LB films of 2-n-heptadecanoylbenzoic-rare earth and their luminescence properties

Several ultrathin luminescent Langmuir-Blodgett (LB) films have been prepared by using the subphase containing the rare earth ions (Eu3+, Tb3-). The effect of the rare earth ions on the monolayer of 2-n-heptadecanoylbenzoic acid (HBA) was investigated. IR and UV spectra showed the rare earth ions were bound to the carboxylic acid head groups and the coordination took place between the polar head group and the rare earth ions. The layer structure of the LB films was demonstrated by low-angle X-ray diffraction. UV absorbance intensity increases linearly with the number of LB films layers, which indicate that the LB films are homogeneously deposited. The LB films can give off strong fluorescence. and the signal can be detected from a single layer. The characteristic luminescence behaviors of LB films have been discussed compared with those of the complexes.

Synthesis, structure and luminescent properties of a new praseodymium(III) complex with beta-diketone

A new tetrakis praseodymium(tu) complex Pr(TFNB)(3)Phen has been synthesized, in which TFNB is 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione and Phen is 1,10-phenanthroline. Its crystal structure and luminescent spectra were successfully determined and investigated. The typical antenna effect existing in the luminescence of Pr(TFNB)(3)Phen was revealed by the study of the UV-Vis absorption spectra of ligands and the excitation spectrum of Pr(TFNB)(3)Phen.

Luminescent self-assembled thin films based on rare earth-heteropolytungstate

earth (Eu3+, Dy3+)-heteropolytungstate thin films were fabricated by self-assembly method successfully. The thin films give off strong fluorescence, which can be observed by eyes upon UV irradiation. The characteristic emission behaviors of the rare earth ions in self-assembled thin film were investigated compared with those of the corresponding solids. It is noticed that the intensity ratio between D-5(0) --> F-7(2) and D-5(0) --> F-7(1) of Eu3+ and the intensity ratio between F-4(9/2) --> H-6(13/2) and F-4(9/2) --> H-6(15/2) of Dy3+ in the self-assembled films are different from those of the corresponding solids. Furthermore, the self-assembled films present shorter fluorescence lifetimes than the corresponding solids. The reasons for these results have been discussed.

Langmuir-Blodgett films based on europium-substituted heteropolytungstate and their luminescence properties

Several new hybrid organic-inorganic Langmuir-Blodgett (LB) films containing europium-substituted hetero-polytungstate Eu (XW11O39)(2)''(-) (X=Ge, Si, B) were successfully obtained using LB technique. When the heteropolytungstate anions are dissolved in the subphase, dimethyldioctadecylammonium bromide compression isotherms have been modified, which shows that the polyanions interact with the monolayer. Y-type LB films were obtained from the systems. Low-angle X-ray has shown that these LB films have well-defined lamella. The LB films were characterized by luminescence spectra and the characteristic luminescence behavior for europium-substituted heteropolytungstate complexes and their LB films were discussed. The results of excitation spectra indicate that the energy could be effectively transferred from ligands to the Eu3+ ions in the LB films and the luminescence efficiency could be greatly increased. The results of luminescence spectra indicate that the formations of hybrid organic-inorganic LB films have a great effect on the luminescence of europium-substituted heteropolytungstate. The lifetime shortening was observed in LB films.

Preparation and characterization of a layered transparent luminescent thin film of silica-CTAB-Tb(acac)(3) composite with mesostructure

A layered luminescent mesostructured thin film of silica-CTAB-Tb(acac)(3) composite has been synthesized by a dip-coating process through an in situ sol-gel method. The terbium (Tb3+) ion and beta-diketone organic ligand acetylacetone (acac) were introduced into the precursor solution, respectively. The as-synthesized composite film was transparent, colorless and possessed a layered structure. After the composite film was dried at 50 degreesC for a few minutes Tb(acac)(3) complex was synthesized in the mesostructured thin film, which can be indicated by the luminescence of the composite film under the UV lamp. The properties of the samples were characterized by XRD, absorption, Fourier transform infrared spectroscopy, and luminescent spectra.

Red light-emitting diodes based on rare earth complex Eu (TTA)(4)C5H5NC16H33

A thin film electroluminescence cell with the structure of ITO/PPV/PVK:Eu(TTA)(4)C5H5NC16H33:PBD/Alq(3)/Al has been fabricated. Red emission with a very sharp spectral band at 614nm was observed and a maximum luminance of 20cd . m(-2) at 36V was obtained from the spin-coated device. The full width at half maximum of luminescent spectrum is less than 10nm.

Luminescence properties of lanthanide complexes doped in hybrid material from tetraethoxysilane and 3-glycidyioxyropyl-trimethoxysilane

Hybrid materials, containing in-situ synthesized lanthanide complexes with intense green light, have been prepared via sol-gel process. The luminescence properties and the decay times of as-synthesized samples were investigated. The excitation spectrum of the samples indicates the formation of complexes between terbium (III) and P-Sulfosalicylic acid. The hybrid materials that contain in-situ synthesized terbium complexes exhibit the characteristic emission bands of the rare earth ions. In addition, the effect of concentration of terbium on the luminescence properties as well as the thermal stability were also studied.

Preparation and luminescence properties of hybrid materials containing europium(III) complexes covalently bonded to a silica matrix

A new kind of luminescent organic-inorganic hybrid material (denoted Hybrid I) consisting of europium 1,10-phenanthroline complexes covalently attached to a silica-based network was prepared by a sol-gel process. 1,10-Phenanthroline grafted to 3-(triethoxysilyl)propyl isocyanate was used as one of the precursors for the preparation of an organic-inorganic hybrid materials. For comparison purposes, the hybrid material (denoted Hybrid II) in which phenanthroline was not grafted onto the silica backbone of the frameworks was also prepared. Elemental analysis; NMR, FT-IR, UV/vis absorption, and luminescence spectroscopies, and luminescence decay analysis were used to characterize the obtained hybrid materials. It is shown that the homogeneity of Hybrid I is superior to that of Hybrid II, and a higher concentration europium can be incorporated into Hybrid I than Hybrid II. Excitation at the ligand absorption wavelength (283 nm) resulted in the strong emission of the Eu3+ D-5(0)-F-7(J) (J = 0-4) transition lines as a result of the efficient energy transfer from the ligands to the EU3+ in Hybrid I. The number of water molecules coordinated to the europium ion was estimated, and the structure of the as-synthesized Hybrid I was predicted on the basis of the experimental results.

Effective energy transfer and luminescence of LB films based on europium-substituted heteropolytungstate

The europium-substituted heteropolytungstate K13Eu(SiW11O39)(2) was successfully assembled into two lipids by LB technique for the first time. X-ray diffraction has shown a well defined lamellar for the LB films. The LB films have been characterized by fluorescence spectra and the characteristic luminescence behaviors were discussed. The ligand-metal charge transfer band could be observed in the spectra of the LB films, which could not be found in that of heteropolytungstate solid. The results of fluorescence spectra indicate the energy could be effectively transferred from ligands to the Eu3+ ions in the LB films and the luminescence efficiency was increased greatly. The influences of various lipids on the luminescence of polyoxometalates were investigated. The various interactions between monolayer and polyanions have different effect on the luminescence properties of europium-substituted heteropolytungstate.

A novel way to enhance electroluminescence performance based on soluble binary and ternary europium 1,1,1-trifluoroacetylacetonate

Five rare earth complexes (Gd(acae)(3), Gd(TFacaC)(3), Eu(acaC)(3), Eu(TFacaC)(3) and Eu(TFacaC)(3)bipy; acac, acetylacetone; TFacac, 1,1,1-trifluoroacetylacetone; bipy, 2,2'-bipyridyl) were synthesized. By comparing the phosphorescence spectra of Gd(acac)(3) and Gd(TFacac)(3) the effect of the replacement of hydrogen by fluorine was examined. Organic light-emitting devices (OLEDs) based on the corresponding europium complexes as emissive layers were also fabricated by the spin-coating method. The triple-layer-type device with the structure glass substrate/ITO (indium-tin oxide)/PVK [poly(N-vinylcarbazole)]/(PVKEu)-Eu-.(TFacac)(3)bipy:PBD[2-(4-bibipyyl)-5-(4-t-butylbipyl-1,3,4-oxadiazole)]/PBD/Al (aluminum) exhibits a brighter red luminescence than those devices with Eu(acac)(3) and Eu(TFacac)(3) complexes as emissive centers upon applying a d.c. voltage.

Electroluminescence based on a beta-diketonate ternary samarium complex

The triplet energy state of the HTH [HTH: 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl) hexane-1,3-dione] ligand was measured to be 20 400 cm(-1), which indicated that Sm(HTH)(3) phen (phen: 1,10-phenanthroline) is a good complex to produce strong PL intensity and high fluorescence yield. Electroluminescent (EL) devices using the Sm( HTH) 3 phen complex as the emissive center were fabricated by vapor deposition and spin-coating methods. The relative intensity of the EL spectra changed compared to the photoluminescence (PL) spectrum, which suggested that the luminescence mechanisms of PL and EL have differences. A luminance of 9 cd m(-2) and a higher brightness of 21 cd m(-2) were obtained from the devices ITO/TPD (40 nm)/ Sm( HTH)(3) phen (50 nm)/ PBD (30 nm)/ Al (200 nm) and ITO/PVK (40 nm)/ PVK : Sm( HTH)(3) phen (2.5 wt%, 50 nm)/ PBD (30 nm)/ Al (200 nm), respectively.

Green electroluminescence generated from the thin film based on a soluble lanthanide complex

Electroluminescent (EL) devices based on a soluble complex Tb(MDP)(3) [Tris-(monododecyl phthalate)Terbium] doped with poly (N-vinylcarbazole) (PVK), (2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole) (PBD) were fabricated. The device structures of ITO/PVK/PVK:PBD:Tb(MDp)(2)/Aiq(3)/Al and ITO/PVK:PBD:Tb(MDP)(3)/Alq(3)/Al were employed. The Tb(MDP), as emissive layer was spin-coated. The EL cell exhibited characteristic emission of terbium ion. (C) 2000 Elsevier Science S.A. All rights reserved.

Preparation and luminescence properties of lanthanide complexes and their silica-based composites

Binary complexes of europium and terbium with N-propyl-4-carboxyphthalimide (NP) were prepared and characterized. The luminescence behaviors of the lanthanide complexes as well as their doped silica-based composites were investigated by fluorescence spectra. The results indicated that the lanthanide complexes showed fewer emission lines and slightly lower intensities in silica matrix than that of corresponding pure complexes. The lifetimes of the lanthanide complexes became longer when they were incorporated in silica matrix. (C) 2001 Elsevier Science B.V. All rights reserved.

Spectroscopic study of the photophysical properties of rare earth ions encapsulated: Water soluble functional calixresorcin[4]arene

A novel macrocyclic compound-water soluble functional calixresorcin[4]arenes-tetra para sulfo-phenylmethyl-calixresorcin[4]are was synthesized for the first time. The photophysical properties of terbium and europium ions encapsulated in the macrocyclic ligand were studied in detail. The triplet state energy of the calixresorcin[4]arene was determined to be 24400 cm(-1) by the low temperature phosphorescence spectrum and it was found that it can sensitize both terbium ion and europium ion. The possible energy transfer process between the functional calixresorcin[4]arene and the encapsulated Tb3+ and Eu3+ was discussed. The luminescence quantum efficiency of Tb3+- calixresorcin[4]arene was calculated.

Preparation and characterization of ternary europium complex-doped thin sol-gel hybrid film by fluorescence spectroscopy

Ternary europium complex with dibenzoylmethane (DBM) and 1,10-phenanthroline (phen) was in-situ synthesized in thin SiO2/polyvinyl butyral (PVB) hybrid films by a two-step sol-gel process and characterized by;means of fluorescence spectroscopy. The luminescence spectra, fluorescence lifetimes and photostability were all investigated. The results showed that the hybrid films exhibited the characteristic emission bands of the Central rare earth Eu3+. In addition, Eu3+ presented longer fluorescence lifetime than in an ethanol solution and the complex had a higher photostability in the hybrid film than in the PVB film containing the corresponding pure complex.