Chemistry Journal of Moldova. General, Industrial and Ecological Chemistry

8-13

Authors: N.Ya. Tsibakhashvili, L. Mosulishvili, E. Kirkesali, T. Kalabegishvili, S. Kerkenjia, M.V. Frontasyeva, Gh. Duca, I. Zinicovscaia

Most powerful primary analytical technique, neutron activation analysis, was applied to study indigenous bacteria, namely, Arthrobacter genera which can be successfully used in detoxification and immobilization of toxic substances. In the present study the effect of Cr(VI) on the elemental content of these bacteria has been examined. The concentrations from 12 to 19 elements such as Na, Al, Cl, K, Fe, Co, Zn, As, Br, Rb, Sr, Sb, Ba, Tb, Th, U were determined in the bacterial cells. The high rate of Cr accumulation in the tested bacterial cells was shown. In bacteria treated with chromate some similarity in the behaviour of the following essential elements − potassium, sodium, chlorine − was observed. Such non-essential elements as Ag, As, Br and U were determined in all bacteria and have to be considered by cells as toxins.

24-27

Authors: Ludmila Kiriyak, Natalia Cecoi, Tatiana Cazac, Mihail Revenco

The polarographic behavior of the complex formed by V(V) and 2,3–dihydroxybenzaldehyde (2,3–DHBA) in the solution containing acetate buffer (pH 5,2) has been investigated. By means of a.c. polarography, chronovoltammetry and other techniques, it has been shown that the electrode process is complicated by the adsorption of 2,3-DHBA and its vanadium complex. The kinetic and adsorption parameters of the electrode process have been determined: adsorption equilibrium constant B= 1,32⋅105 mol-1⋅dm3, the attraction constant γ = 1,2, the maximum surface concentration Гmax = 9,10⋅10-11 mol⋅ cm-2; the share of the electrode surface occupied by one particle of the adsorbed complex S = 1,81 nm2 and the free adsorption energy ΔG = - 39,1 kJ· mol-1.

34-39

Authors: Olga Covaliova

The problem of preventing the heavy metals and other toxic substances release in environment due to the discharges of untreated plating and rinsing solutions is actual from both ecologic and economic point of view. It is crucial to prevent the environmental pollution and uncontrolled losses of resources (metals and other substances). The treatment technologies used today are not always efficient and cost saving and in some cases they may even provoke the secondary pollution of environment. Electrochemical treatment of industrial waste waters is one of the most promising technologies as it implies the same principles as the main technological processes and does not require introducing of chemicals into the treated solution. However, until now this method was given insufficient attention, although there are certain publications in this field [1]. The electrochemical behaviour of some d-metal complexes was studied and discussed from the viewpoint of water treatment requirements. The studies performed in the model plating solutions of Zn, Ni, Cu ammonia and pyrophosphate complexes, polynuclear Cr complexes have shown that the application of conventional reagent waste water treatment methods for such solutions would be inefficient. Examination of potentio-dynamic polarization curves registered in studied solutions have shown, that due to the formation of series of Zn ammonia complexes, alkaline treatment will not ensure Zn removal from such solutions, and application of electrocoagulation treatment method will not be efficient enough. It was also found that in case of Ni-, Crcontaining solutions electrochemical treatment can be used for Cu removal, whereas for the effective Cr(VI) removal the electrocoagulation would be required, which entails the redox processes resulted in the formation of hydroxides. The research has shown that the approach on the heavy metal removal from the used plating solutions may be different depending on the plating bath composition.

44-49

Authors: Boris Găină, Rodica Sturza, Violeta Bejan, Constantin Bodean

The basic objective of this work is studying the content of ochratoxin A (OTA) in grapes, grape juice, and wine. This is an analysis of their origin, the conditions of contamination and ways decontamination, toxiconogenes mushrooms, toxicity, world and European regulations. It was estimated the methods of detection of mycotoxins in wine products. It has examined the contents of OTA in the moldavian juice/wine from different varietals at different stages of winemaking and obtained by different proceeds winemaking.

60-67

Authors: Silvia Melnic, Denis Prodius, Sergiu Shova, Helen Stoeckli-Evans, Yurii Simonov, Alexander Feher, Maria Gdaniec, Constantin Turta

Nine new complexes with the general formula {[Ln2Ba(α-Fur)8(H2O)4]}n, where Ln = Nd3+, Sm3+, Eu3+, Pr3+, Gd3+, Tb3+, Ho3+, Er3+ and La3+; α-Fur ≡ C4H3OCOO, were synthesized and characterized by IR spectra, magnetism, X-ray single crystal and powder diffractions. The X-ray diffraction analysis reveals that all titled compounds are isostructural and possess 1D architecture with Ln ion in an eight-coordination geometry formed by six oxygen atoms from furoate and two oxygen atoms from water molecules. The magnetic behaviour of several synthesised complexes as well as {[Gd2Sr(α-Fur)8(H2O)4]}n was investigated in the temperature range of 1.8-300 K. The magnetic data were interpreted in the HDVV approximation with the exchange coupling constant J = - 0.014 cm- 1 that indicates antiferromagnetic interaction in {Gd2Sr}, whereas a ferromagnetic one J = + 0.007 cm-1 for {Gd2Ba}.

78-81

Authors: Oleg Radul, Alexandru Gudima, Fliur Macaev

New effective synthesis of the chiral chinchoninic acids form (-)-α-pinene has been elaborated. It has been shown that, the considerable increase of the yield and purity of chiral acids is achieved applying the method of under phase transfer catalysis.

86-93

Authors: Oleksandr Shkurenko, Kinga Suwinska, Florent Perret, Katia Sigaud, Antoine Leydier, Said Jebors and Anthony W. Coleman

Diamino-bicycloundecane mono-deprotonates H-calix[4]arene and the solid-structure of the resulting salt has been determined by X-ray crystallography. Two different complexes are present in the structure with the Diamino-bicycloundecane cation held in the calix[4]arene cavity by CH-p interactions. In the packing there is a hydrogen-bonded polymeric chain. Both the complexes formed layered structures with differing inter-layer distances.

100-104

Authors: Anca-Dana Bendrea, Ana-Maria Catargiu and Mircea Grigoras

Mesoporous SBA-15/conducting polymers composites, type SBA- polithiophene, SBA-polyaniline, respectively were synthesized and their physical properties were investigated. Polymers molecules were synthesized by chemical oxidative polymerization inside the pores of the mesoporous material by a post-synthesis process. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, thermal analysis and infrared spectroscopy.

116-117

Authors: Felix Shepel, Diana Shepel, Fliur Macaev

The increase of yield up to 63% of ethyl 5-hydroxy-1,2-dimethyl-1H-3-indolecarboxylate was obtained via the interaction of p-benzoquinone with N-methyl-β-aminocrotone ether in mixture of glacial acetic acid/ethyl acetate.

8-16

Authors: Tudor Lupascu, Pavel F. Vlad, Aculina Aricu, Maria Cocu

This communication deals with the appearance and development of the research in the fi eld of chemistry in the Republic of Moldova; at the beginning - in chemistry sections of Moldovan Branch of the USSR Academy of Sciences and then - at the Institute of Chemistry, founded in 1959. The dynamics of changes in the structure and research subjects is traced. Data are presented concerning the research results in the fi eld of the chemistry of coordination compounds, fi ne organic synthesis, natural products chemistry, physicochemical analysis, quantum chemistry, mineral resources, chemistry of natural water and purifi cation of waste water, the preparation and utilization of active carbons, and ecological chemistry. A detailed account both of basic research and applied investigation is given. The collaboration of our scientists with their colleagues from abroad is considered. Information is presented related to the scientifi c schools at our institute, its guidance and laboratory′s leaders. The scientifi c equipment of the institute is mentioned. The relationship of the institute with higher schools, as well as training of young researchers will be presented.

30-35

Authors: Pavel F. Vlad, Fliur Z. Macaev

This overview deals with the advances in the investigation in the fi eld of organic, bioorganic and natural products chemistry as well as the biologically active compounds in the Institute of Chemistry of the Academy of Sciences of Moldova.

44-55

Authors: Tudor Lupascu, Maria Gonta, Viorica Gladchi

This review details the most important achievements in the fi eld of ecological chemistry and environmental protection, obtained at the State University of Moldova and Institute of Chemistry of the Academy of Sciences of Moldova. The main research directions are described, as well as main scientifi c laboratories and centres of these two institutions.

66-71

Authors: Cristina Dinu, Gabriela Vasile, Liliana Cruceru, Jana Petre

The European Drinking Water Directive (98/83/EC), transposed in Romanian Legislation as Low 458/2002, amended by Low 311/2004, imposes the limit of concentration for metallic elements in water intended for human consumption. The toxic metals arsenic and selenium are among these elements and the limit value is 10 μg/L. In the paper there are presented the working conditions for determination of As and Se from drinking water using modern techniques based on the fl ow injection-hydride generation with the inductively coupled plasma atomic emission spectrometry (FIAS-ICP-EOS). The analyses were performed on Optima 5300 DV Perkin Elmer equipment with FIAS 400 Flow Injection System, Perkin Elmer type. For the hydride generation two types of solution were used: 10% (v/v) HCl as a carrier solution and 0.2 % NaBH4 in 0.05%NaOH solution as a reducing agent [1]. The treatment step of the samples and standard solutions consisted in reducing with mixed solutions of KI and ascorbic acid in acidic condition (HCl) for As and only with HCl and high temperature for Se [2,3]. The paper contains the characteristic parameters of the methods, such as: low detection limit, quantifi cation limit, repeatability, precision, recovery, which were evaluated using Certifi ed Reference Materials for each element.

75-78

Authors: Vasile Rusu and Aliona Vrinceanu

Studies of the sorption capacity towards Cu2+ ions of diatomite from the Ghidirim location of RM, as well as of the extracted clay phase are presented. Separated clay fraction from diatomic material is clean enough, and especially is rich in montmorillonite. Maximum sorption capacity for studied clay fraction is achieved by rising the temperature of calcination treatment up to 200oC. At higher temperatures the lattice of montmorillonite is contracted and its sorption capacity towards Cu2+ ions decreases strongly.

84-89

Authors: E.N. Kornilova, N.I.Kornilov, O.N Vasiltseva

Mineral waters of Russia, the CIS countries (Ukraine, Belarus, Moldova, Armenia, Azerbaijan, Georgia and Uzbekistan) and EU (Germany, France, Italy, Spain and some East European countries) carried to Chloride- Hydrocarbonate type have been investigated in this work. The analytical dependences connecting, entered by authors, characteristic parameters of structure of waters (

97-102

Authors: Loredana Vacareanu (Stafie), Virgil Barboiu, Daniel Timpu, Mircea Grigoras

A Schiff base macrocycle with persistent rhomboidal shape was synthesized in excellent yield through [2+2] condensation reaction between (R,R)-1,2-diaminocyclohexane and 4,4’-diformyltriphenylamine. The dimeric macrocylic structure was proved by electrospray ionization mass spectrometry (ESI-MS), 1H-NMR, and FTIR spectroscopy. The complexation properties were evidenced by UV absorption.

111-117

Authors: O. I. Gona, N. V. Stolyarchuk, Yu. L. Zub, and N. A. Yaroshenko

Mesoporous silicas with the thiourea functional group ≡Si(CH2)3NHC(S)NHC2H5 have been synthesized by monotemplate and bitemplate route (bitemplate is cetylpyridinium chloride as micelle-forming surfactant and monoethanolamide of saturated n-aliphatic acid as non-micelle-forming surfactant). The infl uence of a number of factors on mesoporous silicas structure has been studied: alkoxysilanes and surfactants concentration, and as well as the nature of medium in hydrothermal treatment of mesophases. The optimum conditions under which functionalized mesoporous silicas have possessing highly ordered hexagonal structure have been found. The surface area of mesoporous silicas synthesized using optimum bitemplate solubilization composition reaches 1055-1350 m2/g and sorption volume and pore diameter are 0.75-0.95 cm3/g and 2.5-2.9 nm respectively.

123-128

Authors: N. N. Gorinchoy, B. Dobrova, M. Yu. Gorbachev, G. Munteanu and I. Ya. Ogurtsov

The present work is devoted to the theoretical study of the activation of the acetylene molecule coordinated in the [Pt(PPh3)2C2H2] complex. By means of DFT calculations it is shown that the geometrical and electronic characteristics of the C2H2 are essentially changed due to its coordination. The subsequent detailed analysis of the molecular orbitals (MO) of the active valence zone of this complex allows one to make important conclusion that this activation is being realized mainly due to the orbital back donation of 5d-electronic density from one of the occupied MOs of the complex [Pt(PPh3)2] to the unoccupied antibonding π*-MO of C2H2.