Luminescence properties of LB films based on heteropolytungstate of rare earth

In this work, the LB films based on heteropolytungstate of Dy and Sm have been prepared. The X-ray diffraction shows the LB films have a highly ordered lamella structure. The luminescence characteristics of the LB films were studied. The charge transfer bands of LB films are in higher energies than those of the corresponding solids. It is noticed that the yellow to blue intensity ratio (Y:B) of Dy3+ in the LB films is different from that of the solid. The differences in the spectra show that the Dy3+ site symmetry in LB film was changed due to the interaction between the surfactant and the polyanions. The differences could also be found in the luminescence spectra of the LB films of Sm complex.

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.

Preparation and luminescence properties of LB films based on 4-hexadecyloxybenzoic terbium

LB films of 4-hexadecyloxybenzoic-terbium by using the subphase containing Tb3+ were prepared. The monolayer behavior of 4-hexadecyloxybenzoic acid (HOBA) on the subphase containing rare earth ions was studied. IR and UV spectra show that the rare earth ions were bound to carboxylic acid head groups and the coordination took place between the polar head group and the rare earth ions. The luminescence spectra show that the LB films have the fine luminescence properties, and the LB films emit strong luminescence under UV light irradiation.

Characterization of the microstructure of biaxially oriented polypropylene using preparative temperature-rising elution fractionation

Two commercial biaxially oriented polypropylene (BOPP) resins, resin A and resin B, having different processing properties, were fractionated by preparative temperature-rising elution fractionation (TREF). The TREF fractions were further characterized by gel permeation chromatography (GPC), gel permeation chromatography coupled with light scattering (GPC-LS), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC). GPC-LS did not find visible long-chain branching in either resin A or B. The results from TREF and DSC indicate that the fractional melting parameter f(T) may be used to predict the profile of the TREF cumulative weight distribution curve. GPC results show that the molecular weights of the fractions tend to increase with elution temperature. WAXD and DSC data show that the crystallinity of fractions does not increase monotonically with increase of elution temperature. There appears to be a maximum in the plot of crystallinity versus elution temperature. The high-speed BOPP resin A has a lower isotacticity but a homogeneous isotacticity distribution and a higher molecular weight but a broader molecular weight distribution than resin B.

Ring-opening polymerization of epsilon-caprolactone and L-lactide using organic amino calcium catalyst

Poly (6-caprolactone) (PCL) and poly (L-lactide) (PLA) were prepared by ring-opening Polymerization catalyzed by organic amino calcium catalysts (Ca/PO and Ca/EO) which were prepared by reacting calcium ammoniate Ca(NH3)(6) with propylene oxide and ethylene oxide, respectively. The catalysts exhibited high activity and the ring-opening polymerization behaved a quasi-living characteristic. Based on the Fr-IR spectra and the calcium contents of the catalysts, and based on the H-1 NMR end-group analysis of the low molecular weight PCL prepared using catalysts Ca/PO and Ca/EO, it was proposed that the catalysts have the structure of NH2-Ca-O-CH(CH3)(2) and NH2-CaO-CH2CH3 for Ca/PO and Ca/EO, respectively. The ring-opening polymerization of CL and LA follows a coordination-insertion mechanism and the active site is the Ca-O bond.

Calculation of electrostatic energy H-e(fd) on 4f(N-1)5d configurations for heavy lanthanide ions

For the 4f(N-1)5d configuration the Coulomb interaction between f and d electrons was parameterized by F-k(fd) with K = 2, 4, and G(K)(fd) with K = 1, 3, 5. The spin-orbit interaction for 4f and 5d electrons can be parameterized by xi (f) and xi (d) respectively, which can be compounded into one lambda : lambda = axi (f) + bxi (d), where a and b are the corresponding coefficients. The energy expressions of H-e(fd) of the chief low-energy levels of 4f(N-) (1)5d configuration for heavy lanthanide ions were calculated and the corresponding spin-orbit parameters lambda were also given in LS coupling, which are profitable in analyzing the spectra of the heavy lanthanide ions.

Luminescent hybrid films obtained by covalent grafting of terbium complex to silica network

Luminescent hybrid thin films consisting of terbium complex covalently bonded to a silica-based network have been obtained in situ via a sol-gel approach. A new monomer, N-(4-benzoic acid-yl), N'-(propylthiethoxysilyl)urea (PABI), has been synthesized by grafting isocyanatopropyltriethoxysilane (ICPTES) to p-aminobenzoic acid and characterized by H-1 NMR IR and MS, The monomer acts as a ligand for Tb3+ ion and as a sol-gel precursor. Band emission front Tb3+ ion due to an efficient ligand-to-metal energy transfer was observed by UV excitation. The decay curves of Tb3+ in the hybrid films were measured. The energy difference between the triplet state energy of PABI and the D-5(4) level of Tb3+ ion falls in the exciting range to sensitize Tb3+ ion fluorescence.

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, photo and electroluminescence properties of novel rare earth aromatic carboxylates

Novel soluble rare earth aromatic carboxylates were prepared. The triplet energy level of organic ligand was measured. The photoluminescence properties of the Tb3+ and EU3+ aromatic carboxylates and lifetimes were investigated, which indicated that these rare earth complexes have high quantum efficiency. Because of their excellent solubility, polymer-doping rare earth carboxylates were fabricated as thin Films by spin-coating method and their luminescence properties were studied. Some rare earth organic light-emitting diodes were successfully fabricated which performed high pure color. The maximum luminance of the device of ITO/PVK/PVK :Th (AS)(3)Phen: PBD/PBD/Al is 32 cd(.)m(-2) at 28 V.

Luminescence properties of rare earth-polyoxometalate thin film deposited by sol-gel process

The rare earth (Eu3+, Dy3+)-polyoxometalate thin films were fabricated on quartz plate by the sol-gel method. The thin films were demonstrated by the luminescence spectra. The thin films exhibit the characteristic emission bands of the rare-earth ions. It is noticed that the yellow to blue intensity ratio (Y:B) of Dy3+ and the red to orange ratio (R:O) of Eu3+ in the films are different from that of the corresponding solids. Furthermore, the thin films present shorter fluorescence lifetime than the pure complexes. The reasons that were responsible for these results were also discussed.

Hybrid luminescent films obtained by covalent anchoring terbium complex to silica-based network

New monomer N-(4-carboxyphenyl)-NL-(propyltriethoxysilyl)urea (1) which acts as both a ligand for Th3+ ion and a sol-gel precursor has been synthesized and characterized by H-1 NMR, and MS. Hybrid luminescent thin films consisting of organoterbium covalently bonded to a silica-based network have been obtained in situ via a sol-gel approach. Strong line emission of Tb3+ ion was observed from the hybrid luminescent films under UV excitation.

Crystal structure of a luminescent complex Sm(HTH)(3)Phen

The crystal structure of Sm(HTH)(3)Phen [HTH: 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)-1,3-hexanedione, Phen: 1,10-Phenanthroline] has been determined by single crystal X-ray diffraction and the coordination geometry of Sm atom is a dodecahedron. The complex can give the characteristic luminescence of Sm3+ upon UV excitation.

Luminescence properties of transparent hybrid thin film covalently linked with lanthanide complexes

Novel hybrid thin films covalently doped with Eu3+ (Tb3+) have been prepared via direct routes involving co-condensation of tetraethoxysilane and phen-Si in the presence of Eu3+ (Tb3+) by spin-casting and their luminescence properties have been investigated in detail. Lanthanide ions can be sensitized by anchored phenanthroline in hybrid thin films. Excitation at the ligand absorption wavelength (272 nm) resulted in the strong emission of the lanthanide ions i.e. Eu3+ D-5(0)-F-7(J) (J=0, 1, 2, 3, 4) emission lines and Tb3+ D-5(4)-F-7(J) (J = 6, 5, 4, 3) due to the energy transfer from the ligands to the lanthanide ions.