Rise of photoluminescence in the photolysis of EuIII complexes with copolymers of acrylic acid and butyl methacrylate

The luminescence and photochemical properties of Eu^III complexes with copolymers of acrylic acid and butyl methacrylate have been studied by luminescence, IR spectroscopy, and EXAFS.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 958–959, May, 1994.     

Luminescence Spectral Properties of Europium(III) and Terbium(III) Complexes with Cinnamic Acid

Europium and terbium mixed-ligand complexes with cinnamic acid of composition Ln(Cin)₃· nD · xH₂O, where Ln = Eu³⁺or Tb³⁺, Cin is a cinnamate ion (C₆H₅CH=CHCOO^–), D = 1,10-phenantroline, 2,2"-dipyridyl, benzotriazole (n= 2, x= 0), triphenylphosphine oxide (n= 1, x= 2), or H₂O (n= 0 or 1, x= 0), were synthesized. The compounds were characterized by elemental analysis, IR and luminescence spectroscopy. The Stark structure of the ⁵ D ₀–⁷ F _j(j= 0, 1, 2) electronic transitions in the low-temperature luminescence spectra of europium complexes was analyzed. IR study has revealed a bidentate coordination of the cinnamate ion in the compounds.     

Mechanochemical synthesis of mixed-ligand europium β-diketonates with nitrogen-containing neutral ligands

The solid-phase reaction between europium salts of β-diketones and nitrogen-containing neutral ligands in a planetary mill produces luminescent mixed-ligand compounds Eu(β-dic)₃ · D, where β-dic stands for dibenzoylmethane (DBM), benzoylacetone (BA), thenoyltrifluoroacetone (TTA), or benzoyltrifluoroacetone (BTFA); and D stands for 1,10-phenanethroline (Phen), 2,2-dipyridyl (Dipy), or diphenylguanidine (DPG). The mechanosynthesis and yield of lanthanide β-diketonates are studied as affected by the treatment parameters and the nature of the reagents. Powder X-ray diffraction demonstrates a staged course of the mechanochemical synthesis. Examination of formation-rate curves shows that grinding/stirring is the rate-controlling stage of the process. Thermogravimetric analysis (TGA) shows that the mechanosynthesis can proceed in the self-propagation mode. The relative luminescence intensity is determined as a function of treatment time. Particles of the mechanically activated mixture have sizes of 10–100 μm.     

Crystal structure of boron difluoride acetylnaphtholates

The crystal structure of luminescent isomeric boron difluoride acetylnaphtholates: 2-acetyl-1-naphthoboron difluoride (1) and 1-acetyl-2-naphthoboron difluoride (2) has been studied. Molecules of 1 make infinite stacks of coplanar molecules in crystals, and molecules of 2 are arranged in the crystalline cell in the form of isolated π-dimers. Unlike a planar molecule of 1, the methyl group in α-position of the diketonate ring drops out of the molecule plane in a molecule of 2, thus forcing the chelate ring to bend considerably along the line C(11)-B. The structure features of 1 cause a bathochromic shift of the luminescence band in comparison with 2.     

Transversals for Families of Translates of a Two-Dimensional Convex Compact Set

The following Theorem 1 gives an affirmative answer to Grünbaum's old question. Let F be a family of translates of a convex compact set K⊂R ² . If every two elements of F have a common point, then there exist three points A, B, C ∈ R ² such that every element of F contains some of these points. Received December 28, 1998, and in revised form October 20, 1999. Online publication May 15, 2000.     

Eigenstates of the quantum Penning-Ioffe nanotrap at resonance

We discuss the choice of physical parameters of a quantum Penning nanotrap under the action of a perturbing inhomogeneous Ioffe magnetic field and also the role of frequency resonance modes. We present a general scheme for constructing the asymptotic behavior of the eigenstates by the generalized geometric quantization method and obtain the reproducing measure in the integral representation of eigenfunctions.     

Kadets-Type Theorems for Partitions of a Convex Body

For convex partitions of a convex body B, we try to put a homothetic copy of B into each set of the partition so that the sum of the homothety coefficients is at least?1. In the plane this can be done for an arbitrary partition, while in higher dimensions we need certain restrictions on the partition.