Bulletin of the Taras Shevchenko National University of Kyiv. Chemistry
"Bulletin of the Taras Shevchenko National University of Kyiv. Chemistry" is a peer-reviewed open access periodical scientific journal. ISSN: 1728-2209 DOI: https://doi.org/10.17721/1728-2209 Subject Area: Chemistry Registered: by the National Council of Television and Radio Broadcasting of Ukraine. Decision No. 1089 dated March 28, 2024. Media Identifier: R30-03802. The magazine is included in the list of scientific subject area journals of Ukraine (category B) in the subject area 102 Chemistry (order of the Ministry of Education and Culture No. 130 of March 17, 2020). Founder: Taras Shevchenko National University of Kyiv Legal address: 60, Volodymyrska Str., Kyiv, Ukraine, 01033. Postal address: 64/13, Volodymyrska Str., Kyiv, Ukraine, 01601. Publisher: Kyiv University Publishing and Printing Center (14, Taras Shevchenka Blv., off. 43, Kyiv, Ukraine, 01030). Deputy Head: Nataliya MELNYCHUK (+38(044) 239-3222; vpc_div.chief@univ.net.ua) Coordination Center for the publishing of scientific journals “Bulletin of Taras Shevchenko National University of Kyiv” (series) Head: Ganna Kharlamova Editorial Address: Hetman Pavlo Skoropadsky St, 12, 01033, Kyiv, Ukraine; chemistry.bulletin@knu.ua Year of foundation: 1958 (in 2009, 2011-2012, 2021-2022 the publication of the journal was suspended). Languages of Publication: Ukrainian, English. Periodicity: once a year Current: 60 № 1 (2025)
Київський національний університет імені Тараса Шевченка
KINETIC'S INVESTIGATION OF METHACRYLIC MONOMERS BASED ON 2-STYRYLQUINOLINE
Polymethylmethacrylate is widely use material in optics due to its atmosphere resistance, chemical stability, good mechanical properties, transparency and light transmission. Due to these properties, PMMA is often used as a polymeric matrix for creating photosensitive polymers and polymers with nonlinear optical (NLO) properties. Materials with NLO properties can be made by introducing moleculas of chromophores into the polymer chain. There are two fundamentally different ways of doing this. The first is to create composite material where the chromophore is a dispersed phase and is introduced into the system as a "guest". In the second case, the chromophore is introduced into the polymer chain covalently, and can be included in the side and the main chain. Studies of polymers containing NLO chromophore in the side chain have shown a number of advantages: better orientation of the chromophores under the action of an electric field; relaxation processes are much slower; increasing time and thermal stability; increasing the glass transition temperature of the polymer. Based on present knowledge we decided to design new methacrylic polymers with styrylquinoline chromophore in side chain. The polymerization ability of the new monomers for free radical homopolymerization was investigated kinetically by using dilatometric method. It was found that new 2-styrylquinoline containing monomers are able to homopolymerization with high conversions (63–83 %). The polymerization was carried out in DMF using 2,2´-azobisisobutyronitrile as initiator at 80°C in argon atmosphere. The products of polymerization were characterized by 1H NMR spectroscopy. It was installed that all new monomers have bigger speed of polymerization (Ksum= 1.36–8.33×103 l/mol×s) then methylmethacrylate (Ksum= 0.5×103 l/mol×s), phenylmethacrylate (Ksum= 1.1×103 l/mol×s) and similar to polymerization of 2-methyl-8-oxyquinoline methacrylate (Ksum= 3.28×103 l/mol×s). It was found that speed of polymerization increases with increasing electron donating power of substitute in para-position of the aromatic ring. It has been proven that presence of electron acceptor group reduces speed of polymerization.
8-methacryloxystyrylquinoline, styrylquinoline-containing monomers, polymerization kinetics
Copyright (c) 2019 О. Харченко, канд. хім. наук, В. Смокал, канд. хім. наук, О. Крупка, канд. хім. наук, О. Колендо, д-р хім. наук https://creativecommons.org/licenses/by/4.0
INFLUENCE OF MACROCYCLIC COORDINATION COMPOUNDS OF COPPER (III) ON THE PRODUCTIVITY OF VIRUSINDICATED SPRING WHEAT PLANTS
Viral plant diseases cause crop losses and deterioration in product quality. One of the most widespread and harmful for wheat is Wheat streak mosaic virus. In this work, effect of two cooper (III) macrocyclic coordination compounds on growth and development of spring wheat plants infected with Wheat streak mosaic virus is investigated. The macrocyclic complexes have been obtained by template synthesis by reaction of oxalyl dihydrazide with carbonyl compounds (cyclohexanone or formaldehyde in the presence of copper(II) salts and atmospheric oxygen in aqueous solution. Identity and purity of the isolated compounds was confirmed by elemental analysis and powder X-ray analysis. The structure of the complexes was established by means of single crystal X-ray analysis. Aqueous solutions of both complexes can exist indefinitely long at ambient conditions without any signs of destruction. It was found that compounds increased plant weight and its dry matter content depending on the application method. In two variants, the seeds were sprouted on distilled water and treated with 0.05% solution of the studied complexes and in two other variants the seeds were soaked in 0.1% solutions of the same complexes, and then sprouted at 22°С. A positive effect on non-specific plant resistance upon foliar treatment with sodium-containing compound has been detected. Seed soaking with solutions of complex compounds result in overall positive impact on wheat development. The lithium and potassium counter cation-containing compound increased the weight of the ground part and root system, while compound with sodium counter cation - dry matter content in the roots in both healthy and virus infected plants. This indicates about the stimulation of resistance processes in wheat plants to WSMV-infection.
Copyright (c) 2019 Л. Міщенко, К. Криницька, В. Павленко, А. Дуніч https://creativecommons.org/licenses/by/4.0
BEHAVIOR OF ACID HYDROLYSIS IN BLOCK COPOLYMERS COMPRISING POLYACRYLAMIDE AND POLY(ETHYLENE OXIDE)
Polymeric micelles self-assembled from amphiphilic block copolymers have been intensively investigated as nano-carrier systems for tumor-targeted drug delivery. Diblock copolymers PEO-b-PAAm (DBC) and thriblock copolymers PAAm-b-PEO-b-PAAm (TBC) contained biocompatible chemically complementary polyacrylamide and poly(ethylene oxide) formed micellar structures in aqueous solutions which have hydrophobic complex "core" formed by the hydrogen-bonded PEO/PAAm chains and hydrophilic "corona" of the surplus segments of PAAm blocks. The ability of DBCs and TBCs to bind the anticancer drug doxorubicin was established. This opened the new prospects for using such copolymers as nanocontainers for toxic and poorly soluble drugs. Successful implementation of DBC and TBC micelles for drug delivery requires the presence a special vectors, particularly galactose, in the micellar "corona". Such vectors can recognize corresponding receptors on a cellular surface, interact with them, and penetrate into the intracellular space by the endocytosis pathway. In order to introduce the galactose vectors into DBC or TBC micelles, the corona forming PAA blocks have to contain the corresponding active groups, such as –OH, –COO–, –NH2. Therefore, the methods of DBCs (TBCs) functionalization are particularly important since it allows to input the necessary saccharides and also to expand the applications of micellar nanocarriers to encapsulate and delivery of both the drug substances and genetic materials. In the present work, the polymer-analogous conversion of DBCs and TBCs by the acid hydrolysis of PAAm blocks at 50°C was studied. Kinetic investigations of the hydrolysis reaction of DBCs (TBCs) in comparison with pure PAAm were performed by potentiometric titration. It was established that the process of acid hydrolysis of diblock- and thriblock copolymers depends on the blocks length and occurs more intensive in the block copolymers which have longest PEO and PAA chains. The reasons for this phenomenon are discussed. The fact is that hydrolysis of DBCs samples develops efficiently in comparison with TBCs ones attributed to the steric obstacles which appears in TBCs micelles because of their more complicated structure.
Copyright (c) 2019 Л. Куницька, Т. Желтоножська https://creativecommons.org/licenses/by/4.0
THERMOSTABILITY OF POLYSTYRENE BY STYRYLQUINOLINE CONTAINING METHACRYLATES
It's known that polystyrene is one of the most widely used plastics. The materials based on it are used in almost all branches of engineering and human's daily life. Therefore, the creation of new highly effective thermal stabilizers for polystyrene remains as the actual task of polymer chemistry. Combining fragments of basic industrial monomer with the modifiers in the polymer matrix provides the ability to control performance properties of obtained materials. Investigation of thermostabilitive action of new styrylquinoline containing methacrylic monomers on polystyrene have been described in this work. Polystyrene and copolymers based on styrene and new methacrylic styrylquinoline containing monomers were synthesized by free radical thermoinitiated polymerization. 2,2´-Azo-bisisobutyronitrile (1 mass per cent) was used as initiator. Styrylquinoline monomers (3 mol per cent) were added to styrene for making modified samples. Polymerization was carried out by heating of reactants in ethyl acetate during 16 hours. Polymers were precipitated in isopropanol and dried at vacuum. The impact of such dopants – 2-[2-(4-methoxyphenyl)ethenyl]quinolin-8-yl 2-methylpropyl-2-enoate (М1), 2-(2-phenylethenyl)quinolin-8-yl 2-methylpropyl-2-enoate (М2), 2-[2-(4-nitrophenyl)ethenyl]quinolin-8-yl 2-methylpropyl-2-enoate (М3) were investigated. Thermostability of polystyrene and modified samples styrene:M1, styrene:M2, styrene:M3 were studied by dynamic thermograviametric analysis. It was shown that destruction of polystyrene with dopants M1-M2 starts at 41–42°С higher than reference polystyrene prepared at the same conditions and polystyrene of brand STYRONE (Switzerland). Sample with dopant M3 begins destruction with lower speed than reference polystyrene. First one loses 20 % of weight at 347°С while reference polystyrene loses 50 % of weight. It means, that dopant M3 can act as retarder of thermal destruction of polystyrene. It was found that new monomers have thermal stabilizing effect after its covalent introducing and can act as effective inhibitors of thermodestruction of polystyrene in the air.
styrylquinoline containing monomers, methacrylic monomers, polystyrene, thermostabilization
THE EFFECT OF THE SUBSTITUENT NATURE IN THE AZOBENZENE CHROMOPHORES ON DIFFRACTION EFFICIENCY OF POLARIZATION HOLOGRAMS
The films of polymeric composites containing monomers of azobenzene dyes or azobenzene lateral groups chemically bonded to the main polymer chain demonstrate photoactive properties, and can be used in electrooptical light modulators and in recording media (RM) for polarization holography. Photoinduced optical anisotropy (PIA) appears under influence of linearly polarized light caused by the processes of trans-cis-izomerization of the azobenzene groups. This process is determining for application of the considered materials as RM for polarization holography. The films of polymeric polarization sensitive media based on a copolymer of styrene with nonyl methacrylate doped with azobenzene-type dyes with different electron-acceptor substituents are obtained in this work. In the films of copolymer the holograms of the plane wave front were registered for parallel and orthogonal orientations of polarization vectors of the object and reference light beams. Their photoelectrophysical, in particular photodielectric, and information properties are investigated. It was established, that when the mutual orientation of the recording beams changes from the orthogonal to parallel orientation the diffraction efficiency of the holograms increases in the case of using azo dye with the maximum number of auxochromic substituents in the molecule. The effect of the diffraction efficiency dependence on the chromophores structure is connected with the deepening of dye color. The photo-induced optical anisotropy in the films appears due to a change of the concentration ratio of trans- and cis-isomers of azobenzene dye fragments. This conclusion is confirmed by the photodielectric measurements data, namely, by the negative sign of the photodielectric effect, observed experimentally in the investigated thin film structures. It was shown, that investigated compositions can be used as information media for polarization holography.
azobenzene dyes, electron-acceptor substituents, polarization holography, recording media, diffraction efficiency
Copyright (c) 2019 Н. Давиденко, д-р физ.-мат. наук, И. Давиденко, д-р физ.-мат. наук, В. Кравченко, д-р хим. наук, Е. Мокринская, канд. хим. наук, В. Павлов, вед. инж., С. Студзинский, канд. хим. наук, В. Тарасенко, инж. 1 кат., Л. Тонкопиева, канд. хим. наук https://creativecommons.org/licenses/by/4.0
SORPTION PRECONCENTRATION AND DETERMINATION OF ANTIMONY AND TELLURIUM ON MODIFIED SILICA GEL
Antimony and its compounds are widely used in industry, making it one of the priority pollutants of air and the aquatic environment. Excess of antimony is selectively concentrated in a thyroid gland, a liver, a spleen. The manifestation of the toxic effect of antimony is a variety of impaired functions of the human body, so the content of this element in drinking water normalizes is at the level of 5 μg/l. Recently, tellurium has also been increasingly the subject of research by analyst chemists. Tellurium is a biologically active element and its concentrations in the environment are strictly regulated. According to sanitary rules and regulations, the maximum allowable concentration of tellurium in drinking water is 0.01 mg/l. The article is devoted to the elaboration of solid-phase reagents based on the quaternary ammonium salt (QAS) immobilized on silica gel and to the development on this basis of sorption-spectrometric and visual test-methods of the determination of Sb(III) and Te(IV). The mechanism of the interaction between QAS immobilized on silica gel and the anions iodide complex of antimony and tellurium was studied. It was found that it proceeds by the ion-associative mechanism. Conditions of sorption preconcentration of anionic complexes of elements were optimized. For the quantitative sorption of antimony (III), the weight of the sorbent is 0.020 g and the volume of the solution is 25.0 ml. Under these conditions, the anionic complex is sorbed by 98 %. The maximum concentration ratio is 1.25 l/g. The sorption equilibrium in the system is established in 20 minutes. For the quantitative extraction of tellurium (IV), the optimal weight of the sorbent is 0.050 g and a solution volume of 25.0 ml. Under these conditions, the degree of sorption reaches about 80 %. The maximum concentration ratio is 0.4 l/g. The sorption equilibrium in the system is established in 15 minutes. The influence of foreign ions on the extraction degree of the investigated elements, and also on the magnitude of analytical signal, was studied. Sorption-spectrometric and visual test-methods of the determination of Sb(III) and Te(IV) in pharmaceutical preparation "Antimonium tartaricum" and "Tellurium Metalicum"
solid-phase reagents, immobilization, silica gel, ionic associates, solid-phase spectrophotometry, test-methods, Sb(III), Te(IV), pharmaceutical preparations
Copyright (c) 2019 В. Верба, канд. хім. наук, О. Запорожець, д-р хім. наук, І. Кухаренко, студ., Є. Кульбака, студ. https://creativecommons.org/licenses/by/4.0
3-(2-PYRIDIL)-5-(2-HYDROXYPHENYL)-1,2,4-TRIAZOL AS A REAGENT FOR FLUORIMETRIC DETERMINATION OF MICRO-AMOUNTS OF ZINC
The development of new fluorescent reagents for determination of trace amounts of zinc in biological samples is an actual issue. Efficient reagents should characterized by high hydrophobicity, low sensitivity to media acidity and intense fluorescence in the long-wavelength region of the spectrum. Therefore, the using of a rigid π-conjugated molecule of 3-(2-pyridyl)-5-(2-hydroxyphenyl)-1,2,4-triazole as a fluorescent probe for the determination of zinc micro-quantities in biological samples is considered as a rational choice. 3-(2-pyridyl)-5-(2-hydroxyphenyl)-1,2,4-triazole is a highly hydrophobic ligand (logP=3.0±0.1). Dissociation of the protonated nitrogen atom in the pyridine cycle of the ligand occurs at pH = 4, рКа1= 3.98±0.05. The pKa2 value is equal to 8.74 ± 0.03 and corresponds to the dissociation of the N-H group of the triazole fragment. The absorption spectrum of the ligand solution in DMSO is characterized by two bands with maximum at 272 nm and 320 nm due to intraligand π-π * transitions. The values of the molar absorption coefficient for these bands are 1.18·104 l ·mol-1·cm-1 and 1.36·104 l·mol-1·cm-1, respectively. Two bands at 402 nm and 535 nm are also observed on the fluorescence spectra of the ligand. The high fluorescence intensity in the long-wavelength region of the spectrum indicates the promising use of this ligand as an analytical reagent at a creation of new fluoresce techniques. 3-(2-pyridyl)-5-(2-hydroxyphenyl)-1,2,4-triazole as chelating ligand can form two complex compounds in DMSO solution with composition ML and ML2. Complex formation is accompanied by the appearance of a third absorption band in the visible regions of the spectrum at 440 nm (ε440≈ 6,5·103 l ·mol-1·cm-1) due to LMCT transitions. In addition, the complex formation leads to fluorescence quenching. Developed fluorescent techniques for determination of zinc quantities in a sample of hair and in a tablet of vitamins "Duovit" are characterized by satisfactory precision and accuracy. The range of zinc concentrations determining in the hair sample is 71–286 μg/g, Sr=0,033 (n=3, P=0.95). The zinc content that was found in the "Duovit" tablet is well correlated with the declared content. This indicates the good selectivity of ligand in relation to the accompanying microelements.
1,2,4-triazole derivatives, fluorescence, zinc determination
Copyright (c) 2019 В. Старова, канд. хім. наук, Д. Хоменко, канд. хім. наук, Р. Дорощук, канд. хім. наук, Р. Лампека, д-р хім. наук https://creativecommons.org/licenses/by/4.0
SYNTHESIS OF THE OXIDIZED FORM OF DITHIENO-TTF BY ELECTROCRYSTALLIZATION
General principles of the electrocrystallization technique in application to organic molecules are shown, as some historical background. Based on this, we were able to rationalize main variables in the experiment which are needed in order to get crystals of the oxidized form, that are suitable for further applications such as for example single crystal x-ray diffraction analysis or conductivity measurements. The biggest impact comes from such factors as choice of solvent and supporting electrolyte, which influence directly the solubility of both the starting compound and its oxidized form. Purity of all components is also paramount. In order to avoid formation of by-products, experiment is usually performed in a sealed U-shaped electrochemical cell with a glass filter between the anodic and cathodic compartments and under inert atmos-phere such as argon or nitrogen. Other parameters considered here, such as temperature of the solution and intensity of the current, help to fine-tune the result, but have less impact on whether the crystallization will occur at all. It is also critical to maintain both parameters at con-stant values in order to obtain high quality single crystals. Galvanostatic oxidation mode is more favourable comparing to the potentiostatic as it allows steady rate of oxidation by providing fixed intensity of the electrical current and subsequently more stable rate of crystal grows, alt-hough potentiostatic mode or alternating current can be used to grow bigger amounts when quality of the single crystal is less important. Fur-ther we used this approach to electrocrystalize previously obtained by our group dithieno-TTF, based on the exTTF scaffold. According to the literature cyclic voltammetry data, dithieno-TTF undergoes reversible single-wave two electron oxidation to form bis-cation similar to classic exTTF, but in our case only radical-cation salt was obtained in a form of shiny, dark-red, needle-like single crystals. This could be attributed to its extremely low solubility and corresponding formation of the kinetic product, which correlate well with relatively fast crystallization just with-in 3 days. Another possibility is a comproportionation reaction involving the starting neutral molecule and oxidized dication.
Copyright (c) 2019 С. Крикун, І. Левков, Т. Єгорова, З. Войтенко https://creativecommons.org/licenses/by/4.0
SYNTHESIS OF PHENYLACETYL MIDA BORONATES BY OXIDATIVE CLEAVAGE OF VICINAL DIOLS
A synthetical approach to acyl(N-methyliminodiacetyl)boronates starting from 1-substituted alkenylboronates has been developed. A comparison of different methods of oxidative cleavage of an α-borylated C-C bound was made. It was found, that the best results can be obtained by sequential osmium tetroxide-catalyzed dihydroxylation of an alkene moiety followed by cleavage of the obtained vicinal diol. The cleavage procedure takes place at 0 °C in homogeneous conditions (solution of periodic acid in THF) and it is complete in 10 minutes (more prolonged contact with an oxidant solution results in degradation of the target compound). On the other hand, using of ruthenium tetroxide-based reagents results in overoxidation with simultaneous loss of boron moiety. Potassium permanganate protocols leads to the α-borylated-α-hydroxyketone, which is prone to further oxidation. Although 1-alkyl-vinylboronates react smoothly with 3-chloroperbenzoic acid to give corresponding oxiranes (without cleavage of C-B bound), the latter ones are stable toward action of sodium meta-periodate or periodic acid. The results were shown on the model compound – phenylacetyl MIDA boronate. Precursor of this compound, namely, Z-2-(N-methyliminodiacetylboryl)-1-phenylbut-2-ene was prepared in four steps, starting from common-use reagents with 32% overall yield. Thus, the new approach allows acetyl MIDA boronates to be prepared just in 6 linear steps. It is remarkable, that mild and homogeneous conditions of the oxidation step permit to carry out this transformation on gram scale. A preliminary investigation of these substances stability towards common methods of working up and purification procedures was made. It was found, that phenylacetyl MIDA boronate and preceding diol, both are stable to storage at ambient conditions (tightly closed vessel, ambient temperature) at least for one month, showing no changes in its NMR spectra. Also, these compounds are stable to extractive work up with NaHCO3, Na2S2O3 and diluted acids. Stability toward chromatography on silica, prolonged contact with water or alcohols is limited. Structures and purity of compounds in this work was established by 1H, 13C – NMR and HPLC-analyses.
Copyright (c) 2019 Є. Івон, В. Ле, З. Войтенко https://creativecommons.org/licenses/by/4.0
INFLUENCE OF SURFACTANTS ON THE FLUORESCEIN FLUORESCENCE PROPERTIES
The use of fluorescence as an analytical signal makes it possible to reduce the limits of detection of analytes. The study of spectral properties of luminophores is important for the development of new methods for analyzing various objects. The use of micellar systems enables to increase quantum yields by 2–10 times and fluorescence intensity by 3–80 times and reduce the limits of detecting analytes by 1–2 orders of magnitude. Organized media based on surfactants influence on the fluorescence of luminescent indicators and their complex compounds due to changes in their microspheric solution of their photophysical characteristics, aggregate state and microprobe nature. Cationic surfactants occupy a special place among cytotoxicants. Low levels of maximum permissible concentrations of cationic surfactants require the use of sensitive analytical methods that combine simplicity and availability with reliability and expressiveness. Known chemical and microbiological methods for the determination of cationic surface-active antiseptics, disinfectants and preservatives characterize by complexity and labor intensity and are not suitable for the operational control of their concentration in places of local use. Therefore, the purpose of the work was to study the influence of various types of surfactants on the fluorescence properties of fluorescein to develop a method for determining the content of ethonium. The influence of surface-active substances of different types on the fluorescence properties of fluorescein was investigate. The anionic surfactant almost does not effect on the intensity of the dye signal. Nonionic surfactant leads to a gradual decrease in the fluorescence intensity of fluorescein. The most visible influence was observe with adding into the solution cationic surface-active substances. There is harsh intensity decrease of the dye fluorescence with subsequent exit to the "plateau" in the system of fluorescein-cetylpyridinium chloride. The cationic surfactant ethonium works the same. Received results will laid in the basis of the method development of ethonium determination in the medical drugs.
Copyright (c) 2019 В. Кловак, С. Лелюшок, С. Куліченко, О. Запорожець https://creativecommons.org/licenses/by/4.0
ITO ELECTRODES MODIFIED WITH MnO2/SiO2 FOR THE DETERMINATION OF HYDROGEN PEROXIDE
Nanostructured transition metal oxide nanoparticles possess a catalytic activity to hydrogen peroxide. Manganese dioxide particles are one of the promising and available modificators of the electrode surface. Nanostructured MnO2 deposited onto the surface of the electrode enhances the electron transport from the H2O2 molecule to the surface. Thus selectivity and sensitivity of H2O2 detection can be improved. There are a lot of different methods of the impregnation of manganese dioxide particles onto electrode surface. An electrophoretic deposition is one of the most simple and rapid. By adjusting the electrodeposition parameters, particles of different sizes or films can be obtained. A simple and novel hydrogen peroxide sensor based on layer-by-layer assembly of MnO2 nanoparticles and SiO2 film on the ITO electrode was developed. For this purpose MnO2 nanoparticles were electrodeposited on the surface of ITO electrode from MnSO4/CH3COOK solution. The electrochemical characteristics of the modified electrodes were investigated by cyclic voltammetry. The presence of MnO2 on the surface of modified electrode was indicated by the appearance of clear oxidation-reduction peaks of Mn(IV)/Mn(III,II) at E=0,65 V in the electrolyte solution in contrast to unmodified electrode. Optimization of measurement parameters such as the amount of MnO2, applied potential and pH value were studied in details. Under the optimum conditions, the calibration curve for H2O2 determination using modified electrode was linear in the range from 1×10−4 to 1×10−3 mol/dm3 with a detection limit of 0,09×10−4 mol/dm3 (S/N = 3). The linear rang for non-modified electrode was from 1×10−3 to 1×10−2 mol/dm3 with a detection limit of 1,8×10−4 mol/dm3 (S/N = 3). The modified ITO electrode was characterized by higher current than non modified ITO as a result of increasing of electroactive surface area and catalytic effect of electrodeposited MnO2. For the stabilization of MnO2 particles and protection of the electrode surface from impurities, the ITO/MnO2 was covered by thin silica film. The selectivity of H2O2 determination at ITO modified with MnO2/SiO2 was better than at ITO especially in the presence of ascorbic acid which is oxidized at the same potential as H2O2. The oxidation current of ascorbic acid was much higher than H2O2 at non-modified ITO in contrast to ITO modified with MnO2/SiO2. The developed ITO electrode modified with MnO2/SiO2 is a perspective element of amperometric sensor for the detection of hydrogen peroxide.
electrodes based on indium and tin oxides
Copyright (c) 2019 А. Ковалик, О. Тананайко https://creativecommons.org/licenses/by/4.0
DESIGN AND SYNTHESIS OF MOLECULAR TWEEZER BASED ON 3-HYDROXYFLAVONE FOR THE DETECTION OF ATP
Adenosine 5'-triphosphate (ATP) is known as a universal energy source and signaling mediator in numerous biological processes. Among the methods for its determination, molecular fluorescence probes occupy leading positions due to high sensitivity and selectivity. Recently we have shown that 31 of 33 tested flavones and quinolones of various structures give fluorescence response and can be effectively applied as the probes in aqueous solutions for detection of ATP in 1–50,000 μM range of its concentrations. To increase response parameters of a probe in respect to ATP we have synthesized N,N'-(butane-1,4-diyl)bis(2-((2-(4-(dimethylamino)phenyl)-3-hydroxy-4-oxo-4H-chromene-6-yl)oxy)acetamide, the molecular tweezer composed of two flavonol units connected by active linker. On our idea, being equipped by two planar platforms, the tweezershould demonstrate increased affinity and selectivity to ATP in a result of increased number of hydrogen bonds and increased stacking interactions. Having two NH-amide groups the amino acid linker will form hydrogen bonds with the phosphates of ATP, increasing the portion of probe-ATP complex population in the reporting conformation.In the four-step synthesis of this molecular device, starting from methyl 2-(3-acetyl-4-hydroxyphenoxy)acetateand N,N-dimethylaminobenzaldehyde, the conditions for the reaction of one-pot chalcone formation and its oxidative heterocyclization in the presence of an organic base were found, which resulted in the isolation of a target flavonol- amino acid derivative with high yields. We suggest that atmospheric oxygen was an oxidizer in this process. The obtained derivative was converted intotarget compound by dual condensation with 1,4-butane diamine.
flavonol, molecular tweezers, ATP, oxidative heterocyclization
Copyright (c) 2018 О. Бугера, асп., А. Нетребчук, студ., В. Пивоваренко, д-р хім. наук https://creativecommons.org/licenses/by/4.0
COLLOID-CHEMICAL PATTERNS OF SORPTION OF PALLADIUM (II) ON PHYTOSORBENTS
The colloid-chemical patterns of sorption of palladium (II) on phytosorbents have been studied. It was found that the kinetics of sorption depends on the concentration of palladium (II) in the solution. When the concentration increases, the time of the establishment of the sorption equilibrium increases. Kinetic curves are best described by a pseudo-second order model throughout the range of concentrations studied.The correlation coefficient in the pseudo-first order equation at high concentrations of palladium (II) in the solution has a value close to 1.This feature may indicate that, at low concentrations, the chemical interaction between the metal ion and the functional group of sorbent prevails.At the same time, at high concentrations, internal diffusion also contributes.Thus we have two types of surface groups: "fast" – are on the surface of the sorbent and "slow" – located in the deep layers of the sorbent, access to which is complicated.To corroborate this assumption, the palladium (II) sorption isotherms were constructed on the surface of the phytosorbent at different times of the phase contact.With increasing time of phase contact increases sorption capacity.An increase in temperature leads to an increase in sorption capacity and a decrease in the time of the establishment of sorption equilibrium.This influence of temperature is probably due to the fact that the diffusion of metal ions is accelerated and in the chemisorption immediately, both "fast" and "slow" groups of sorbent are involved.The experimental isotherms of sorption are analyzed using the theoretical models of Langmuir and Freundlich adsorption.It was established that the isotherms of adsorption of palladium (II) on the surface of the phytosorbent are best described by the Langmuir model.The Freundlich model is not suitable for describing the palladium adsorption (II), since the experimental points do not lie straight, and the correlation coefficient has low values.It has been shown that phytosorbent exhibits a good kinetic property and has a high sorption capacity in relation to palladium (II).
electronic nose, probabilistic neural network, identification, cooked sausages
Copyright (c) 2018 Р. Горда, мол. наук. співроб., О. Циганович, канд. хім. наук https://creativecommons.org/licenses/by/4.0
БАБИЧЕВ ФЕДІР СЕМЕНОВИЧ (ДО 100-РІЧЧЯ З ДНЯ НАРОДЖЕННЯ)
Виповнюється 100 років із дня народження видатного хіміка-органіка, відомого фахівця в області хімії гетероциклічних сполук, заслуженого діяча науки та техніки, лауреата Державної премії України, академіка НАН України, доктора хімічних наук, професора Федора Семеновича Бабичева (28.02.1917 — 28.04.2000). Усе творче життя, педагогічна й адміністративна діяльність Ф.С. Бабичева пов'язана з хімічним факультетом Київського державного університету імені Т.Г. Шевченка, студентом якого він став у 1936 році та закінчив його в 1944 році. У стінах цього університету він пройшов шлях від студента, завідувача хімічного складу до декана факультету.
Copyright (c) 2017 В. Іщенко https://creativecommons.org/licenses/by/4.0
MODEL CALCULATIONS OF THERMODYNAMIC PROPERTIES OF LIQUID ALLOYS IN Cu–Lu AND Fe–Lu SYSTEMS
Model calculations of the wide range of thermodynamic properties of binary liquid alloys of iron with lutetium and cuprum with lutetium were carried out using our previously obtained data on partial and integral enthalpies of mixing in these systems. The ideal associated solution model was used to obtain the thermodynamic values. Obtained via ideal associated solution model values of Gibbs energies and excess Gibbs energies of binary liquid alloys of lutetium with iron and cuprum can be used to provide calculations of thermodynamic properties and phase diagrams of multicomponent Fe- (Cu-) and Lu-contained alloys. It is shown that ideal associated solution model is the effective instrument of modelling of thermodynamic properties of the alloys for which noticeable negative deviations of ideal solution behavior are observed due to considerable component interaction in liquid state. Liquid alloys of the investigated systems are characterized by the existence of the short range order of the type of chemical compound. Rather high values of mole fractions of associates obtained during IASM calculations lead to this conclusion. Despite the fact that each phase diagram of investigated systems is characterized by its own set of compounds the curves of integral ebthalpies of mixing in these systems are characterized by similar concentration dependences and can be reproduced using the same set of associates (MeLu and Me2Lu). This fact may indicate a similar character of component interaction in liquid alloys of Cu–Lu and Fe–Lu systems.
thermodynamic properties of liquid alloys
Copyright (c) 2017 Н. Головата, Н. Котова, Н. Усенко https://creativecommons.org/licenses/by/4.0
GAS SENSITIVE SEMICONDUCTOR NANOMATERIALS FOR CREATION OF HYDROGEN SENSORS
Co-precipitaion method and sol-gel technique were used to prepare semiconductor microcrystalline and nanosized SnO2/Sb2O5 and Со/SnO2/Sb2O5 (0.15 wt.% Sb) materials aimed to create high sensitive hydrogen sensors. Morphology and phase composition of the obtained samples were studied by SEM, TEM and XRD methods. It was found that microcrystalline SnO2/Sb2O5 material with particle size of 1–30 µm was obtained by a co-precipitation method and nanosized SnO2/Sb2O5 material with particle size of 5–25 µm (an average size – 12 nm) was obtained by a zol-gel method. Only cassiterite phase was detected for both microcrystalline and nanosized materials. Sensitivity measurements of the sensors were carried out with using of air-hydrogen mixtures in the concentration range of 40 – 1145 ppm Н2, and dynamic characteristics (response time and relax time) were evaluated for 40 ppm Н2 at different heater power consumptions – 0.25 and 0.35 W. To increase sensitivities of the sensors, cobalt oxide, a known catalyst for hydrogen oxidation, was added to the resulting SnO2/Sb2O5 materials. It was shown that the sensors obtained by a zol-gel method demonstrate more significant sensitivity to hydrogen concentration in comparison with the sensors obtained by a co-precipitation method. It is probably associated with a higher surface area of the nanomaterial that agrees with its smaller particles as compared with the particles of the microcrystalline material. The Co-containing sensors based on the nanosized SnO2/Sb2O5 material are established to reveal higher sensitivity to Н2 than microcrystalline Co/SnO2/Sb2O5 sensors. The Co-containing sensors based on the nanosized SnO2/Sb2O5 material were found to have better dynamic characteristics than microcrystalline Co/SnO2/Sb2O5 sensors. The sensitivities increase and the response and recovery time decrease were found for both sensor materials at increasing of the sensors heater power consumption. The obtained results can be explained with different degree of energy surface heterogeneity of the used materials. The sensor response time is determined by the time of dynamic equilibrium establishment of the hydrogen oxidation reaction on the sensor surface and the recovery time is determined by the time of desorption of the H2 oxidation reaction products (H2O) from the sensor surface. Because of the processes, the sensor with a gas sensitive layer based on the nanosized material possessing with more homogeneous structure of its surface (according to the obtained TEM data) demonstrates improved gas sensitive properties in comparison with the sensor based on the microcrystalline material. The obtained results concerning the sensitivities to H2 and the dynamic parameters of the created sensors point to possibility of effective usage of the sensors based on the nanomaterial to detect H2 in air in the practice.
semiconductor Со/SnO2/Sb2O5 materials, sensors, hydrogen, sensitivity, response and recovery time.
Copyright (c) 2020 I. Матушко, Л. Олексенко, Н. Максимович, Г. Сколяр, О. Роїк, Г. Федоренко, Л. Луценко, О. Ріпко https://creativecommons.org/licenses/by/4.0
THE INFLUENCE OF Co-Ni/Al2O3 SYSTEMS SYNTHESIS METHOD ON THEIR CATALYTIC ACTIVITY IN THE REACTION OF СО2 METHANATION
The series of Co-Ni catalysts supported onto Al2O3 was synthesized by different methods: nitrate decomposition, citrate decomposition and reduction in the emulsion. All catalysts were tested in the reaction of СО2 methanation. The highest catalytic activity was obtained from the samples of nitrate decomposition series. Co-enriched samples (Со60Ni40, Со80Ni20, Со100) from this series showed 100 % of СО2 conversion at the lower temperature (300°С) compared to other series. Desorption of СН4 (m/z = 16), СН3* (m/z = 15) and СОН* (m/z = 29) particles from the surface of active samples at the high temperature (400–500 °С) was registered with the method of TPD MS. Possibly, the mechanism of СО2 methanation includes the formation of intermediate CHO* compound. A complicate surface structure of Со80Ni20/Al2O3 sample with the high catalytic activity was demonstrated by the scan electronic microscopy. The size range of particles was 10-100 μm and the middle size was 30 μm. XRD analysis of Co80Ni20/Al2O3 та Co60Ni40/Al2O3 samples shoved the presence of carrier phase: corundum (Al2O3), boehmite AlO(OH), cubic γ-Al2O3. Also phases of spinel (Co3O4) and cubic phase of metal (Co, Ni or their alloy) were indentified. Reflections of spinel are wide and low indicating their nanosize. Reflections of metal are narrow and intensive, indicating the large size of metal crystal.
Copyright (c) 2017 О. Іщенко, М. Жлуденко, О. Бєда, А. Дяченко, С. Гайдай https://creativecommons.org/licenses/by/4.0
ANALYSIS OF AMINE HARDENERS FOR ADHESIVE USING pH-METRIC TITRATION IN MICELLAR MEDIA OF SODIUM DODECYLSULFATE
One of the primary tasks in the development of amine hardeners for adhesive and epoxy resins is the control of amino group quantities in their composition. The main parameter that indicates the rate of the polymerization reaction and characterizes the quality of the hardener is the amine number. It is determined by the number of primary and secondary amino groups contained in the hardener molecule, because these functional groups are involved in reactions with epoxy resins. The most common methods of analysis of amine hardeners are mainly based on titration in organic solvents and require a procedure of derivatization of primary and secondary amino groups using formaldehyde and acetic anhydride. The search for a simple, cheap and environmentally friendly alternative to such titrimetric methods is still ongoing. In this paper on the example of industrial samples of polyamide PO-300, polyethylene polyamine (PEPA) and diethylenetriamine (DETA) shows the prospects of using the method of pH-metric titration in water-micellar medium of sodium dodecylsulfate (SDS) to determine the content of primary and secondary amino groups in the adhesive hardeners. According to the developed techniques, working solutions of PO-300, PEPA and DETA were prepared by dissolving their exact mass in 20 ml of 2.0 M SDS solution. The values of PO-300, PEPA and DETA samples were 0.1040 g, 0.0225 g and 0,0200 g, respectively. Titration of the obtained solutions was performed with 0.05 M HCl solution. The percentage of primary amino groups, calculated on the basis of the obtained differential titration curves, is equal to 5,56% for PO-300, 23,6% for PEPA and 31,6% for DETA. The content of secondary amino groups in PO-300, PEPA and DETA samples is 3,03%, 15,0% and 19,6%. Founded amine number for PO-300, PEPA and DETA is well correlated with data declared by the manufacturer and equals to 302, 1381 and 1890, respectively. Unfortunately, it was not possible to establish the presence and quantity of tertiary amino groups in the samples of adhesive hardeners by this technique. The effect of cationic surfactant cetylpyridinium chloride, nonionic Triton X-100 and anionic surfactant SDS on the value of the pH jump of diethylenetriamine (DETA) was also studied. It was found that anionic SDS has the greatest differentiating effect on the acid-base properties of amino groups DETA in comparison with other studied surfactants. At that, the primary amino groups are titrated in the first place.
amino group quantities, amine hardeners, titration, aqueous micellar media.
Copyright (c) 2020 В. Старова https://creativecommons.org/licenses/by/4.0
ENZYMATIC ACTIVITY THE SERIES OF OXIDOREDUCTASES AS INDICATOR OF PROTEINS NATIVE STATE PRESERVATION INTO HYDROTROPE-INDUCED PHASE OF SODIUM DODECYL SULPHATE
Preserving the proteins native nature after their extraction is a strict requirement in immuno-chemical analysis, medical and food industry at receiving concentrates of viruses, bacteria and proteins. Anionic surfactant sodium dodecyl sulfate (SDS) is the most common detergent that is used for extraction and preconcentration of proteins. However, using of SDS solution often leads to denaturation of proteins and loss of their functional activity. Hydrotrope-induced micellar phase of the SDS (SDS-NaCl-H2Sal) is considered as a rational alternative to classical extragens, due to its ability to quantitatively extract of proteins molecules at pH close to the isoelectric point of the protein (pI) and at conditions of their positively charged forms domination (pH ≤ pI). From our point of view, using of the SDS-NaCl-H2Sal phase can provide a stabilization of the native state of proteins after their preconcentration. The objective of the work was to evaluete the possibility of proteins native state preservation after their preconcentration into SDS hydrotrope-induced phase. Peroxidase, catalase and nitrate reductase were chosen as protein model substrates. The change in the catalytic activity of these oxidoreductases in SDS micellar phase was used as indicator of proteins native state preservation. The activity of peroxidase and catalase was determined by the method of permanganametometric titration as the amount of H2O2 that was decomposed under the action of the enzyme. The activity of nitrate reductase was determined spectrophotometrically by the reaction of Griess reagent with nitrite ions formed as a result of the enzymatic decomposition of nitrates. It has been established that the catalytic activity of peroxidase, nitrate reductase and catalase in the SDS micellar phase increases in two, three and four times in comparison with the aqueous solution, respectively. Such rising of oxidoreductases catalytic activities after their preconcentration into the hydrotrope-induced phase of SDS confirms the preservation of proteins native nature.
micellar extraction, hydrotrope-induced phase, sodium dodecylsulfate, proteins, native state
Copyright (c) 2018 А. Зимогляд, студ., В. Старова, канд. хім. наук, C. Куліченко, канд. хім. наук https://creativecommons.org/licenses/by/4.0
FLUORESCENCE CHARACTERISTICS OF FLUORESCEIN AND EOSIN Y SOLUTIONS IN WATER-MICELLAR SURFACTANT MEDIA
The effect of cationic, anionic and nonionic surfactants on the fluorescence properties of fluorescein and eosin Y aqueous solutions has been investigated. It has been found that sodium dodecyl sulfate does not affect the position of the maximum wavelengths of solutions of fluorescein and eosin Y in the study of the effect of an anionic surfactant on the fluorescence emission intensity of dyes. The intensity of the signal of the dye solutions when changing the concentration of anionic surfactant changes little. As the concentration of non-ionic surfactant increases, the fluorescence emission intensity of the fluorescein solutions decreases. In contrast, with increasing concentration of Triton X-100, there is an increase in the signal intensity of solutions of more hydrophobic eosin Y with subsequent access to the "plateau" at СТХ‑100≥5.1 · 10–2 mol/L. The position of the maxima fluorescence emission wavelengths for the fluorescein solutions in the 0‑1.0 · 10–5 mol/L range of concentrations of cationic surfactant cetylpyridinium chloride remain unchanged. The position of the maxima shifts to the long-wavelength region of the spectrum at higher concentrations of CPC. The nature of the position dependence of the fluorescence emission maxima of eosin Y solutions in the presence of cationic surfactants is similar. The effect of fluorescence quenching has also been shown in the study of the influence of organic substances of cationic nature on the signal intensity of fluorescein solutions. It has been shown that the concentration dependence is linear in the 1.0·10‑2–4.0 · 10–1mol/L range of isoniazid molecule concentrations. The data obtained can be implemented in the development of conditions and methods for the determination of pharmacologically active substances of cationic nature by reaction with fluorescein in medicines.
fluorescence, surfactant, fluorescein, eosin Y.
Copyright (c) 2020 В. Кловак, Л. Нечпай, С. Лелюшок, С. Куліченко https://creativecommons.org/licenses/by/4.0
CATECHOLASE ACTIVITY OF A COPPER(II) COMPLEX WITH THE 2-(5-(1,2,4)TRIAZOLE-1-ILMETHYL-1H-(1,2,4)-TRIAZOLE-3-IL)-PYRIDYL
Methods of the synthesis of 2-(5-(1,2,4)triazol-1-ylmethyl-1H-(1,2,4)-triazol-3-yl)-pyridine and a binuclear copper complex are described. The structure of the complex is established by X-ray structural analysis. The complex is a centrosymmetric [Cu2(L)2(NO3)2·2H2O].H2O dimer. The Cu-Cu distance is 4.0408 (3) Å. In the complex the ligand is in a deprotonated state. Due to this, the triazole fragment acts as a bridge between the two metal centers. Copper ions are in an octahedral environment. The equatorial plane is formed by three triazole nitrogen atoms and one pyridyl nitrogen atom. The axial positions are occupied by a water molecule and a nitrate ion. Isotropic patterns corresponding to binuclear copper particles of the [Cu2L2-H]+ composition were registered in the ESI mass spectra of the solution of the [Cu2(L)2(NO3)2(H2O)2]·H2O complex. These data confirm the presence of a binuclear complex in solution. The catecholoxidase activity of the binuclear copper (II) complex based on 2-(5-(1,2,4)triazol-1-ylmethyl-1H-(1,2,4)-triazol-3-yl)-pyridine was studied. The kinetics of model reactions of the catecholase type were investigated by the method of initial velocities using a model substrate of 3,5-di-tert-butyl catechol (3,5-DTBK). At low concentrations of 3,5-DTBK, the dependence of the initial oxidation rate on the concentration of the substrate is linear, which corresponds to the first order of the reaction on the substrate. However, the dependence graph at higher concentrations of 3,5-DTBK is nonlinear and indicates the saturation of the catalyst with the substrate. The form of the dependence of the initial reaction rate on the substrate concentration is explained within the framework of the Michaelis-Menten model, which well describes the behavior of natural metaloenzymes.
1,2,4-triazole, copper(II) complexes, X-raycrystallography.
Copyright (c) 2020 Д. Хоменко, Р. Дорощук, I. Одарич, I. Распертова, P. Лампека https://creativecommons.org/licenses/by/4.0
STRUCTURAL AND SPECTRAL STUDIES OF THE MIXED-LIGAND CATION COMPLEX OF LANTHANUM [Lа(L)2bipy2]BPh4 WITH CARBACYLAMIDOPHOSPHATE (CAPh) TYPE LIGAND AND 2,2'-BIPYRIDINE
A new cationic mixed-ligand complex [Lа(L)2bipy2]BPh4 (where L-= bis(N,N'-diethylamide)(N'-trichloroacetyl)-triamidophosphate anion, bipy = 2,2'-bipyridine) has been synthesized and studied by the means of IR, 1H NMR spectroscopy, thermogravimetric and X-ray structural analyses. Low-frequency shifts of the absorption bands of the carbonyl and phosphoryl groups of phosphorylated ligand in the IR spectra of the complex compared with similar absorption bands in the spectrum of "free" CAPh ligand are Δν(C = O) = 117 cm–1 and Δν(P = O) = 137 cm–1. The analysis of integral signal intensity in the investigated NMR spectra of coordination compounds [Lа(L)2bipy2]BPh4 indicates the molar ratio of ligand : bipyridine : tetraphenylborate anion as a 2:2:1, which corresponds to the proposed structure of the complexes. The compound has been obtained in monocrystalline form. The structure of the complex has been determined by X-ray structural analysis, its ionic structure was proved, and the coordination of two CAPh ligands through the oxygen atoms of the carbonyl and phosphoryl groups was confirmed. Based on the structural data, it was determined that the La3+ ion is octocoordinated (surrounded by four oxygen atoms from two chelated phosphoryl ligands and four nitrogen atoms from two 2,2'-bipyridine molecules). The coordination polyhedron of central ion is interpreted as a square antiprism. Complex cations and tetraphenylborate anions are connected both by electrostatic interaction and by weak intermolecular C – H ∙∙∙ π-contacts between phenyl substituents of BPh4- and molecules of 2,2'-bipyridine. It was established by thermogravimetric analysis that the complex [Lа(L)2bipy2]BPh4 obtained is thermally stable up to a temperature of 150 °C. Significant decomposition of the complex begins at a temperature of 150 °C, occurs in one stage and most intensively continues up to 300 °C. The total weight loss is 78 %.
CAPh ligands, carbacylamidophosphates, lanthanum, mixed-ligand complexes, X-ray structural analysis.
Copyright (c) 2020 М. Стругацька, I. Олишевець, В. Дьяконенко, В. Овчинніков, С. Шишкіна, В. Амірханов https://creativecommons.org/licenses/by/4.0
IODIMETRY-PHOTOMETRIC DETERMINATION of periodate, iodate And bromate In WATER SOLUTIONS
A simple and accurate three-step procedure for sequential spectrophotometric determinations of periodate, iodate and bromate in aqueous media has been developed. At the first stage the determination of periodate is based on the selective oxidation of the excess amount of iodide at pH=4,8 to produce iodine (triiodide), that can be found by spectrophotometric detection (лmax=350 nm). After detecting the analytical signal, iodine is removed from the solution by sorption on the polyurethane foam. In the second stage the determination of iodate is based on the selective oxidation of iodide at pH=3,0 to produce iodine (triiodide), that also can be found by spectrophotometric detection (лmax=350 nm). After detecting the analytical signal, also iodine is removed from the solution by sorption on the polyurethane foam. In the third stage the determination of bromate is based on the selective oxidation of iodide at pH=1,0 to produce iodine (triiodide), that also can be found by spectrophotometric detection (лmax=350 nm). It has been established that the equilibrium in the reaction (ІО4– + 7І– + 8Н+ → 4І2 +4Н2О) is established in 3 minutes at pH=4,8. The equilibrium in the both reactions (ІО3– + 5І– + 6Н+ → 3І2 +3Н2О and BrО3– + 6І– + 6Н+ → 3І2 +Br– +3Н2О) is established in 7 minutes at pH=3.0 and at pH=1,0 respectively. It was found that oxohalogates are quantitatively converted to I2 with ~ 100-fold molar excess iodide at appropriate optimal pH values. Schematically, the determination of IO4–, IO3– and BrO3– in their combined presence can be represented as follows: ІО4– + ІО3– + BrО3– <!-- [if gte mso 9]><xml> <o:OLEObject Type="Embed" ProgID="Equation.DSMT4" ShapeID="_x0000_i1025" DrawAspect="Content" ObjectID="_1830971881"> </o:OLEObject> </xml><![endif]-->ІО3– + BrО3–+ І3– (SP) <!-- [if gte mso 9]><xml> <o:OLEObject Type="Embed" ProgID="Equation.DSMT4" ShapeID="_x0000_i1026" DrawAspect="Content" ObjectID="_1830971882"> </o:OLEObject> </xml><![endif]--> PUF.І2 (sorbent is discarded) + ІО3– + BrО3– <!-- [if gte mso 9]><xml> <o:OLEObject Type="Embed" ProgID="Equation.DSMT4" ShapeID="_x0000_i1027" DrawAspect="Content" ObjectID="_1830971883"> </o:OLEObject> </xml><![endif]-->BrО3– + І3– (SP) <!-- [if gte mso 9]><xml> <o:OLEObject Type="Embed" ProgID="Equation.DSMT4" ShapeID="_x0000_i1028" DrawAspect="Content" ObjectID="_1830971884"> </o:OLEObject> </xml><![endif]--> PUF.І2 (sorbent is discarded) + BrО3– <!-- [if gte mso 9]><xml> <o:OLEObject Type="Embed" ProgID="Equation.DSMT4" ShapeID="_x0000_i1029" DrawAspect="Content" ObjectID="_1830971885"> </o:OLEObject> </xml><![endif]--> І3– (SP), where SF is spectrophotometry in a solution at 350 nm: PUF is the polyurethane foam Based on the data obtained, the model mixtures of periodate, iodate and bromate by sequential iodiometry-photometric method were analyzed. The error of determination in mixtures of each oxo-halogenate did not exceed 5%.
Copyright (c) 2018 О. Трохименко, канд. хім. наук, О. Запорожець, д-р хім. наук, А. Трохименко, канд. хім. наук https://creativecommons.org/licenses/by/4.0
SILICA GEL MODIFIED WITH 1,2-NAPHTHOQUINONE THIOSEMICARBAZONE FOR SORPTION-PHOTOMETRIC DETERMINATION OF MERCURY (II)
A sorption-photometric test method for preconcentration and determination of mercury (II) was developed using silica gel modified with 1,2-naphthoquinone thiosemicarbazone. Modification of silica gel with a reagent was carried out from the chloroform-hexane solution for 3 hours. Pocket photometer was used for the measurement of reflected (transmitted) light from silica modified after sorption of thiosemicarbazonate of Hg(II). The adsorption capacity of the sorbent has been found to be 35 µmol g-1 for 1,2-naphthoquinone thiosemicarbazone. The effects of pH, sorption time, the volume of aqueous solution were studied. In the optimal conditions (pH 3.0; 5 min; 25°C) the extraction recovery of mercury is 90–95%. The range of concentrations of mercury (ІІ) is 50–600 мg L–1, the detection limit (S/N = 3) is 23 мg L–1. The method is tested in the model tap and natural water samples, relative standard deviation for 50 µg L−1 of Hg(II) is below 9.0 % (n = 3). The interference effect of the most common heavy metals in natural water, as Fe (III), Zn (II) and Mn (II) ions were studied. The EDTA solution was added for the binding of these metals, which forms strong colorless complexes with EDTA. We have shown that in the presence of 0,01 M EDTA solution Fe (III), Zn (II) and Mn (II) ions, each up to 500 µg L−1, do not interfere with the determination of mercury (II) at its content of 50 µg L−1. The method can be used for the determination of mercury in the sewage of various industries and natural waters with its high content. The proposed method is inexpensive, simple, fast, and environmentally friendly for the determination of the micro quantities of mercury (II) in the water samples.
modified silica gel, 1,2-naphthoquinone thiosemicarbazone, mercury (II), sorption-photometric test method
Copyright (c) 2018 М. Зуй, канд. хім. наук, С. Дідук, студ. https://creativecommons.org/licenses/by/4.0
ELECTRONIC NOSE AND PROBABILISTIC NEURAL NETWORK USE FOR SAUSAGES IDENTIFICATION
The electronic nose system based on seven quartz-microbalance sensors was used to generate a pattern of the volatile compounds present in sausage samples with different mass content of soy protein isolate (SPI) ranging from 0 to 30% w/w. The original response curve was extracted to two features such as the maximum response value (ΔFimax, Hz) and area values of sensor response curve and time axis surrounded (Si, Hz×s). All parameters subjected to pattern recognition analysis in original, normalised, scaling values and after principal component analysis. In this paper we used probabilistic neural network (PNN) for multiclass discrimination of sausage products. The neural network architecture was optimized for samples discrimination using as input vectors the electronic nose parameters such as Si and ΔFimax. The best classification reliability (95,8%) for model based on dataset of Si in original values obtained with the values of the PNN smoothing parameter σ in the range from 3,6 to 54,0. The classification model built by ΔFimax dataset in original values gave the 100% identification accuracy with the value of the PNN smoothing parameter in the range from 0,2 to 1,0. Furthermore, the different pre-processing techniques applied to datasets led to a slight decrease the prediction performance of the classification models, but the speed of neural network training has increased. This paper presents a novel approach to identification of cooked sausages and determination of soy products mass content using the electronic nose combined with probabilistic neural network. Compared to classical methods, this new approach could represent an alternative and innovative tool for faster and cheaper sausage identification and mass content of soy protein isolate (0, 10, 20, 30% w/w) detection.
Copyright (c) 2018 А. Калініченко, наук. співроб., Л. Арсеньєва, д-р техн. наук, В. Пасічний, д-р техн. наук https://creativecommons.org/licenses/by/4.0
SYNTHESIS OF NEW CHIRAL α-AMINO ACID DERIVED 3,5-DISUBSTITUTED 1,2,4-TRIAZOLES
An enantio pure pyrazine-linked 3,5-disubstituted 1,2,4-triazoles, an amide bond isosteres, were synthesized by ring closure of acylated with L-α-amino acid residues N-acylamidrazone precursors. Pyrrolidine ring opening of methyl esters of (2S)-2-(imino-oxo-dihydro-6H-pyrrolo[3,4-b] (hetero)aryl)alkanoic acid bearing amino acid moiety at endo-N atom of pyrrolidine ring with Boc-protected L-Phe amino acid hydrazide was firstly shown to provide a new convenient method for preparing pyridine or pyrazine derived N-acylamidrazone intermediates in good yields. No cyclic pyrrolopyridines(pyrazines) derivatives as a result of exo-imine group substitution were found as final compounds. Pyrazine-linked 1,2,4-triazoles were successfully synthesized by thermal cyclization of N-acylamidrazone derivatives using microwave-assisted irradiation. However, pyridine-containing 1,2,4-triazoles of this type are not available from corresponding N-acylamidrazones probably due to their high thermo and solvent sensibility. Under reaction conditions they underwent decomposition followed by intramolecular cyclization giving rise starting pyrrolopyridines. (Z)/(E) isomerism of N-acylamidrazone intermediates was studied by means of NMR spectroscopy and quantum chemical calculations. It was found to be dependent on the heterocycle type. A NOE experiment for phenylalanine substituted pyridine-based N-acylamidrazone demonstrated the occurrence of Z and E rotamers due to amide-type isomerism. Theoretical calculations (B3LYP DFT with the standard 6-31G(d,p) basis set) on N-acylamidrazone isomers indicated amide bond isomerism for pyridine-linked N-acylamidrazones and C=N bond isomerism for pyrazine-linked analogues.
azines, triazole, microwave irradiation, amide isomerism, computational study.
Copyright (c) 2016 О. Овдійчук, О. Гордієнко, A. Аро, М.-К. Аверлан-Петі https://creativecommons.org/licenses/by/4.0
Polymers, composites, their components and complexes for application in information tecnologies and biotechnology as well as for medicine and solar energy transfer have been obtained. In particular, new high-resolution photochromic polymer materials with a significant nonlinear optical effect of the third order have been developed. They are perspective for the creation of high-speed optical switches in optical recording and information storage. A new way of recording information based on the generation of the second harmonic with new photochromic polymers has been found. The perspectivity of alken-functionalised poly(phenyl/naphthylmethacrylates) as basic compounds for polarization-sensitive polymeric media was prooved.The chemical modification of polymers by benzenesulfonamide derivatives for biostabilization of plastic masses and providing hydrophilic properties for their surface was carried out. A fundamentally new approach is developed in which processes of energy transfer of excited states in polymer macromolecule to the photostabilaser are used for effective stabilization of polymer materials. Thermostabilized samples of polystyrene with covalently bonded of imidophenylmethacrylates have been developed. The branched copolymers are highly efficient matrices for the synthesis of stable gold, silver, CdS and Au / CdS nanoparticles and copolymers that can be used as nanovectors for the target delivery of highly toxic antitumor drugs. New effective preparations for desinfaсtion of fish nurseries, dressing and hygienic materials, linen and clothes have been developed.
photochromic polymer, optical information recording, photostabilizers, alloying monomers, energy transfer, thermostabilizers, alkene-functionalized polymers
Copyright (c) 2018 О. Колендо, д-р хім. наук, І. Савченко, д-р хім. наук, Л. Вретік, д-р хім. наук, В. Сиромятніков, д-р хім. наук, Н. Куцевол, д-р хім. наук, О. Надтока, канд. хім. наук, Л. Куницька, канд. хім. наук, Д. Вишневський, інж. https://creativecommons.org/licenses/by/4.0
SYNTHESIS OF 3-(2-PYRIDYL)-N-METHYL-1,2,4-TRIAZOLE-5-ACETIC ACID ETHYL ESTER AND THEIR COORDINATION COMPOUNDS WITH Pd(II)
Alkylation of 3-(2-pyridyl)-1,2,4-triazole-5-acetic acid with iodomethane leads to formation of 3-(2-pyridyl)-N1-methyl-1,2,4-triazole-5-acetic acid ethyl ester (L1) and 3-(2-pyridyl)-N2-1,2,4-triazole-5-acetic acid ethyl ester (L2). It was also managed to identify the compound ethyl ester 3-(2-pyridyl)-N2-methyl-1,2,4-triazol-5-yl-α-propionic acid (L3) which is the product of alkylation of L2 in the methylene group. L1-3 were used for synthesis of palladium(II) complexes PdL1Cl2, PdL2Cl2 and PdL3Cl2. The composition and structure of obtained compounds were proposed on the basis of IR and 1H NMR spectroscopy data and elemental analysis. IR spectra of synthesized ligands have a lot in common, due to their structure similarity. As a result of coordination all signals in the IR spectra are shifted besides bands of ester groups. 1H NMR spectra of obtained ligands is bit similar, this is due to their structure. Signals of pyridine ring protons 3-(2-pyridyl)-N1-methyl-1,2,4-trazole-5-acetic acid ethyl ester shifted to 0.11–0.13 ppm in a weak field in compare with izomers. N1–CH3 signals are shifted to lower field than N2–CH3, it can be explained by the influence of negative magnetic anisotropy of pyridine ring. Methyl and methylene signals of ester group are located nearly in the same field in L1–3. Coordination of all ligands occurs through the nitrogen atom of pyridine ring and N4-triazole. In this case all L1, L2 and L3 signals of pyridine protons suffer shift to a low field. Methyl and methylene signals of ester group almost no shifted what indicate that no coordination through oxygen atom.
1,2,4-triazole, palladium(II), IR spectroscopy, NMR spectroscopy
Copyright (c) 2018 Ю. Огороднік, студ., Д. Хоменко, канд. хім. наук, Р. Дорощук, канд. хім. наук, Р. Лампека, д-р хім. наук https://creativecommons.org/licenses/by/4.0
THE SYNTHESIS OF TRIAZOLE CONTAINING ANALOGUES OF SALEN AND VANEN
Facile methods of the preparation of heterocyclic analogues of Salen and Vanen are reported. The azamethine fragments of Schiff bases were replaced by 1,2,4-triazoles. The method of synthesis described may afford to prepare the series of ligand systems with different substituents with high overall yields relatively to the hydrazide. Unlike Schiff's bases, all synthesized compounds are chemically stable and resistant to oxidizing and reducing agents. The molecules are entirely conjugate to the π-systems, which is likely to be reflected in the electronic properties of coordination compounds. Obtained ligand systems could maintain great interest in the synthesis of various transition metal coordination compounds. These could be concluded from the fact that coordination behavior of synthesized ligands is expected to be similar to that is observed for Salen an Vanen type ligands respectively. The resulting compounds have the same donor centers from Salen and Vanen, having a similar planar structure and coordination behavior. All ligands are tetradentate, may leave vacant positions in the coordination sphere of transition metals and form five- and six-membered cycles. The Vanen analogues are capable of forming binuclear complex compounds, since they have internal N2O2 (for coordination with 3d metal ions) and external O2O2 (for exo-coordination of ions of lantanides) donor centers. The compounds obtained are capable of forming coordination compounds with antibacterial, antifungal, anticancer, antioxidant, anti-inflammatory, antimalarial, antiviral activities and also as homogeneous and heterogeneous catalysts in polymerization, epoxidation, hydrosilylation reactions, sensors etc. The analogues were analyzed by NMR and IR spectroscopy.
1,2,4-triazole, Schiff bases, Salen, Vanen, IR spectroscopy, NMR spectroscopy
Copyright (c) 2018 Ю. Бібік, студ., Д. Хоменко, канд. хім. наук, Р. Дорощук, канд. хім. наук, Р. Лампека, д-р хім. наук https://creativecommons.org/licenses/by/4.0
THE SYNTHESIS OF COPPER(II)-CONTAINING 1,2,4-TRIAZOLE COMPLEXES
Methods of the synthesis of the copper(II) containing 3-(2-pyridinyl)-1H-1,2,4-triazole complexes are reported. Systematic studies were devoted to the investigating an importance of triethylamine towards the сomplexation. The various coordination modes that have been observed in complexes were discussed. We noticed the correlations of coordination complexes structure and the metal-ligand correlation. Two mononuclear complexes and one dinuclear complex of a 2:2 composition were obtained. The deprotonation of the ligand in the complex namely [Cu(L)2](H2O)2 was eased by adding triethylamine. The octahedral complex [Cu(HL)2(NO3)](NO3) was synthesized without triethylamine. In excess of ligands, mononuclear coordination compounds formed mostly. By adding the equal to ligand amount of triethylamine we obtained complex in a lower tetragonal symmetry. Deprotonated triazole is the high field ligand, therefore, due to the Jahn–Teller effect, square coordination is more desirable. In all coordination compounds formation of the 5-membered chelate cycle realizes through a pyridine-triazole binding site.The structures of three complexes have been determined by single crystal X-ray diffraction.
1,2,4-triazole, copper(II) complexes, X-raycrystallography
Copyright (c) 2018 Ю. Петренко, студ., Д. Хоменко, канд. хім. наук, Р. Дорощук, канд. хім. наук, Р. Лампека, д-р хім. наук https://creativecommons.org/licenses/by/4.0