Chemistry Journal of Moldova

DOI: dx.doi.org/10.19261/cjm.2015.10(1).01

Graphical Abstract:  This review presents a synthetic transformations of ent-kaurane diterpenes, covering various aspects of the chemical and microbiologically transformations of native ent-kaur-16-en-19-oic acid, namely, its reactions via COOH groups, double bonds and rearrangements of the carbon skeleton, what we offer a wide range of natural and synthetic derivatives potentially biologically actives and convenient synthon for their synthesis.

DOI: dx.doi.org/10.19261/cjm.2015.10(1).02

Graphical Abstract:  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.

DOI: dx.doi.org/10.19261/cjm.2015.10(1).03

Graphical Abstract:  The following factors which can improve the process of coagulation were studied: (i) the influence of stirring speed during coagulation and (ii) the influence of the concentration of the coagulant solution added in the process of coagulation. The coagulation process was studied on raw water of the Prut River. Application of the recommended procedure contribute to the reduction of the coagulant dose, the contact time, the aluminum concentration in water and the expenses for water treatment.

DOI: dx.doi.org/10.19261/cjm.2015.10(1).04

Graphical Abstract:  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.

DOI: dx.doi.org/10.19261/cjm.2015.10(1).05

Graphical Abstract:  The present work was undertaken to study the effect of the treatment temperature on the potassium bitartrate stability and composition of young wines. The thermodynamic parameters, namely ∆G°, ∆H°, ∆S° were calculated to predict the nature of potassium hydrogen tartrate (KHT) precipitation. According to the achieved results, the exothermal nature and thermodynamical feasibility of KHT precipitation in young wines were established. Based on thermodynamics, negative ∆G°, ∆H° values and positive ∆S° value give a spontaneous KHT process at lower temperatures.

DOI: dx.doi.org/10.19261/cjm.2015.10(1).06

Graphical Abstract:  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.

DOI: dx.doi.org/10.19261/cjm.2015.10(1).07

Graphical Abstract:  A lanthanum(III) cyanoacetate complex  {[La2(CNCH2COO)6 (H2O)4]∙H2O}n (1) was synthesized and characterized by X-ray single-crystal analysis. The complex 1 exhibits one-dimensional coordination polymer structure. Cyanoacetate ligands coordinated in the bidentate bridging and tridentate-chelating bridging modes. The cyano-group of ligand is not coordinated to the lanthanide ion.

DOI: dx.doi.org/10.19261/cjm.2015.10(1).08

Graphical Abstract:  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.

DOI: dx.doi.org/10.19261/cjm.2015.10(1).09

Graphical Abstract:  Described synthesis of 5-bromo substituted oxindoles linkages in spirocyclic butenolides exhibit relatively dependence of the structure-reactivity relationships of N-substituted isatines, dimethyl acetylenedicarboxylate and triphenylphoshine. The study of the stereochemistry of the atom C(2) of the spiro compounds was also unambiguously confirmed by single crystal X-ray analysis. 

DOI: dx.doi.org/10.19261/cjm.2015.10(1).10

Graphical Abstract:  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.