F. A. Kolokolov

Synthesis and luminescence of complexes of europium(III) and terbium(III) with pyridinedicarboxylic acids

Complex compounds of lanthanides with carboxylcontaining ligands are among the most promising classes of materials for the creation of electroluminescent devices [1–3]. The luminescence intensity of lanthanide coordination compounds depends on the degree of absorption of electrical or electromagnetic energy by the organic ligand and its transmission to the lanthanide ion. Thus, the molecular design of promising luminescent lanthanide compounds is reduced to the selection of ligands that can effectively absorb and transfer the energy to the lanthanide ion. We have previously produced the efficiently luminescent compounds of Tb and Eu with aminocarbonylphenoxyacetic [4, 5], dimethoxybenzoic [6, 7], and 1,10phenanthroline-2,9-dicarboxylic acids [8]. It was interesting to synthesize and study the fluorescent properties of complexes of terbium(III) and europium(III) with pyridinedicarboxylic acids. As is known [9], coordination compounds of europium(III) and terbium(III) with pyridine-2,6-dicarboxylic (dipicolinic acid) have a high efficiency of luminescence in the visible region. However, there are no data on the luminescent properties of Eu and Tb complexes with the other pyridinedicarboxylic acid. Therefore, the aim of this work was synthesis and study of the luminescence of coordination compounds of europium(III) and terbium(III) with 2,4-pyridinedicarboxylic (lutidinic, Hlutid), 3,4-dicarboxylic (cinchomeronic, Hcinch), and pyridine-3,5-dicarboxylic (dinicotinic, Hdinic) acids.

Lanthanide complexes with 2,4-dimethoxybenzoic acid

In this connection, we carried out synthesis of the lanthanides complex compounds with 2,4-dimethoxybenzoic acid (HL) [LnL3(H2O)2]·6H2O, where Ln = Sm, Eu, Gd, Tb, Dy. The complex compounds were synthesized by the reaction of water–alcohol solution of the corresponding lanthanide chloride and the ligand ammonium salt in a 1:5 molar ratio at pH ≈ 6.5. The resulting precipitate was filtered off, washed with alcohol, water and dried in air.

Electrochemical synthesis of anhydrous luminescent Tb 3+ complexes with aromatic and heterocyclic carboxylic acids

The electrochemical synthesis of anhydrous terbium(III) complex compounds TbL3 and Tb2L3 with several aromatic and heterocyclic carboxylic acids has been performed. Thermal stability of the synthesized complexes has been studied by means of thermogravimetry, and terbium(III) 4-tert-butylbenzoate has been found the most thermally stable (up to 400°C). Luminescent properties of the obtained compounds have been studied, and the terbium(III) complex with 2,3-pyridinedicarboxylic acid has exhibited the most efficient luminescence.

Synthesis and Luminescent Properties of Terbium(III) and Europium(III) Fluoride Nanoparticles Modified with Aromatic Carboxylic Acids

Europium(III) and terbium(III) fluoride nanoparticles modified with citric, anthranilic, benzoic, salicylic, and acetylsalicylic acids have been obtained by means of sorption from solution and modification in statu nascendi. The shape and size of the particles have been determined by scanning electron microscopy. The luminescence of the samples was studied and it has been established that terbium fluoride nanoparticles modified with acetylsalicylic acid exhibits the highest luminescence intensity.

Features of the complexation of octadecane-2,4-dione and lanthanide ions in Langmuir monolayers

Monolayers of octadecane-2,4-dione on the surfaces of EuCl3 and TbCl3 solutions in the concentration range of 1 × 10–4 to 5 × 10–3 M at pH 5.8 are studied. It is found that the limiting area of octadecane-2,4-dione molecule in a monolayer dependence on Eu3+ and Tb3+ concentration is of extreme nature. The formation of complex compounds in the ligand monolayer is postulated, and structures are proposed for these compounds at different concentrations of metal ions.

Synthesis of 3-tetradecylpentane-2,4-dione and investigation of its compression isotherms by the Lengmuir-Blodgett method

By alkylation of acetylacetone in anhydrous methanol 3-tetradecylpentane-2,4-dione was prepared. Its individuality and structure were confirmed by IR and NMR spectroscopy and mass-spectrometry. Compression isotherms of the Lengmuir monolayers on water subphase surface depending on the tautomeric form of 3-tetradecylpentane-2,4-dione were studied.

Synthesis of copper(II) coordination compounds with benzoxazine derivatives

Copper(II) complexes with 1,2-dihydro-4H-3,1-benzoxazine (HL) derivatives, CuLOH, were prepared by anodic electrosynthesis. The use of an amalgamated copper anode resulted in an increase in the electrosynthesis rate. It follows from the IR spectra of the products that the benzoxazine ring in the ligand molecule is opened upon complexation, while a six-membered chelate ring involving the oxygen atom of the deprotonated phenol group and the imine nitrogen atom is formed.

The copper(II) acetate complex with 2-(2-Hydroxyphenyl)-4,4-diphenyl-1,2-dihydro-4H-3,1-benzoxazine

The Cu(II) acetate complex with 2-(2-hydroxyphenyl)-4,4-diphenyl-1,2-dihydro-4H-3,1-benzoxazine (L) was synthesized for the first time and structurally studied by X-ray diffraction. The complex crystallizes as two crystallographically independent centrosymmetric binuclear molecules [Cu2(μ-L)2Ac2] of similar structure, where L occurs as azomethin tautomeric form. The ligand performs tridentate chelate-bridging function. Each Cu atom exhibits extended tetragonal-pyramidal coordination by two O atoms and the N atom of one ligand L in the equatorial plane and by the O atom of the second ligand L in the axial position. The fourth equatorial position in the metal coordination polyhedron is occupied by the O atom of monodentate terminal acetate group.

Synthesis and study of copper(II), nickel(II), and cobalt(II) complex compounds with dihydrobenzoxazine derivatives

Complex compounds ML2 of copper(II), nickel(II), and cobalt(II) with 2-(2-hydroxy-5-nitrophenyl)-4,4-diphenyl-1,4-dihydro-2H-3,1-benzoxazine and 2-(2-hydroxyphenyl)-4,4-diphenyl-1,4-dihydro-2H-3,1-benzoxazine (HL) were prepared by electrochemical and chemical syntheses. The complex formation involves the azomethine form of the ligand and gives a six-membered chelate cycle comprising deprotonated phenol and azomethine groups. The coordination entity has a planar structure with trans arrangement of the nitrogen and oxygen atoms.