Photochemical behavior of polymer complexes based on Eu(III) acrylato(bisdibenzoylmethanate)

The photochemical behavior of monomer and polymer complexes of Eu³⁺ that are based on dibenzoylmethane and acrylic acid has been studied. It has been shown that these complexes differ from their low-molecular-mass analogs by properties: in the course of photolysis, the intensity of luminescence of the studied Eu³⁺ complexes increases by a factor of 1.3 to 2.5. The mechanism describind the effect of the composition of polymer formulation on the rate of photodegradation is discussed.     

Crystal structure of boron difluoride 3-phenylthiopentane-2,4-dionate. π stacking interactions and luminescence of boron difluoride acetyl acetonates

The crystal structure of boron difluoride 3-phenylthiopentane-2,4-dionate was determined. The relationship between the structure and luminescent properties is traced in the series of boron difluoride acetyl acetonates (acetyl acetonate, phenylacetyl acetonate, and phenylthioacetyl acetonate). The presence of the π stacking interactions in boron difluoride phenylthioacetyl acetonate crystals leads to increased intensity and bathochromic shift of the fluorescence band.     

Crystal structure and triboluminescence of the [Tb(BTFA)2(NO3)(TPPO)2] complex

The crystal structure of the [Tb(BTFA)₂(NO₃)(TPPO)₂] complex (TPPO is triphenylphosphine oxide, BTFA is benzoyltrifluoracetone), which exhibits strong triboluminescence, has been established by X-ray crystallography. The crystals are triclinic: a = 11.668(3) Å, b = 11.700(3) Å, c = 12.512(3) Å, α = 65.161(4°), β = 79.120(4)°, γ = 61.860(4)°, space group P1, Z = 1. The central terbium(III) atom coordinates two oxygen atoms from two triphenylphosphine oxide molecules (Tb-O, 2.264(3) and 2.273(3) Å), two oxygen atoms from the nitrate group (Tb-O, 2.460(3) and 2.476(3) Å), and four oxygen atoms from two benzoyltrifluoroacetonate groups (Tb-O, 2.329(3), 2.399(3), 2.351(3), and 2.367(3) Å). The coordination polyhedron of the Tb(III) atom is a distorted dodecahedron. The photoluminescence and triboluminescence spectra of the [Tb(BTFA)₂(NO₃)(TPPO)₂] complex are identical and caused by the f-f luminescence of Tb³⁺.     

Optical properties of a new photorecording polymer based on 2,2-difluoro-4-(9-anthracyl)-6-methyl-1,3,2-dioxaborine

The optical properties of a new photorecording polymer based on 2,2-difluoro-4-(9-anthracyl)-6-methyl-1,3,2-dioxaborine have been investigated. This material is found to change its absorption coefficient and refractive index in the visible range under illumination with a wavelength λ = 405.9 nm. This circumstance makes it possible to record static holograms with a spatial frequency up to 2500 lines/mm, a diffraction efficiency above 60%, and a lifetime more than 6 months. A dynamic change in the effective refractive index of this material under 405.9-nm irradiation is found, due to which one can form control optical elements of the light-light type with a modulation frequency up to 50 Hz in it.     

Luminescence and magnetic properties of europium(III) carboxylatodibenzoylmethanates

This paper reports on the results of an investigation of the luminescence and magnetic properties of europium(III) carboxylates, which are determined by the structure of the Stark and Zeeman sublevels. It has been established that the energy splittings λ_lum between the ⁷ F ₀ ground level and the ⁷ F ₁ term in the luminescence spectra of these compounds well correlate with the energy splittings λ_magn obtained from magnetochemical measurements.     

Columinescence effect in macromolecular complexes of Eu(III) and Tb(III)

The effect of Y(III) and Gd(III) coactivator ions on the intensity of Eu(III) and Tb(III) luminescence in monomer and polymer mixed-metal complexes was studied. Isomorphic replacement of Eu(III) and Tb(III) ions by Y(III) and Gd(III) ions in macromolecular complexes led to sensitization of Eu(III) and Tb(III) ion luminescence. A mechanism of columinescence was suggested. It involves a charge transfer and the ligand orbitals and the vacant orbitals of Eu(III) and Tb(III) ions and coactivators.     

Crystal structure,luminescent and thermochromic properties of bis(tetraethylammonium) hexachlorotellurate(IV)

The crystal structure of (C₂H₅)₄N)₂TeCl₆ was determined by X-ray diffraction (a = 14.130(2) Å, b = 14.547(2)Å, c = 13.296(2)Å, β= 90.356(3)°; space group C2/c, Z = 4, ρ_(calcd) = 1.387 g/cm³). The crystal structure is composed of the [TeCl₆]^2? anions and tetraethylammonium cations ((C₂H₅)₄N)⁺. The electronic and geometric aspects that determine the spectral luminescence and thermochromic properties of the complex are discussed.     

Luminescence and magnetic properties of mixed-ligand europium trifluoroacetates

The luminescence and magnetic properties of mixed-ligand europium trifluoroacetates with nitrogen- and phosphorus-containing neutral ligands [Eu(TFA)₃ · 3H₂O]₂ and Eu(TFA)₃ · 2D · nH₂O were studied (here TFA is the trifluoroacetic acid anion, and D is Phen (1,10-phenanthroline), n = 1; DMF (dimethylformamide), n = 1; or TPPO (triphenylphosphine oxide), n = 3). The molar magnetic susceptibility increased in the series of complex compounds Eu(TFA)₃ · 2Phen · H₂O < [Eu(TFA)₃ · 3H₂O]₂ < Eu(TFA)₃ · 2DMF · H₂O < Eu(TFA)₃ · 2TPPO · 3H₂O. Correlations were found between the luminescent and magnetic characteristics of the complex compounds.     

Photostability of rare-earth element hexafluoroacetylacetonates

Measurements have been made of the quantum yields in photodecomposition of adducts of lanthanide hexafluoroacetylacetonates in hexane, with various excitation energies. The photoreactivity of luminescing complexes of Eu³⁺ and Sm³⁺ is much lower than the reactivity of the nonluminescing complexes of La³⁺ and Gd³⁺. The photoreactivity of the complexes is lower when oxygen is present.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1975–1978, September, 1989.