Vol 88, No 6 (2018)

Nanocomposites based on nanoparticles of iron oxides formed inside porous matrices were studied. Mesostructured silica material SBA-15 impregnated with an aqueous solution of iron(III) oxalate was heattreated in oxidizing (air) and reducing (Ar + 5% H₂) media. The resulting samples exhibited small oxide particle sizes (ca. 5 nm) and sufficiently uniform distribution of iron whose content was ~16 wt %.

Dissociation constants of 5-methoxy-6-methyluracil, 5-methoxy-1,6-dimethyluracil and 5-methoxy-3,6-dimethyluracil in water are determined. Basing on the obtained рK_а1 values, the content of anions in aqueous alkaline solution of 5-methoxy-6-methyluracil was calculated. The results were confirmed by the use of model compounds: 5-methoxy-1,6-dimethyluracil and 5-methoxy-3,6-dimethyluracil using the NMR spectroscopy.

The system thiourea dioxide–hydrogen peroxide is found to effectively hydroxylate coumarin in aqueous solutions. The hydroxyl radical reacting with coumarin is shown to result from decomposition of the complex thiourea dioxide–H₂O₂. The obtained data are compared to the results of investigation of the reactions occurring in the system thiourea dioxide–H₂O₂ with terephthalic acid.

The reaction of methyl aroylpyruvates and 2-(4-aminobenzenesulfamido)-4,6-dimethylpyrimidine in glacial acetic acid in the presence of anhydrous sodium acetate afforded (2Z)-4-aryl-2-hydroxy-N-{4-[(4,6-dimethylpyrimidin-2-yl)sulfamoyl]phenyl}-4-oxobut-2-enamides. Reaction of the above reagents in a mixture of acetic acid and ethanol (1: 1) in the absence of anhydrous sodium acetate gave methyl (2Z)-4-aryl-2-{4-[(4,6-dimethylpyrimidin-2-yl)sulfamoyl]phenylamino}-4-oxobut-2-enoates. Analgesic and anti-inflammatory activities of the synthesized compounds was studied.

α-(1,2,3-Triazole)-substituted acetals were obtained using the click procedure. Under acid hydrolysis conditions these acetals were converted into earlier unknown stable gem-diols containing a triazole ring.

Conditions for an efficient and a readily reproducible synthesis of a series of 2N-Alkyl-substituted 5-amino-3-imino-1,2,4-thiadiazolines by the direct alkylation of 3,5-diamino-1,2,4-thiadiazole with alkyl bromides in fairly high yields (up to 76%).

The interaction of ethylenediamine with pheophorbide a, carboxylic group of the latter being activated with di-tert-butyl dicarbonate, has been studied. Acylation of two amino groups of ethylenediamine with activated pheophorbide a and the formation of phorbine-phorbine dimer with the macrocycles bound in the dimer via amide bonding with ethylenediamine bridge have been demonstrated. It has also be found that the phorbine-phorbine dimer is formed even in large excess of ethylenediamine with respect to pheophorbide a.

The reaction of μ-carbidodimeric iron(IV) tetra-4-tert-butylphthalocyaninate with nitrogenous bases (imidazole and its derivatives, pyridine, diethylamine), which involves formation of donor‒acceptor complexes with a preserved dimeric structure, was studied by spectral methods. The composition of such molecular complexes and their comparative stability were determined. The coordination power of μ- carbidodimeric iron(IV) tetra-4-tert-butylphthalocyaninate was found to depend on the nature of the nitrogenous base and macrocycle. Quantum-chemical modeling of the coordination reaction was performed. The energetic and geometric characteristics of the donor‒acceptor complexes were obtained. The composition of the reaction products was shown to be affected of the degree of deformation of the macrocycle.

The interaction of Co(II)- and Co(III)-5,10,15,20-tetraphenylporphyrins with tert-butylhydroxyperoxide and di-tert-butylhydroxyperoxide in benzene at 298 K were studied by spectrophotometry and ¹H NMR spectroscopy. Kinetic parameters of the destruction reactions of porphyrin macrocycle depending on the nature of peroxide the valence of cobalt cation, and the presence and nature of axial ligands were calculated. Products of consecutive decomposition of tetrapyrrole macrocycle to monopyrroles were determined by mass spectrometry.

Photostability of B(III), Zn(II), Cd(II) complexes with monoiodo- and dibromosubstituted dipyrromethenes [BF₂L] and [ML₂] in benzene and cyclohexane solutions is studied. It is found that the mechanism of destruction of the dyes under UV radiation is based on participation of singlet oxygen generated by the excited triplet state of the dye. Singlet oxygen enters the oxidation reactions of the pigment molecules leading to accumulation of colorless products based on di-, monopyrrol, and smaller fragments. Initial stages of the process include the reactions of dehalogenation of the dye molecules and are accompanied by enhancement of the fluorescence of the formed alkyl-substituted dipyrromethenates. The photostability of boron complexes [BF₂L] is up to 32 times higher as compared to that of [ZnL₂] and [CdL₂]. The replacement of 4-iododipyrromethene ligands in [BF₂L] and [ML₂] by 5,5'-or 4,4'-dibromo-substituted ligands increases photostability of the dyes. The stability of the dyes against UV irradiation substantially decreases in benzene with respect to cyclohexane due to enhancement of polarization of the chromophore systems of dipyrromethene ligands because of their solvation with benzene (π–π-stacking).

4-[(1,1'-Biphenyl-4-yl)oxy]phthalonitrile was synthesized by nucleophilic substitution of the nitro group in 4-nitrophthalonitrile, and its reactions with zinc and erbium salts afforded zinc tetrakis[(1,1'-biphenyl- 4-yl)oxy]phthalocyanine and single- and double-decker erbium complexes. Spectral characteristics of the synthesized compounds were studied.

The structure of the condensation products of D-lactose and D-maltose with sulfanylacetic, 3-sulfanylpropanoic, and 2-sulfanylbenzoic acid hydrazides has been studied ¹H and ¹³C NMR spectroscopy. The condensation products obtained from the disaccharides and sulfanylacetohydrazide and 3-sulfanylpropanehydrazide have pyranose structure in the crystalline state, whereas those derived from 2-sulfanylbenzohydrazide have cyclic 1,3,4-benzothiadiazepine structure in crystal. All condensation products in solutions in most solvents (D₂O, DMF-d₇, DMSO-d₆) exist as equilibrium mixtures of linear and cyclic pyranose and 1,3,4-benzothiadiazepine tautomers.

Zinc sulfide nanoparticles were synthesized in pores of a perfluorosulfonic membrane by ion exchange fixation of Zn²⁺ cations followed by the processing with gaseous hydrogen sulfide. Resulting ZnS particles are X-ray amorphous, have a low density, and are clearly expressed in absorption and luminescence spectra. Features of the nanoparticles optical properties were considered in light of electrons photoexcitation on antibonding orbitals (Zn–S)*.

Ten 1,2,4-oxadiazole fused benzofuran derivatives 11a–11j are synthesized, and their structures are confirmed by ¹H and ¹³C NMR, and mass spectral data. Their anticancer activity against four human cancer cell lines, A549 (Lung), MCF7 (Breast), A375 (Melanoma), and HT-29 (Colon), by the MTT method is tested. The compounds 11b–11d, 11g, 11h, and 11j demonstrate more potent activity than the positive control.

Pyrido[2,3-d]pyrimidine derivatives were synthesized by the reaction of 2-hydrazinopyrido[2,3-d]-pyrimidin-4(3H)-one with different aryl aldehydes and active methylene compounds. Their structures were characterized by spectroscopic methods.

A rapid, efficient and environmentally benign synthesis of novel indole analogs bearing thiazolidinone attached to substituted thiazolyl coumarin scaffolds are synthesized. Conventional and microwave-assisted (MW) approaches are studied. Structures of the products are confirmed by FT-IR, NMR (¹H and ¹³C) and Mass spectra. The in vitro antitubercular and antimicrobial activities are evaluated. Several screened compounds demonstrate promising anti-TB and antimicrobial properties. The structure activity relationship (SAR) study reveal that the compounds containing halogens are most potent. Docking of the potent compounds inside the active site of a target enzyme mycobacterial enoyl reductase (InhA)(PDB code 4TZK) is performed.

In this study, a series of p-aromatic isothiocyanates are prepared by reacting p-aromatic amines with carbon disulphide and further treating with molecular iodine to yield corresponding isothiocyanate derivatives. The structures of newly synthesized compounds are confirmed by IR, NMR, and MS data. Activity of the products against plant pathogenic fungi and bacteria is tested and the structure-activity relationship is approached. p-Nitrophenyl isothiocyanate most efficiently inhibits Rhizoctonia solani and Erwinia carotovora. The order of seven aromatic isothiocyanates antifungicidal activity is following: p-nitrophenyl > p-methoxyphenyl > p-chlorophenyl > p-methylphenyl > p-ethylphenyl > phenyl > p-fluorophenyl. For antibacterial activity, the order was p-nitrophenyl > p-chlorophenyl > p-methylphenyl > p-ethylphenyl > p-fluorophenyl > phenyl > p-methoxyphenyl. The present study indicates that some of the compounds exhibit promising antimicrobial activity and can be used as an alternative to the traditional synthetic fungicides for controlling R. solani and E. carotovora.

The current status of research into the thermal behavior of heterometallic s–d carboxylates that are suitable candidates for single-source precursors of mixed oxides was considered. Emphasis was placed on the thermal stability and conditions of conversion of complexes to mixed oxides The influence of the composition and nature of the precursor on the composition and properties of the resulting mixed oxides was demonstrated.

The current status of research into the thermal behavior of heterometallic 3d–4f carboxylates that are suitable candidates for single-source precursors of mixed oxides was considered. Emphasis was placed on the thermal stability and conditions of conversion of complexes to mixed oxides. The influence of the composition and nature of the precursor on the composition and properties of the resulting mixed oxides was demonstrated.

Complex formation of α-, β-, and γ-cyclodextrins with sulfasalazine in biologically relevant buffer solutions (pH 1.2 and 7.4) was studied. Formation of inclusion complexes of 1 : 1 stoichiometry between the drug and cyclodextrins was revealed. The ionization state of sulfasalazine more strongly affects the complex formation than does the structure of cyclodextrins. Compared with a neutral molecule, sulfasalazine anionic species forms with cyclodextrins more stable complexes, which are essentially stabilized by possible surface interactions.

A brief analysis of the existing definitions of the term “coordination compound” has been carried out and a definition that takes into account the features of this class of chemical compounds has been proposed. The existing systematic IUPAC nomenclature of coordination compounds and its possible use for constructing the names of metal complexes of different types, as well as difficulties associated with this process have been considered.

1-[2-(1H-indol-3-yl)ethyl]-4-acetyl-3-hydroxy-5-phenyl-1H-pyrrole-2(5H)-ones were synthesized by the short heating of a mixture of tryptamine, aromatic aldehyde, and methyl acetylpyruvate followed by stirring at room temperature for one day.