卷 87, 编号 1 (2017)

The state of water in the nanocrystals of zirconium dioxide prepared via hydrothermal synthesis has been studied. Water molecules are localized at the nanoparticles surface as well as in the crystal structure of tetragonal modification of zirconia. The effect of water elimination on the structural transformations in the nanocrystals has been analyzed. Stabilization of tetragonal modification of zirconia at the lower temperature range is related to the presence of water in the nanocrystals.

Monoesters of malonic and succinic acids have been prepared in high yields by the BF₃·OEt₂-catalyzed addition of the acids to bicyclo[2.2.1]hept-2-ene. The synthesized monoesters were introduced in the reaction of esterification with saturated monoatomic alcohols С₂–С₇ in the presence of the KU-2-8 catalyst in the H-form, and the corresponding mixed diesters of dicarboxylic acids were obtained in high yields.

The benzylation of benzothiazole(oxazole, imidazole)-2-thiones with 3,5-di-tert-butyl-4-hydroxybenzyl acetate involves either the sulfur or nitrogen atom depending on the reaction conditions. The S- and N-benzylation products of benzazole-2-thiones are kinetically and thermodynamically controlled products, respectively. The use of 3,5-di-tert-butyl-4-hydroxy-benzyl acetate allows sterically hindered hydroxybenzyl derivatives of benzаzole-2-thiones to be generally synthesized under milder conditions than in known methods of their synthesis.

New substituted barbituric acid derivatives containing a 4,5,6,7-tetrahydroindole moiety have been synthesized by three-component condensation. Luminescence of crystals and solutions of the compounds synthesized have been studied; a maximum luminescence intensity and a minimum Stokes shift have been found in the 1-naphthyl derivative.

The structure of 2-hydroxy-5-isobutyl-1,3,2-dioxaborinane, one of the major autooxidation products of 5-isobutyl-2-isopropyl-1,3,2-dioxaborinane, has been studied by ¹H, ¹³C, and ¹¹B NMR spectroscopy together with X-ray analysis. Molecules of the title compounds adopt a sofa conformation with equatorial isobutyl substituent. The ring interconversion path, free conformational energy, and optimal conformation of the isobutyl group (corresponding to the X-ray diffraction data) were determined by DFT quantum chemical calculations at the PBE/3ξ level of theory.

2-(2-Hydroxyaryl)imidazolidines were synthesized by reaction of aromatic carbonyl compounds with N,N′-dialkylethylenediamines. The title compounds were also prepared using the corresponding Schiff bases instead of carbonyl compounds. Phosphorylation of 2-(2-hydroxyphenyl)imidazolidines with phosphoryl and phosphorothioyl chlorides and phosphorochloridites was accomplished. The reaction of O-phosphorylsalicylaldehyde with N,N′-dialkylethylenediamines also afforded 2-(2-hydroxyphenyl)imidazolidines.

N-{2-[5-(2-Hydroxyphenylmethyleneamino)-1-alkylbenzimidazol-2-yl]phenyl}-4-methyl-benzenesulfamides (H₂L) and their zinc complexes Zn₂L₂ were synthesized. The structure of the ligands and complexes was studied by IR, UV, ¹Н NMR, X-ray absorption spectroscopy, and X-ray diffraction analysis. The complexes show green photoluminescence (λ_fl = 492 nm) with quantum yields φ = 0.07–0.17.

The reaction of an aqueous suspension of basic cobalt carbonate CoCO₃·4Co(OH)₂·3H₂O with equimolar amount or two-fold excess of 1-hydroxyethylydenediphosphonic acid (H₄L) has yielded crystalline CoH₂L and amorphous Co(H₃L)₂ products, respectively. The interaction of poorly soluble CoH₂L complex with 2-aminoethanol has resulted in the formation of amorphous water-soluble CoH₂L·H₂NCH₂CH₂OH·6Н₂О complex; the latter loses 5 water molecules at heating and is converted into CoH₂L·H₂NCH₂CH₂OH·Н₂О. The study of agrochemical effects of Co(H₃L)₂ and CoH₂L·H₂NCH₂CH₂OH·6Н₂О has revealed their advantage over the conventional salt form (cobalt sulfate) reflected in the reduced phytotoxicity of the element. The prepared compound containing 2-aminoethanol (solubility promotor) has revealed better performance.

The interaction in the GeCl₄–nicotinoyl(isonicotinoyl, 2-, or 4-aminobenzoyl) hydrazone of 2-hydroxybenz(2-hydroxy-1-naphth)aldehyde (H₂L)–CoCl₂–methanol systems has resulted in the formation of [Ge(L·H)₂][CoCl₄]·nCH₃OH complexes with germanium chelates [Ge(L·H)₂]²⁺ protonated at the exo chelate nitrogen atom (N_Py or NH₂) as the cation. The type of electrolytic dissociation and character of thermolysis of the complexes have been revealed. Spectral, thermal, and magnetic properties of the complexes have been studied.

Complexes [Ph₃P(CH₂)₃PPh₃][PdBr₄] and [Ph₃P(CH₂)₃PPh₃][Pd₂Br₆]·DMF were synthesized by the reaction of dihydrogentetrabromopalladic acid with trimethylenebis(triphenylphosphonium) dibromide in water with subsequent recrystallization from N,N-dimethylformamide. The recrystallization of the first of them from dimethyl sulfoxide leads to the formation of the complex [Ph₃P(CH₂)₃PPh₃][PdBr₃(DMSO-S)]₂. Structure of the complexes was investigated by the X-ray diffraction (XRD) analysis.

Palladium(II) is efficiently extracted with (RS)-1-[2-(2,4-dichlorophenyl)pentyl]-1H-1,2,4-triazole from 0.2–5.0 M HNO₃ solutions and can be selectively separated from Ni(II), Cu(II), Pb(II), Fe(III), and Ag(I) in the acidity range specified, as well as from lanthanides(III) in 2–4 M HNO₃ solutions. The extraction of Pd(II) from 1 M HNO₃ solution proceeds via coordination mechanism; this is an endothermic process in the 10–30°C temperature range. Palladium(II) is completely stripped with a nitric acid solution of thiourea or with 3–4 M NH₄OH solution.

Electrochemical oxidation of N-(3-methoxysalicylidene)-o-anisidine and the corresponding Zn(II) complex under potentiodynamic and potentiostatic conditions has resulted in the formation of conductive polymer films on the surface of platinum electrode. Optimal conditions (potential and duration of electrode polarization in a solution of the monomer) of potentiostatic synthesis of polymeric azomethine have been elaborated. Diffusion coefficients of charges and activation energies of charge transfer in the studied polymers are reported.

Synthesis of tri- and five-membered carboxylates are discussed. Microwave irradiation has been shown to stimulate the condensation of СН-acids with allyl chlorides. The selectivity of formation of target products was depending on the CH-acid structure. Structures of the isolated compounds have been confirmed by ¹Н and ¹³С NMR spectroscopy and chromato–mass spectrometry data.

The interaction of 4-oxo-1,3-benzoxazinium perchlorate with 2-pyridylhydrazine has given 5-(2-hydroxyphenyl)-3-ethyl-1-(pyridin-2-yl)-1Н-1,2,4-triazole (L). Boiling of the latter in methanol with 0.5 equiv of beryllium sulfate tetrahydrate has afforded the L₂Be metal complex. In contrast to the starting triazole, its beryllium complex exhibits strong violet luminescence (λ_max^fl = 431–434 nm, φ = 0.56–0.64).