Lianshe Fu

Luminescent film with terbium-complex-bridged polysilsesquioxanes

A luminescent film with terbium-complex-bridged polysilsesquioxanes has been prepared by sol-gel processing of a new bifunctional monomer that combines the role of a sol-gel molecular precursor with a Tb3+ ion coordinate donor. The emission from Tb3+ ion due to ligand-to-metal energy transfer was observed by UV excitation.

Lanthanide complex/polymer composite optical resin with intense narrow band emission, high transparency and good mechanical performance

Novel composite resins possessing good luminescent properties have been synthesized through a free radical copolymerization of styrene, α-methylacrylic acid and the binary or ternary complexes of lanthanide ions (Eu3+ and Tb3+). These polymer-based composite resins not only possess good transparency and mechanical performance but also exhibit an intense narrow band emission of lanthanide complexes under UV excitation. We characterized the molecular structure, physical and mechanical performance, and luminescent properties of the composite resins. Spectra investigations indicate that α-methyl-acrylic acid act as both solubilizer and ligand. Photoluminescence measurements indicate that the lanthanide complexes show superior emission lines and higher intensities in the resin matrix than in the corresponding pure complex powders, which can be attributed to the restriction of molecular motion of complexes by the polymer chain networks and the exclusion of water molecules from the complex. We also found that the luminescence intensity decreased with increasing content of α-methylacrylic acid in the copolymer system. The lifetime of the lanthanide complexes also lengthened when they were incorporated in the polymer matrix. In addition, we found that the relationships between emission intensity and Tb (Eu) content exhibit some extent of concentration quenching.

Phenanthroline-functionalized MCM-41 doped with Europium ions

Abstract Organo-functionalized MCM-41 containing non-covalently linked 1,10-phenanthroline (denoted as Phen-MCM-41) was synthesized by template-directed co-condensation of tetraethoxysilane and the modified phenanthroline (denoted as Phen-Si). XRD, FTIR, UV/VIS spectroscopy as well as luminescence spectroscopy were employed to characterize Phen-MCM-41. No disintegration or loss of the Phen-Si during the solvent extraction procedure could be observed. When monitored by the ligand absorption wavelength (272 nm), the undoped MCM-41 produces a broad band emission centered at 450 nm, whereas europium (III) doped Phen-MCM-41displays the emission of the Eu 3+ , i.e., 5 D 0 → 7 F J ( J =0, 1, 2, 3, 4) transition lines due to the energy transfer from the ligands to Eu 3+ as well as a broad band emission centered at 442 nm.

Electroluminescence based on a β-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)3phen (phen: 1,10-phenanthroline) is a good complex to produce strong PL intensity and high fluorescence yield. Electroluminescent (EL) devices using the Sm(HTH)3phen 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)3phen (50 nm)/PBD (30 nm)/Al (200 nm) and ITO/PVK (40 nm)/PVK∶Sm(HTH)3phen (2.5 wt%, 50 nm)/PBD (30 nm)/Al (200 nm), respectively.

Incorporation of luminescent lanthanide complex inside the channels of organically modified mesoporous silica via template-ion exchange method

Luminescent lanthanide complex, Eu(phen)2Cl3·2H2O (Euphen, phen = 1,10-phenanthroline) has been incorporated inside the channels of mesoporous silica MCM-41 with its external surface modified by phenyltriethoxysilane (Ph-Si(OEt)3) via a simple template-ion exchange method. The passivation of active groups such as silanols in the external surface ensures that the ion exchange reaction occurs between the surfactant cations and the lanthanide complex ions inside the channels of the modified MCM-41. The passivation result is confirmed by 29Si MAS NMR spectroscopy. FT-IR demonstrates that the cationic surfactants are completely removed. XRD and N2 adsorption–desorption measurements are employed to characterize the mesostructure of Euphen-Ph-MCM-41. Luminescence and stability studies on the materials of Euphen and Euphen-Ph-MCM-41 show that the resultant hybrid material Euphen-Ph-MCM-41 exhibits the characteristic emission of Eu3+ ions under UV irradiation with higher 5D0 luminescence quantum efficiency, longer lifetime and better thermal stability than the corresponding pure complex Euphen. Moreover, the characterization results show that the local symmetry and the first coordination shell of Eu3+ ions are changed after the complex ions become incorporated into the MCM-41 channels and that a more symmetric environment is occupied by the Eu3+ ions in Euphen-Ph-MCM-41 than in Euphen. There is also a more efficient ligand-to-Eu(III) intramolecular energy transfer process in Euphen-Ph-MCM-41.

Luminescence characteristics of europium and terbium complexes with 1,10-phenanthroline in-situ synthesized in a silica matrix by a two-step sol-gel process

In-situ synthesis of europium and terbium complexes with 1,10-phenanthroline (phen) in silica matrix by a two-step sol-gel process has been proposed. The formation of europium and terbium complexes with phen in sol-gel derived silica gel were confirmed by the luminescence excitation spectra. The silica gels that contain in-situ synthesized europium and terbium complex exhibit the characteristic emission bands of the rare earth ions. Furthermore. the rare earth ions present longer fluorescence lifetimes than the comparable pure complex powder and the complexes dissolved in ethanol solutions. The luminescence properties of the silica gels codoped with europium (or terbium) and phen were also investigated with respect to the gels doped with europium (or terbium)

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.

Eu3+-Based Bridged Silsesquioxanes for Transparent Luminescent Solar Concentrators

The sol-gel preparation of a bridged silsesquioxane containing europium(III) salts and 2-thenoyltrifluoroacetone has been achieved from a new ethane tetracarboxamide-based organosilane. Free-standing films with thicknesses up to 440 μm and maximum absolute quantum yield (q) of 0.34 ± 0.03 (excitation at 320 nm) were prepared by the drop cast method, while thin films (∼200-400 nm) spin-coated on glass substrates led to highly luminescent coatings with q = 0.60 ± 0.02 (excitation at 345 nm). The thin films were tested as planar luminescent solar concentrators and the optimized device displays an optical conversion efficiency of 12.3% in the absorbing spectral region of the active layer (300-380 nm).

Preformed sol-gel synthesis and characterization of YAlO3

The synthesis of YAlO3 is described from commercially-available yttria and alumina preformed sols which have nanometer particle-size ranges. The products have been characterized by X-ray diffraction (XRD), diffuse reflectance infrared Fourier transform (DRIFT) spectra, thermogravimetry—derivative thermogravimetry—differential thermal analysis (TG-DTG-DTA), scanning electron microscopy (SEM) as well as CHN-analysis, and are similar to those prepared by the alkoxide, nitrate and citrate routes. The proposed method is a simple, cheap and rapid synthetic route.

Novel, covalently bonded hybrid materials of europium (terbium) complexes with silica

New kinds of hybrid materials containing covalently bonded Eu3+ (Tb3+) bipyridine complexes in a silica network have been prepared and their luminescence properties reported.