Chemistry Journal of Moldova. General, Industrial and Ecological Chemistry

21-26

Authors: Maria Sandu, Anatol Tarita, Raisa Lozan, Natalia Zgircu, Elena Mosanu, Tatiana Goreacioc, Alexandru Zlotea, Anna Comarnitchi, Iulia Sidoren, Sergiu Turcan, Adrian Tarita

The research results have marked a low value of the self-purification capacity for Beleu Lake water, between 0.12 and 0.19, which is of 1.2-2 times smaller than the one from Prut River (0.25), correlating positively with the values of BOD5, COD-Cr and the time of biochemical oxidation of ammonium ions. The evolution of stage NH4+(NH3) → NO2- in the process of nitrification in lake water in November 2014 takes place about 25 days and the process NO2- → NO3- is more than 35 days, the duration about 2 times higher than in lake water stages from 2015 and 2.8-3.0 times higher than that of the model with water from Prut River.

33-38

Authors: Haruka Dote, Hiroki Yasuhara, Satoru Nakashima

Several types of crystals having different color appeared in the synthesis of assembled complex of mixed crystals with three metals. [H2(bpp)][M(NCS)4] changed to 1D chain polymer (M(NCS)2(bpp)) by releasing HNCS from the cation and anion in a reaction vessel.

50-54

Authors: Elena Secara

Synthesis of new drimane and homodrimane lactams, derivatives of octahydro-1H-benzo[d]azepine and octahydro-1H-benzo[c]azepine, from norambreinolide is reported. These compounds were prepared by Beckmann rearrangement of the corresponding ketooximes.

61-68

Authors: Rajaa Khedir Al-Yasari

DFT method has been carried out to study the substitution effects of NO2 group on the electronic (ionization potential, electron affinity, electronegativity, hardness, softness and electrophilicity index) and IR spectral properties of biphenyl and derivative molecules by using the B3LYP functional and the 3-21G basis set, as well as the optimization structure. The calculated values of HOMO and LUMO energies, as well as predicted by ChemBioDraw program 1H and 13C NMR spectra for the studied compounds are in a good agreement with experimental data.

74-85

Authors: Abdulfatai Siaka, Adamu Uzairu, Sulaiman Idris, Hamza Abba

Thermodynamic and kinetic mechanisms of forming six semicarbazones have been investigated computationally by DFT B3LYP method. All the reactions proceed via two transitions and include two consecutive steps: bimolecular and unimolecular. The computed transition steps have varying equilibrium constants values, enthalpy of activation and Gibbs energy of activation, depending on the semicarbazone involved.

91-96

Authors: Daryna Haliarnik, Oleg Petuhov, Olga Bakalinska, Tudor Lupascu, Mykola Kartel

The catalytic activities of nanoporous carbon materials, their modified forms and enzyme catalase was determined by calculation of Michaelis constants according to the kinetics of substrate decomposition. It is found that the catalytic activity of studied samples correlated with surface basicity and presence of quaternary nitrogen groups in structure.

26-32

Authors: Petru Spataru, Igor Povar, Elena Mosanu, Ana Trancalan

The influence of substrates on the oxidation of reduced toxic forms of nitrogen in river water was investigated by laboratory modelling. Granite and expended clay accelerate the oxidation of ammonium and nitrite ions from 2 to 4 times. The presence of calcium carbonate in water hinders the oxidation of nitrogen in the polluted water.

48-53

Authors: Masahiro Mikuriya, Kenta Ono, Shun Kawauchi, Daisuke Yoshioka, Ryoji Mitsuhashi, Makoto Handa

Mixed-metal complexes constructed from dinuclearruthenium(II,III) carboxylates and tetracyanidoplatinate(II), [{Ru2(O2CCH3)4}2Pt(CN)4]•2H2O (1) and [{Ru2{O2CC(CH3)3}4}2Pt(CN)4]•2H2O (2), were synthesized and characterized by elemental analysis and IR and UV-vis spectroscopies.

58-61

Authors: Lidia Lungu

The synthesis of new nitrogen-containing drimane and homodrimane sesquiterpenoids in cycle B is reported. A comparative study of the microwave (MW) assisted synthesis of drimenone versus classical conditions has been done. The drimanic and homodrimanic oximes were prepared on the base of ketones derived from commercially available sclareolide. The drimanic amine was obtained by reduction of corresponding oxime with LiAlH4. The structure of novel compounds was confirmed using IR, 1H and 13C NMR analyses.

68-76

Authors: Diane Fournier, Liviu Ciobanu, Donald Poirier

Tyramine sulfamate was linked to the trityl chloride resin and this polymeric support used to introduce two levels of molecular diversity by formation of peptide bonds. A dual cleavage strategy next generated in a sequential way (without resin split) two types of compounds (phenol and arylsulfamate derivatives), which are therapeutically attractive types of compounds.

89-91

Authors: Ivan Osipov

Procymidone was chosen as the model compound and its phototransformation was followed under sunlight irradiation. The main photodegradation products on silica is 3,5-dichloroaniline and 3,5-diclorphenilisocyanate. The use of ammonium ferric citrate enhances the degradation of the procymidone.

99-108

Authors: Mohammad Taghi Taghizadeh, Morteza Vatanparast, Saeed Nasirianfar

Supplementary material contains Tables S1 to S9 and Figures S1 to S4.

20-24

Authors: Tatiana Mitina, Nadejda Bondarenco, Diana Grigoras, Elena Botizat, Tudor Lupascu

This paper dwells upon the influence of sodium ions on experimental results regarding the concentration of strontium ions in waters with a high content of sodium ions by emission flame photometry and atomic absorption spectroscopy. The metrological characteristics of both methods are evaluated.

33-41

Authors: Ecaterina Covaci, Gheorghe Duca, Rodica Sturza

In young wines potassium hydrogen tartrate is always present in supersaturating concentration and crystallizes spontaneously. The aim of this study is to obtain kinetic parameters, which explain the stability of young wines during the stabilization treatments. The kinetic and equilibrium parameters were evaluated and discussed. According to the obtained experimental results, the optimal regime for production and stabilization of young wines has been established.

46-51

Authors: Mihail Iacob

Hematite nanoparticles were prepared by a procedure consisting in sonication of μ3-oxo trinuclear iron(III) acetate of composition [Fe3O(OOCCH3)6(H2O)3]NO3∙4H2O, {Fe3O}NO3, as iron source, in strong basic conditions followed by thermal treatment at 600˚C. The formation of the hematite was confirmed by IR spectroscopy, X-ray powder diffraction and Raman spectroscopy while the shape and size of the nanoparticles and their agglomeration were evidenced and estimated on the basis of the images taken with TEM technique.

57-63

Authors: Natalia Mashcenko, Angela Gurev, Galina Lupascu, Elena Gorincioi

The paper relates on the discovered bioactivity of the iridoid glycosides extract (IGE) from Linaria genistifolia (L.) Mill, namely its stimulating influence on the resistance of the winter wheat Odesschi 51 plant to the caused by the F. oxysporum and H. avenae pathogenic fungi root rot. 1H and 13C NMR characteristics of 5-O-allosylantirrinoside in Py-d5 are for the first time presented. Structures of two conformers of the IGE main component, 5-O-allosylantirrinoside in D2O and Py-d5 solutions are proposed, based on the experimental NMR evidence and molecular modeling studies.

71-75

Authors: Lilia Anghel

In this study, the protonation states of ionizable groups of human lactoferrin in various conformations were investigated theoretically, at physiological pH (7.365). These calculations show that the transition of the protein from a conformation to another one is accompanied by changes in the protonation state of specific amino acid residues.

84-88

Authors: Dumitru Sirbu

57Fe Mӧssbauer spectra were recorded for 1'-terpyridine ferrocenecarboxylic acid and [bis(1'-terpyridine ferrocenecarboxylic acid) Fe(II)]2+ in the temperature range 7 – 293 K. The temperature dependence of the Quadrupole Splitting, Isomer Shift and Debye-Waller factor are discussed. The Debye temperature, θD, for the iron nuclei in the investigated compounds was determined.

95-103

Authors: Oleg Petuhov

This paper reports on the preparation of activated carbon from walnut shell. Orthogonal array experimental design method was used to optimize the preparation of activated carbon with phosphoric acid by using microwave treatment. The optimization parameters were: microwave power, activation time, phosphoric acid concentration and particle sizes of nut shells. Thermal analysis of the intact and impregnated with phosphoric acid walnut shells was used for the simulation of activation process. Activated carbon with the optimal parameters was obtained, being characterized by gas adsorption method and scanning electron microscopy.

113-115

Authors: Diana Shepel, Tatiana Goreacioc, Tudor Lupascu, Mihail Filippov, Maria Rusu

This communication is devoted to the elaboration of a new optimal technique of infrared spectra registration of activated carbons in potassium bromide pellets. Authors investigated the dependence of the intensity of the least overlapping infrared bands of activated carbons on the conditions of preparation, recording of the spectrum, and the degree of homogenization with potassium bromide.

14-18

Authors: Raluca Anamaria Cristache, Ana Maria Budu, Petronela Spiridon, Viorica Vasilache, Ion Sandu

The authentication of cultural heritage assets is a complex process of scientific investigation which regards obtaining information about: author (painter), the period when it was made, the owners and other data related to the main contexts of their evolution in time (routes travelled). In fact, the identification of specific archaeometric features is aimed, in determining the materials composition and the patina, then the study of artistic techniques and technology used in the making process of a work of art. Latest serves to define the patrimonial elements and the role of the artifact in time. The expertise of old panel painting icons requires an interdisciplinary approach, correlating the artistic style with technique and materials used. In this regard, the specific techniques of microscopy and spectroscopy are very useful tools for determining the composition of structural elements and their deterioration / degradation state. This work presents a comparative study of the paper used in the preparation layer of three icons painted in Russian style. As an analysis techniques were used the micro and macro photography assisted by Optical Microscopy (OM), SEMEDX and micro-FTIR. Based on the experimental data obtained, it was found that the icons belong to the first half of the 19th century.

26-31

Authors: Silvea Pruteanu, Petronela Spiridon, Viorica Vasilache, Ion Sandu

Old icons, especially those involved in liturgical rituals are affected in time by external agents factors (temperature, humidity, light, pollution, microbiological attack, abrasion etc.), resulting changes of the appearance and of the structural integrity, dirt deposits, altered varnish and painting layer, cracks, material loss etc. In order to remove the dirt deposits, there are used cleaning systems with dry wiping, vacuuming, scraping, washing with organic solvents, ion exchange solutions, polyelectrolyte, surfactants, and so on, by enzymatic systems or by laser pyrolysis. The last two processes being considered aggressive and highly invasive, although they do clean very well adherent dirt deposits, which strongly degraded the varnish to total blackening (the iconographic image cannot be seen). Based on the literature in the field, regarding the nature of the materials used during the painting process and of the types and structures of the deposits, a series of alcoholic solutions of different concentrations were made, as such or basified, which were compared with ecologic synergic systems based on organic uncolored vegetable juices and decoctions from dried plants. The cleaning effectiveness was done by visual analysis and CIE L*a*b* reflection colorimetry, space proposed by the CIE (International Commission on Illumination) in 1976, was used. This technique permitting to determine by color deviations the critical point where the patina and polychromes layer.

41-51

Authors: Оlga Covaliova, Alexandr Kоshev, Valery Varentsov

The main regularities of the electroactive components distribution, polarization and local current density within the depth of the three-dimensional fl ow-through electrode have been studied using the calculation method, in dependence on the overall current density, electrode thickness and degree of its compression, solution fl ow velocity through the electrode, initial concentration of Fe(III) ions in the solution and electrodes brand.

58-61

Authors: Tudor Lupascu, Mihail Ciobanu, Victor Botan

Processes of removal of divalent ions of iron and manganese and hydrogen sulfide from groundwater at various pH values and temperature were studied. Obtained results have been used in order to elaborate a process of groundwater purification from the mentioned pollutants. The use of elaborated process for natural water leads to the decrease of the content of iron, manganese and hydrogen sulfide below the maximum allowable concentrations.

67-73

Authors: Ana Popusoi, Nicanor Barba, Aurelian Gulea, Jenny Roy, Donald Poirier

3-(4-(Dimethylamino)phenyl-1-(4-isothiocyanatophenyl)prop-2-en-1-one was obtained from the corresponding N,N-dimethylthyoureas by elimination of dimethylamine at heating with gaseous hydrogen chloride in chloroform and 1-(4-isothiocyanatophenyl)-3-(pyridin-2-il)prop-2-en-1-one by treating 1,1-dimethyl-3-(4-(3- (pyridin-2-il)-acryloyl)-phenyl)thyourea with acetic anhydride. The difference in the reactivity of the groups >C=O and NCS in the synthesis with hydrazine hydrate and its derivatives allows the synthesis of some 1,3-disubstituted propenones with thiosemicarbazide groups (4- and 1,4-disubstituted) in good yields. From 4-substituted thiosemicarbazides and 2-formilpyridine thiosemicarbazones were obtained. In the case of some derivatives, the propenone group in the reaction with hydrazine hydrate allows the formation of pyrazole derivatives. All obtained compounds were investigated for antileukemia activity. It was found that this activity is more pronounced for thiosemicarbazide derivatives with two pyridine nuclei at concentrations 10-5-10-7 mol/L.

80-89

Authors: Natalia Gorinchoy

The pseudo Jahn-Teller effect is employed to explain the origin of distortions of carbonyl fluoride, diazene and ketene molecules in the lowest singlet and triplet excited states. The ground state and the excited electronic states of considered molecules were calculated by ab initio SCF CI method with the use of the 631G-type basis set. The corresponding pseudo Jahn-Teller coupling constants are estimated by fitting the ab initio data for the adiabatic potential curves of the molecules to the general formula, obtained from the vibronic theory. With these data an explanation of both the larger instability of the triplet excited states as compared with the singlet ones and the elongation of the corresponding bond distances in the excited states is obtained.

99-106

Authors: Lilia Anghel

The multitude of physiological processes in which the binding of iron ions takes part makes its mechanism worth investigating. The multiple sequence alignment method was applied to investigate the structure similarities of five lactoferrin X-ray crystallographic structures and outline the differences and similarities between lactoferrin and serum transferrin. The results of this study provide useful insights into the mechanism of iron-binding of lactoferrin protein molecule.

14-32

Authors: Madalina Zanoaga, Fulga Tanasa

This article offers an overview of some contemporary antimicrobial agents used as functional finishing for textiles intended for biomedical applications. It reviews only synthetic agents, namely quaternary ammonium compounds, halogenated phenols, polybiguanides, N-halamines, and renewable peroxides. These agents can be divided into several groups according to their mechanism of antimicrobial activity, toxicity, durability and ecological acceptability. Examples of commercial antimicrobial products are presented herein, as well as the corresponding finishing methods.

37-41

Authors: Nikolay Kornilov, Elena Kornilova, Elena Stepanenko

In the article we give the results of comparative analysis of the composition of the Eurasian hydromineral resources and we implement the assessment of their impact on the physiological condition of an organism of the person according to biochemical studies of venous blood. Processing of initial data on the composition and properties of mineral waters chloride-hydrocarbonate, sulphate-hydrocarbonate and chloridesulphate types and venous blood are made using the method of mathematical modeling, developed by the authors of this article. It is shown that in the balneological impact hydromineral resources on the body hemoglobin and oxygen in the blood increases, glucose decreases, and acid-base pH shifts to high alkalinity.

53-58

Authors: Laura Bulgariu, Igor Cretescu, Dumitru Bulgariu, Matei Macoveanu

The adsorption on non-conventional and low-cost materials for removal of toxic heavy metals and oil products from aqueous media has become important in the last years, because is an efficient and cost-effective alternative compared to traditional chemical and physical remediation, and also other decontamination techniques. The good efficiency, minimization of secondary (chemical or biological) wastes and low cost of adsorbent materials, are only few main advantages of adsorption that can be used for the removal of such pollutants in high volumes of aqueous solutions, being thus more adequate for large scale applications. In this paper, are presented the adsorptive characteristics of a low-cost material that are abundant in our region, namely: Romanian peat moss from Poiana Stampei (Romania), for the removal of different toxic heavy metal ions (Pb(II), Hg(II), Co(II) and Ni(II)) and oil products from aqueous media. The experiments have concerned the influence of several experimental parameters (initial solution pH, adsorbent dose, initial heavy metals concentration, contact time, and temperature) on the heavy metals and oil products removal efficiency. The most important conditions for desorption of heavy metal ions from loaded-materials, required for their regeneration are also presented.

74-79

Authors: Carmen Zaharia, Victoria Fedorcea, Adrian Beda, Victor Amarandei Augustin Muresan

The paper presents some data from our laboratory-setup experiments of homogenous oxidative processes with hydrogen peroxide (i.e. advanced Fenton oxidation processes) applied for Remazol Rosso RB dye-containing aqueous systems, especially textile effluents. Therefore, some different operating parameters (including pH, concentration of dye, H2O2 and ferrous ions, oxidation time, temperature, stirring regime, among its) were tested for determination of the best performance in effluent discoloration and dye removal, meaning the optimal values of each studied parameters for highest discoloration or dye removal. For an effluent loaded with 50 mg/L Remazol Rosso RB dye, there were applied these optimal values that correspond to > 97 % discoloration efficiency performed with 88.24 mM H2O2, 0.18 mM FeSO4, at pH (5.16), temperature of 19-20°C, continuous stirring regime (30 rpm) and minimum 25-30 minutes of homogenous advanced oxidation treatment. If there are not used additional chemical reagents for pH adjustment (minimization reason of treatment operating cost), the performance of this oxidative treatment is closed to above mentioned efficiency by after a higher oxidation time (> 90 min). These results are encouraging and sustain this oxidative process application and optimization for reducing the environmental impact of effluent discharging directly in different natural aquatic receptors and compliance with admissible limits imposed by environmental legislation as well.

85-92

Authors: Maria Gonta, Gheorghe Duca, Vera Matveevici, Larisa Mocanu

Advanced oxidation methods of organic compounds lead to their partial mineralization and increase of the adsorption process efficiency on the surface of oxidized activated carbon. We have studied the oxidation process using model solutions containing mixture of dye direct brown (DB), ethylene glycol (EGL) and sodium lauryl sulfate (SLS) under the action of Fenton reagent, in the presence and absence of UV irradiation or under the action of electric current (in the electrochemical cell). The same studies were performed by replacing the iron (II) ion with titanium dioxide. We have found that the degree of oxidation and mineralization increases by photocatalytic oxidation and decreases the concentration of organic compounds. Due to the oxidation of dye molecules and other auxiliary components, by strong oxidation ability of free OH* radicals, which evolve to the formation of carbon dioxide, water and low molecular organic compounds (alcohols, ketones, organic acids) are forming. The decrease of the concentration of mixture of organic compounds (for the values of COD-Cr) depends on the nature of catalysts and the presence of electric current. The degree of oxidation is greater in the presence of iron (II) ions than in the presence of titanium dioxide after oxidation of the mixture of organic compounds with hydrogen peroxide in model solutions. This is explained by the fact that UV irradiation increases the concentration of free OH* radicals as iron ions further decompose hydrogen peroxide, but in the presence of titanium dioxide, the leading band electrons are accepted by free OH* radicals, converting these radicals to ions, as shown in the mechanism by Garcia J., et al. This leads to a decrease of the concentration of OH* radicals in model solution and reducing the effect of oxidation, respectively. On the contrary, in the presence of electric current electrons are accepted by the electrode, and the OH* radicals concentration does not decrease, but increases, and this leads to the enhancement of the oxidation effect and mineralization of organic compounds.

100-105

Authors: Masahiro Mikuriya, Nobuyuki Nagao, Satoshi Kurahashi, Atsushi Tabuchi, Seiki Tomohara, Motohiro Tsuboi, Daisuke Yoshioka, Hiroshi Sakiyama, Akira Fuyuhiro

Mixed-valent tetranuclear MnIIMnIII 3 complex with 1,3-diamino-2-hydroxypropane-N,N’,N”,N”’-tetraacetic acid (H5dhpta), Ca2[Mn4{μ-OHO}(dhpta)2(CH3COO)2], was synthesized and characterized by elemental analysis, IR and UV-vis-NIR spectroscopy, and temperature dependence of magnetic susceptibilities (4.5—300 K). Single-crystal X-ray crystallography revealed a trapezoid tetranuclear core with μ-(OHO), μ-alkoxido, μ-acetato bridges. Magnetic data analysis showed considerable antiferromagnetic interactions among these four manganese atoms with J(MnIIIMnIII) of –35.02 cm–1, J’(MnIII(MnII)-MnIII) of –4.82 cm–1 , and J”(MnII-MnIII) of –4.61 cm–1.

112-116

Authors: Irina Davidenko

Azobenzene polymer compositions are extensively studied now due to wide perspectives of their applications in optoelectronics and information technologies. Some possibilities of modification of their properties by chemical methods are analyzed in the present work. These methods allow to improve information characteristics of the media. Electrooptical effect is investigated and possibilities of polarization sensitive holographic recording is demonstrated in copolymer octyl methacrylate with incorporated azo dyes and its complex with Co ions.

123-127

Authors: Inna Melnyk

Current paper focuses on the analysis of influence of main factors (stages of the synthesis, the ratio of the reacting components, the order of their introduction, the concentration of water and ammonia, the synthesis temperature) on the morphology, size and content of functional groups of aminosilica nano- and submicrospheres. The recommendations for the synthesis of particles with predetermined properties were done. It is shown, that the ratio of the reacting components mainly affects the content of 3-aminopropyl functional groups and the temperature of the hydrolytic polycondensation reaction - the size of the particles.

132-135

Authors: Gabriela Ciobanu, Constantin Luca, Octavian Ciobanu

In this study, the porous hydroxyapatite-fi lled cellulose acetate scaffolds were prepared via dry-wet phase inversion method by dispersing hydroxyapatite nanoparticles in the polymeric matrix. The calcined hydroxyapatite prepared by wet precipitation method has the crystal size smaller than 50 nm. The unfi lled and hydroxyapatite-fi lled cellulose acetate scaffolds have an asymmetric structure consisting of two layers, the dense top layer (active layer) supported by the porous sub-layer (substructure). The cross-sectional SEM images revealed that hydroxyapatite nanoparticles were well dispersed in the cellulose acetate matrix.