Vol 89, No 12 (2019)

Cyclic acetals of furan aldehydes (furfural, 5-hydroxymethylfuran-2-carbaldehyde and furan-2,5-dicarbaldehyde) and alcohols (ethylene glycol and 2-sulfanylethanol) were synthesized. The effect of the ratio of the starting reagents on the yield of acetals obtained was studied.

Alkylation of 4,8-dimethyl- and 4,6,8-trimethylquinolin-2(1H)-one with allyl bromide in the presence of a base proceeds at the oxygen and nitrogen atoms with the predominant formation of the O-isomer. The reaction of 2-allyloxyquinolines with halogens leads to the formation of oxazolo[3,2-a]quinolinium salts. Structure of 1-bromomethyl-5,7,9-trimethyl-1,2-dihydro[1,3]oxazolo[3,2-a]quinolinium iododibromide was established by single crystal X-ray diffraction method.

A method was developed for the synthesis of new fused derivatives of pyrano[4,3-b]thieno(furo)-pyridine, namely 8,8-dimethyl-11-(2-furyl)-7,10-dihydro-8H-pyrano[3″,4″:5′,6′]pyrido[3′,2′:4,5]thieno(furo)[3,2-d]- pyrimidine-4(3H)-ones, from 2,2-dimethyltetrahydropyran-4-one. Optimal conditions for carrying out the cyclization reaction of ethyl {7,7-dimethyl-4-(2-furyl-3-cyano-7,8-dihydro-5H-pyrano[4,3-b]pyridin-2-yl]oxy}acetate into the corresponding amino ester were determined.

The reactions of quinazoline with 1,3,5-trimethoxybenzene, 3- and 4-methylbenzene-1,2-diamines, and 1-(4-methoxybenzylidene)-2-phenylhydrazine on heating in the presence of trifluoroacetic acid afforded the corresponding stable C–C σ-adducts.

S-Methyl diethylphosphinothioate reacted with benzylidene chlorides to give the corresponding aryl(chloro)methyl methyl sulfide and diethylphosphinoyl chloride. The product structure suggests initial attack of the methylsulfanyl group on the CH carbon atom of dichloromethylarene. Arenecarbothialdehyde dithioacetals and trimers and O,O-dialkyl[aryl(methylsulfanyl)methyl]phosphonates were synthesized.

A new tetrazole tripodal ligand, tris[2-(tetrazol-5-ylmethoxy)phenyl]phosphine oxide, has been obtained. Its structure in crystal and solutions has been elucidated by X-ray diffraction analysis as well as IR, Raman, and multinuclear (¹H, ¹³C, ³¹P) NMR spectroscopy. Coordination properties of the polydentate ligand have been studied as exemplified by the complexation with lanthanum(III).

New complex compounds LnL₃·nH₂O (n = 5–10) have been synthesized on the basis of Eu³⁺, Gd³⁺, and Tb³⁺ salts and quinoline-4-carboxylic acid derivatives obtained via the Pfitzinger reaction. Composition and structure of the ligands and the resulting complex compounds have been confirmed by NMR and IR spectroscopy, thermogravimetry, and complexometric titration. Europium complex with 1,2,3,4-tetrahydroacridine-9-carboxylic acid has exhibited efficient luminescence.

Membrane transport of mono- and polyfunctional carboxylic acids mediated by phosphorylated diamines has been studied. The structure of complexes transferred through the membrane has been discussed; in some cases, a relation has been found between the efficiency of membrane transport of organic acid substrates and the structure of membrane carriers and their complexes with the acids. A correlation between the transmembrane flow and shift of some characteristic IR absorption bands (as well as change of their intensity) of the substrate–carrier complexes in comparison to the corresponding substrates and carriers has been estimated.

A new approach to the preparation of a nanosized sorbent based on magnesium phosphate has been developed. The patterns of copper(II) ions sorption with nanosized magnesium phosphate from aqueous solutions have been investigated. The sorption parameters have been determined, and the kinetics and mechanism of the processes have been elucidated. The high sorption ability of the nanoscale sorbent has been shown in comparison with existing sorbents based on magnesium phosphate.

The processes occurring during the mechanical activation of a-Fe₂O₃ (hematite) in the presence of oleic acid in a centrifugal-planetary mill have been investigated. Mechanical activation for 10 h afforded hematite powder with particles size of 10–40 nm, as shown by means of X-ray diffraction analysis, FTIR spectroscopy, high-resolution transmission electron microscopy, and specific surface area measurements. Longer milling has led to mechanochemical transformation of hematite into Fe₃O₄ (magnetite).

The effect of electronic properties of substituents in the reactants on the [4+2]-cycloaddition of 3-vinyl-chromen-4-ones (dienes) and N-vinylpyrrolidines (dienophiles) has been studied. The conditions determining the formation of 4,4a-dihydroxanthones or benzophenones as the major products have been found. The aromatization of 4,4a-dihydroxanthones via pyran ring opening has been interpreted by quantum chemical calculations. A wide series of new 4,4a-dihydroxanthone and benzophenone derivatives have been isolated.

Fluorozirconate-phosphate glasses of the ZrF₄–BaF₂–NaPO₃(LiPO₃) and ZrF₄–BaF₂–LaF₃–AlF₃–LiPO₃ systems doped with EuF₃, ErF₃, and NdF₃ were studied by the differential-thermal (DTA) and X-ray diffraction (XRD) analysis, luminescence spectroscopy, scanning and transmission electron microscopy (SEM and TEM) methods. Addition of the phosphate component up to 20 mol % decreases the glass transition temperature and increases the glass stability to crystallization. Heat treatment in the range >T_g–T_c1 of glass transition and first maxima of crystallization temperatures causes crystallization of nanosized β-BaZrF₆ particles. At LiPO₃ (NaPO₃) concentrations of more than 80 mol %, glasses containing a crystalline phase are formed during the synthesis process.

A series of novel 1,2,4-oxadiazole-isoxazole linked quinazoline compounds is designed, synthesized and screened for anticancer activity on four human cancer cell lines including MCF-7 (breast), A549 (lung), DU-145 (prostate), and MDA MB-231 (breast) by using MTT assay with etoposide used as a positive reference. All compounds demonstrate good to moderate anticancer activity and two compounds are found to be the most potent.

The main-chain phosphorescent polymers, PFCzIr(PhStz) and PFOIr(PhStz) with iridium complex (4-BrPhBt)₂Ir(Pytz), are synthesized by the Suzuki polycondensation, in which the fluorene-carbazole and fluorene segments are used as a polymer backbone. The studied photoluminescent and electroluminescent properties demonstrate good overlap of the emission spectra of poly(fluorene-carbazole) (PFCz) or polyfluorene (PFO) host and the absorption spectra of the iridium complex guest that meets requirements for the efficient Forster transfer from the host polymer to the iridium complex in polymers. With the increase of the content of iridium complex, the host emission intensity decreases, while the guest emission intensity gradually increases. As compared with PFOIr(PhStz), host-guest system in PFCzIr(PhStz) is more efficient in Forster energy transfer, and the photoluminescence and electroluminescence properties are more sound. Among all polymers, PFCzIr(PhStz) 5.0 demonstrates the best performance in electroluminescence, its fluorescence quantum is 22.74%. The devices fabricated from PFCzIr(PhStz)5.0 exhibit yellow-red emission with a maximum brightness of 1568 cd/m² at 14 V, luminous efficiency and power efficiency reach 6.24 cd/A and 2.45 lm/w.

Zn(II) complexes of N-(quinolin-8-yl)picolinamide (HL¹) (1) and N²,N⁶-di(quinolin-8-yl)pyridine-2,6-dicarboxamide (H₂L²) (2) have been synthesized by deprotonation of the ligands and characterized by IR, NMR, and Single crystal X-ray crystallography. The mononuclear [Zn(L¹)₂] (3) and homodinuclear [Zn₂(L²)₂] (4) complexes are characterized by distorted octahedral geometries stabilized by hydrogen bonding and weak π···π interaction. The complexes demonstrate intense fluorescence bands in comparison with their corresponding ligands with well-distinguished intensity. The complexes act as efficient catalysts in various transesterification reactions. Among those, the best results have been achieved with complex 3 in conversion of 4-nitrophenylacetate into methyl acetate within 3 h.

This article is focused on preparation of Ni(II), Pd(II) and Ru(III) oxides in the nanoscale form from the complexes of N,N,N,N-tetradentate Schiff base with Ni(II), Pd(II) and Ru(III). The complexes have been synthesized and characterized by elemental analyses, magnetic susceptibility, molar conductivity, ¹H and ¹³C NMR, FT-IR, UV-Vis, mass, and TG-DTG analysis. The accumulated data indicate that the central metal ion in the complexes is coordinated with four nitrogen atoms of the imino and amino groups. The complexes are characterized by a 1 : 1 metal : ligand ratio and octahedral geometry except for Pd(II) complex which has a tetradentate structure. The complexes have been used as precursors for NiO, PdO and RuO₂ preparation of NPs by thermal decomposition at 600°C in the static air. Formation of the NPs is discussed in terms of FTIR, XRD, SEM, and TEM analyses data. The rate of catalytic decoloration activity of Malachite green dye under the action of metal oxides is considered. The dye has been successfully decolorized in presence of the NPs at room temperature.

A series of C7-substituted-2-morpholino-N-(pyridin-2-ylmethyl)quinazolin-4-amine derivatives 3a–3t were synthesized by using Nickel catalyzed Kumada cross coupling reaction. The structure of the key intermediate 2 was assigned using 2D COSY and 2D NOESY correlation spectrum. All the target compounds were characterized and tested for their antibacterial activity against Gram-positive organisms such as Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, and Gram-negative organisms such as Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia. The results indicated that compounds 3g–3m exhibited potent antibacterial activity with MIC values ranging from 1.17 to 4.68 μg/mL. These results are expected to be of help in understanding the structure activity relationship and further enable us to design novel antibacterial agents. Molecular docking of Escherichia coli Biotin Carboxylase (EcBC) enzyme was also performed in order to study the interactions of the synthesized compounds.

Two efficient procedures have been developed for the synthesis of pyroglutamic acid analogues 28, 29, and 34. According to the first method the Ugi (4C3C) reaction is followed by a post-transformation reaction, and the second method involves the Michael addition reaction. The present methodologies demonstrate the applicability of 1-(2,2-dimethoxyethyl)-2-isocyanobenzene (15) as a cleavable isocyanide in the Ugi/ post-transformation reaction and a strong nucleophile in the Michael addition reaction. The framework of pyroglutamic acid analogues has been constructed by the selective cleavage of the C-terminal amide bond and nucleophilic addition to the activated α,β-unsaturated carbonyl group.

Two curcumin derivatives, 1,7-bis(4-bromoethyloxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione (1) and 1,7-bis(4-bromobutyloxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione (2), have been conveniently synthesized and their structures characterized by ¹H NMR and mass spectra, and single crystal X-ray diffraction measurements. Single-photon and two-photon fluorescence properties have been studied. The calculated two-photon absorption cross-sections for both compounds by quantum chemical method are as high as 358 and 326 GM, respectively. Two-photon fluorescent imaging of MCF-7 cells labeled with the compound 1 indicates its potential application as a biological fluorescent probe.

A mild coupling reaction catalyzed by Ni(acac)₂-L4 has been studied. The catalyst acts efficiently in the reaction of biaryl coupling between various electrophiles and common or functionalized aryl Grignard reagents with high functional group tolerance. The study demonstrates that LiCl acts as an essential component in efficient cross-coupling by accelerating reduction of Ni(II) to Ni(0). The new catalytic system for selective couplings of aryl tosylates with aryl chlorides has been developed.

The regio- and stereoselective synthesis of 3-ethoxy-2H,3H-[1,3]thiazolo[3,2-a]pyridin-4-ium halides via the reaction of 2-pyridinesulfenyl halides with vinyl ethyl ether has been elaborated.

The review presents the main results obtained by the Belorussian scientific school of Acad. G.P. Gurinovich and his followers in the in the research on the spectral kinetic properties and photonics of pigment-pigment interactions of chlorophyll and its close analogs in vitro (from highly concentrated solutions to structurally organized heterogeneous nanoassemblies of various morphology), as well as on the interactions of multiporphyrin nanoassemblies with molecular oxygen. The adequacy of various theoretical models that describe the primary processes of photosynthesis (electronic excitation energy transfer and photoinduced charge transport) at short interchromophore distances, considering the properties of the medium and the conformational dynamics of interacting subunits, is substantiated. Application-oriented aspects concerning the use of multicomponent nanostructures on the basis of photostable tetrapyrrole compounds with controllable electron-transport properties and conformational mobility for the development of element base in molecular electronics, photonics, medicine, and nanobiotechnology are considered in brief.

Issues of preservation of the self-color of gray linen fabrics were discussed. Textiles preparation variants and their influence on the color characteristics of flax were considered. For preserving the chromophoric structure of lignin, enzymatic and plasma treatment methods were proposed.

Data on sorption of rare, noble, radioactive, and nonferrous metals from aqueous solutions by impregnates and TVEXs were analyzed. These are materials combining the properties of sorbents and extractants and differing in the production method. Their distinctive feature is that the extractant is not chemically bonded to the solid support, which is responsible for high kinetic characteristics of sorption processes involving these materials, favorably comparing with conventional sorbents. As a mobile phase to be deposited on the carrier (mainly polymeric) in the case of impregnates or to be introduced during synthesis of TVEXs served organophosphorus extractants, amines, quaternary ammonium bases, etc. Information regarding the effect of various parameters (solution acidity, metal concentration, phase ratio, temperature, and concentration of impurity elements) on separating capability and metal sorption capacity and kinetics was provided for this type of materials. Methods used for stabilizing the properties of impregnates with the view to minimize the extractant loss during application were considered.