and that the central Eu3+ ion is surrounded by eight oxygen atoms, six of which are from the three bidentate fluorinated beta-diketonates, and the other two oxygen atoms from the chelate phosphine oxide. The coordination polyhedra can be described as distorted square antiprism. Compound 2 has a solid-state photoluminescence quantum yield of 48%, which is about two times higher than that of compound 3 (28%). This may be due to the fact that DDXPO in 1 has the mezzo first triplet excited state energy level (T1) between the first singlet excited energy level (S1) and T1 of Hpffpd, which may support one more additional energy transfer from the T1 energy level of DDXPO to that of Hpffpd, and consequently improves the energy transfer in the Eu3+ complex. Furthermore, DDXPO (average Eu-O = 2.34 A) in complex 2 coordinates more strongly with the central Eu3+ as compared to DPEPO in complex 3 (average Eu-O = 2.38 A) which can improve the energy transfer between the ligands and central metal ion, and consequently enhances the photoluminescence efficiency of the corresponding Eu3+ complex.

3-Phenyl-4-acyl-5-isoxazolonate complex of Tb3+ doped into poly-β-hydroxybutyrate matrix as a promising light-conversion molecular device

A novel class of efficient antenna complexes of Tb3+ based on the use of 3-phenyl-4-acyl-5-isoxazolone ligands has been designed, synthesized, characterized and their photophysical properties evaluated . The new heterocyclic β-diketonate complexes of Tb3+ exhibit high green luminescence efficiency in the solid state with quantum yields between 59–72%. Furthermore in this work, the synthesis, characterization and luminescent properties of poly-β-hydroxybutyrate (PHB) polymer films doped with Tb3+-3-phenyl-4-acyl-5-isoxazolonate complexes at 5, 10, 15 and 20% (mass) are reported. The fact that the luminescent efficiency of doped films is enhanced (quantum yields between 74–86%) compared with precursor samples revealed that the polymer matrix acts as a co-sensitizer for Tb3+centers. The luminescence intensity decreases, however, with increasing precursor concentration in the doped PHB to greater than 15% where a saturation effect is observed, indicating that changes in the polymer matrix improve the absorption properties of the film, consequently quenching the luminescent effect. Synthesized luminescent polymers containing Tb3+-hetrocyclic β-diketonate complexes showed promising photoluminescence efficiency for applications to polymer light-emitting diodes and active polymer optical fibers.

3-Phenyl-4-aroyl-5-isoxazolonate complexes of Tb3+ as promising light-conversion molecular devices

New tris(3-phenyl-4-aroyl-5-isoxazolonate)terbium(III) complexes have been synthesized and characterized by various spectroscopic techniques. Due to an efficient energy transfer from the heterocyclic β-diketonate ligand to the central Tb3+, these complexes show a strong emission corresponding to Tb3+5D4–7FJ (J=6, 5, 4, 3) transitions, with 5D4–7F5 (545nm) green emission as the most prominent one. The overall quantum yields and luminescent lifetimes of these complexes were found to be promising as compared to previously reported terbium-1-phenyl-3-methyl-4-acyl-5-pyrazolonate complexes.

Synthesis and Kinetic Study by Ozawa Method of the Thermal Decomposition of Complexes Ln(thd)<sub>3</sub>phen

Recently, highly luminescent lanthanide complexes with mixed ligands such as and β-diketone and two herobiaryl ligands have been synthesized and suggested as promising light-conversion molecular devices as described by several authors. The synthesis, luminescence, quantum yields, spectroscopic characteristics, structure, among others properties of these complexes, including the possibility of production thin film films from these materials have been discussed, but little is known about their thermal decomposition kinetics. In this work we report the determination of kinetic parameters of thermal decomposition of the complexes Gd(thd)3phen and Er(thd)3phen (thd=2,2,6,6-tetramethyl-3,5- heptanodione; phen=1,10-phenantroline) using the method proposed by Ozawa (1965). The kinetic parameters obtained for activation energy were: 90 and 87 kJ.mol-1, the values of frequency factor were: 2.3x107 and 2.0x107 s-1 for Gd(thd)3phen and Er(thd)3phen, respectively. On the kinetic energy of the complexes, we notice the following order in thermal stability: Gd(thd)3phen < Er(thd)3phen.

3-Phenyl-4-benzoyl-5-isoxazolonate Complex of Eu3+ with Tri-n-octylphosphine Oxide as a Promising Light-Conversion Molecular Device

Three new europium complexes, [Eu(PBI)3.3H2O] (1), [Eu(PBI)3.2TOPO] (2), and [Eu(PBI)3.2TPPO.H2O] (3) (where HPBI, TOPO, and TPPO stand for 3-phenyl-4-benzoyl-5-isoxazolone, tri-n-octylphosphine oxide, and triphenylphosphine oxide, respectively), with different neutral ligands were synthesized and characterized by elemental analysis, Fourier transform infrared, (1)H NMR, thermogravimetric analysis, and photoluminescence (PL) spectroscopy. The coordination geometries of the complexes were calculated using the Sparkle/AM1 (Sparkle Model for the Calculation of Lanthanide Complexes within the Austin Model 1) model. The ligand-Eu3+ energy-transfer rates were calculated in terms of a model of the intramolecular energy-transfer process in lanthanide coordination compounds reported in the literature. The room-temperature PL spectra of the europium(III) complexes are composed of the typical Eu3+ red emission, assigned to transitions between the first excited state (5D0) and the multiplet (7F(0-4)). On the basis of emission spectra and lifetimes of the 5D0-emitting level, the emission quantum efficiency (eta) was determined. The results clearly show that the substitution of water molecules by TOPO leads to greatly enhanced quantum efficiency (i.e., 26% vs 92%) and longer 5D0 lifetimes (250 vs 1160 micros). This can be ascribed to a more efficient ligand-to-metal energy transfer and a less nonradiative 5D0 relaxation process. Judd-Ofelt intensity parameters (Omega2 and Omega4) were determined from the emission spectra for the Eu3+ ion based on the 5D0 --> 7F2 and 5D0 --> 7F4 electronic transitions, respectively, and the 5D0 --> 7F1 magnetic-dipole-allowed transition was taken as the reference. A point to be noted in these results is the relatively high value of the Omega2 intensity parameter for all of the complexes. This may be interpreted as being a consequence of the hypersensitive behavior of the 5D0 --> 7F2 transition. The dynamic coupling mechanism is, therefore, dominant, indicating that the Eu3+ ion is in a highly polarizable chemical environment.

Synthesis and spectroscopic behavior of highly luminescent Eu3+–dibenzoylmethanate (DBM) complexes with sulfoxide ligands

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.

Europium(III) mixed complexes with β-diketones and o-phenanthroline-N-oxide as promising light-conversion molecular devices

Download options Please wait... Article information DOI https://doi.org/10.1039/CC9960001199 Article type Paper Download Citation Chem. Commun., 1996, 1199-1200 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Europium(III) mixed complexes with β-diketones and o-phenanthroline-N-oxide as promising light-conversion molecular devices C. De Mello Donegá, S. A. Junior and G. F. De Sá, Chem. Commun., 1996, 1199 DOI: 10.1039/CC9960001199 To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Celso De Mello Donegá Severino A. Junior Gilberto F. De Sá