Vol 87, No 11 (2017)

The formation of bismuth orthoferrite under hydrothermal conditions at temperature 160, 180, or 200°С and pressure 100 MPa in aqueous solution of potassium hydroxide has been studied. The determined composition and structure of polycrystalline phase with sillenite structure have evidenced its formation at the interface of the crystallites of amorphous iron oxide. It has been shown that the formation of polycrystalline round-shaped BiFeO₃ particles with size about 20 μm occurs via aggregation of perovskite-type phase crystallites (38–70 nm). Pycnometric density of BiFeO₃ and the amorphous phase has been determined, and Mossbauer spectra reflecting the state of iron in the phases coexisting during the formation of BiFeO₃ have been analyzed.

On the basis of the data of ESR and magnetic susceptibility of Bi₂BaNb_2–2xMn_2xO_9–δ solid solutions with perovskite-like structure ferro- and aniferromagnetic bonded dimers, trimers, and tetramers of Mn(II), Mn(III), and Mn(IV) atoms in various valence states were found. The distribution of aggregates and exchange parameters in the clusters were calculated as a function of fraction x of manganese atoms in the solid solutions. In the ESR spectra of diluted solid solutions there are absorption bands with g-factors ~4.3 and 2.1 assigned to Mn(II) and Mn(IV) atoms.

The reactions of hydrogen transfer from 2-propanol on acetophenone in the presence of the system [Rh(cod)Cl]₂–L] (L is bisaldimine ligands based on (R,R)-1,2-cyclohexanediimine and pyridine-, quinoline-, and thiophenecarboxaldehyde) were studied. Rhodium(I) complexes with optically active ligand showed a high catalytic activity (up to 345 h^–1) and moderate enantioselectivity [up to 55% ee of (R)-1-phenyethanol]. The structure of rhodium complex with N,N'-(1R,2R)-cyclohexane-1,2-diyl-bis[1-(pyridine-2-yl)methanimine] was determined on the basis of the data of ¹H and ¹³C NMR spectroscopy and quantum chemical calculations.

Cross effects of the reagent structure and the temperature on the rate and activation parameters of the reactions of symmetrically X-substituted trans-2,3-diaryloxiranes with Y-substituted arene-sulfonic acids have been investigated in the temperature range 265–298 K. The isokinetic temperature of 265 K was reached, at which the rate and the free energy of the ring-opening reaction of trans-2,3-bis(3-bromo-5-nitrophenyl)-oxirane practically do not depend on substituent Y. The transition through the isoparametric points on substituent Y was realized with the inversion of the temperature effect on the free energy of activation for the reactions of oxiranes with X = 4-NO₂ and 3-Br-5-NO₂.

By reaction of halomethyl derivatives of phosphonocarboxylates of the furan series with sodium azide corresponding azidomethyl compounds were synthesized. Treating them with triphenylphosphine in ethanol results in primary amines. Seven of the twelve possible position isomers of the aminomethyl phosphonocarboxylates were obtained. Method was found of selective dealkylating phosphonates leaving intact the ester group present in the molecule.

Potassium and tin(II) derivatives of the paramagnetic forms of the redox-active 2,6-bis(2,6-diisopropylphenyliminomethyl)pyridine were synthesized and studied by means of EPR spectroscopy. It was shown that the reaction with metallic potassium involves the three-electron step reduction of the organic ligand to form a radical anion, dianion, and trianion radical, respectively. The reactions of the tin(II) diiminopyridine derivatives with metallic magnesium give complexes comprising the radical anion form of the ligand and a low-valence metal center. The geometries of the paramagnetic products and their spin density distributions were explored in terms of the density functional theory.

The reaction of trimethylantimony with methacrylic acid in the presence of tert-butyl hydroperoxide gave trimethylantimony dimethacrylate Me₃Sb(O₂CCMe=CH₂)₂ whose structure was confirmed by elemental analysis and IR, ¹H and ¹³C NMR, and mass spectra. According to the X-ray diffraction data, the title compound is a trigonal–bipyramidal antimony complex with three methyl group in the pyramid base and two methacrylate ligands in the apices.

cis-[PdCl₂(CNR)(PPh₃)] [R = Cy, t-Bu, C(Me)₂CH₂C(Me)₃] have been synthesized via the interaction of [(PPh₃)ClPd(μ-Cl)₂PdCl(PPh₃)] with isocyanide in CH₂Cl₂ at room temperature with 90–98% yield and characterized by means of mass spectrometry as well as ¹H, ¹³C{¹H, ³¹P}, and ³¹P{¹H} NMR spectroscopy. The complexes structure in the solid phase has been elucidated by means of X-ray diffraction analysis. Dynamic processes in the solutions of the complexes in CDCl₃ and CD₂Cl₂ at temperature of–95 to 60°С have been studied by means of ¹H and ³¹P NMR spectroscopy. It has been found that the studied compounds existed exclusively in the cis-[PdCl₂(CNR)(PPh₃)] form in the solutions. In the case of cis-[PdCl₂(CNCy)(PPh₃)] in CH₂Cl₂, the conformational transitions of the equilibrium forms (the transition of the substituent in the cyclohexyl cycle between the equatorial and axial positions) are slowed down, the equatorial conformer prevailing in the solution (2: 1 at–95°С). Quantum-chemical simulation (DFT) has revealed that the standard Gibbs energy of the conformational transition from the axial form of cis-[PdCl₂(CNCy)(PPh₃)] into the equatorial one in the CH₂Cl₂ solution at 178 K equals–2.5 kJ/mol, being in agreement with the experimental data.

Novel organometallic surfactants were synthesized from monoquaternized 1,4-diazabicyclo[2.2.2]-octanes of varied hydrophobicity [Alk = C_nH_2n+1, n = 14, 18] and lanthanum nitrates. The spectral, micelleforming, and adsorption properties of the synthesized compounds were studied by IR, ¹Н NMR and electronic spectroscopy, tensiometry, conductometry, and potentiometry. The critical micelle concentrations, counterionic micellar binding constants, and adsorption parameters at the water–air interface were determined and compared with the respective characteristics of the ligands and conventional amphiphiles.

Istaroxime 1, a novel cardiotonic agent with high efficiency and low toxicity was synthesized from dehydroepiandrosterone 2 using a novel approach that included epoxidation, ring-opening, substitution, and oximation. The new protocol without gas protection was milder than the reported approaches. The overall yield of the method was 24.1%.

A new series of metal(II) complexes 1–5 of the type [M(L)(AcO)₂H₂O], where L is a bidentate ligand, 2-(3-morpholinopropylimino)methylphenol and M is Mn(II) (1), Co(II) (2), Ni(II) (3), Cu(II) (4), and Zn(II) (5), have been isolated and characterized by physico-chemical and spectral methods. Spectroscopic data supported the square pyramidal geometry around the central metal ion in the complexes 1–5. Absorption spectra and viscometric data indicated that the complexes 1–5 interacted with calf thymus (CT) DNA via intercalative strategy. Cleavage activities of complexes 1–5 with CT DNA were analyzed by gelelectrophoretic method. The in vitro antioxidant activity of complexes 1–5 was tested using the DPPH assay. The complexes 1–5 have been tested for antimicrobial activity against some pathogenic bacterial and fungal species by the agar well diffusion method.

A series of diacylhydrazine derivatives containing 1,4-benzodioxan 1-17 has been designed, synthesized and evaluated for antitumor activity. Most of the synthesized compounds demonstrated potent antitumor activity and low toxicity. Compound 10 demonstrated the most potent biological activity against MCF-7 cancer cell line, which was comparable with the positive control 5-fluorouracil. Docking simulation by positioning compound 10 into the MetAP2 structure active site was performed to explore the possible binding model.

Six new ferrocenyl guanidines were synthesized and characterized by elemental analysis, FT-IR and ¹H and ¹³C NMR. Compounds 1–6 were screened for antioxidant, protein kinase inhibition, lethality of brine shrimp, and cytotoxicity against the human leukemia THP-1 cell line. The compounds demonstrated moderate to significant activities. Antioxidant activity of the synthesized compounds was evaluated by DPPH % inhibition with IC₅₀ values. All compounds 1–6 showed notable antioxidant activity with DPPH having IC₅₀ values between 23.2–15.1 and noteworthy brine shrimp lethality. Compound 6 demonstrated the highest cytotoxicity against brine shrimps with LC50 of 9.09 μg/mL. Protein kinase inhibition activity showed significant hyphea formation inhibition at 100 μg/disc with 10 to 13 mm clear zone of inhibition for the compounds 2–6. The compounds were screened for in vitro cytotoxicity using human leukemia cell line (THP-1 ATCC#TIB-202). Among all compounds, the most significant activity was demonstrated by compounds 6 and 5 with IC₅₀ of 3.88 and 5.59 μg/mL which was comparable with the standard 5-flourouracil and vincristine drugs.

New series of pyrenyl–pyrazole based chalcones have been synthesized and characterized via the condensation of 1-(3-chlorophenyl)-3-(pyren-1-yl)-1H-pyrazole-4-carbaldehyde with different substituted acetophenones in alkaline media. Structures of the newly synthesized compounds were elucidated from spectroscopic and elemental analysis data.

A series of novel hybrid aza heterocycles containing pyrazolopyrimidinone and dihydropyrimidinone scaffolds was developed using Cu(II) catalyzed Biginelli condensation as an efficient, new green synthetic method under mild and solvent free conditions. Pyrazolopyrimidinone based aldehydes, alkyl acetoacetates and urea/thiourea were used as the components in the reaction to afford hybrid aza heterocycles in high to excellent yields. The products were screened for in vitro antibacterial activity and all of those demonstrated high to excellent activity.

It was found that the contact of the layered oxide Rb₂Nd₂Ti₃O₁₀ with an aqueous solution gives rise to a protonation process, which leads to lowering the oxide photocatalytic activity in reactions of hydrogen evolution from a water-alcohol solution.

One-pot indirect electrochemical oxidation of alcohols in the methylene chloride–aqueous solution of sodium hydrocarbonate two-phase system in the presence of potassium iodide, 4-acetylamino-2,2,6,6-tetramethylpiperidin-1-oxyl, and 2,6-lutidine results in the formation of the corresponding acid anhydrides with yield up to 80%. The reaction occurs at room temperature and is complete after passing 6 F/mol of electricity.

A multicomponent Biginelli reaction in a solvent-free conditions catalyzed by 1-methyl-2-oxopyrrolidinium perchlorate ionic liquid was studied. The сondensation of aromatic aldehydes, urea (thiourea), and acetoacetic ester yielded substituted 5-ethoxycarbonyl-3,4-dihydropyrimidin-2(1H)-ones(thiones) in 75–97% yield.

It was proved by the IR spectroscopy that the first coordination sphere of nickel cations in the NiCl₂·2DMSO·9H₂O, NiCl₂·5DMSO·4H₂O, and NiCl₂·4DMSO·2H₂O compounds contains dimethyl sulfoxide and water ligands. According to X-ray structural analysis, in crystals of the NiCl₂·4DMSO·2H₂O compound, noncovalent contacts between sulfur atoms of neighboring dimethyl sulfoxide molecules are realized in the inner sphere of the complex.

Nafion- and Aquivion-based composite solid polyelectrolytes containing deagglomerated detonation nanodiamonds were studied by the impedance spectroscopy method. It was found that introduction of these dopants leads to a substantial increase in proton conductivity of hybrid membranes with low relative humidity.