Facultatea de Chimie şi Tehnologie Chimică / Faculty of Chemistry and Chemical Technology

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SYNTHESIS AND STRUCTURE OF {M-OXALATO-BIS[ETHYLENEDIAMINETETRAACETATO- BISMUTHATO(III)]}PENTAAMMINETHIOCYANATOCOBALT(III) DODECAHYDRATE, [CO(NH3)5NCS]2[(EDTA)BI(M-C2O4)BI(EDTA)] • 12H2O
(2000) Stăvilă, Vitalie; Gdanec, M.; Șova, Sergiu; Simonov, Iurie; Gulea, Aurelian; Vignacourt, Jean-Pierre
A heterometallic complex of cobalt(III) and bismuth(III), [Co(NH3)5NCS]2[(Edta)Bi(μ-C2O4)Bi(Edta)] · 12H2O, was synthesized and studied by X-ray diffraction analysis. The crystals are monoclinic, a = 12.792(3) Å, b = 9.792(2) Å, c = 22.945(5) Å, β = 92.92(3)°, P(calcd) = 1.970 g/cm3, space group P21/c, Z = 4. The complex has an isle structure composed of [(Edta)Bi(μ-C2O4)Bi(Edta)]4- and [Co(NH3)5NCS]2+ complex ions and molecules of crystallization water. The Edta4- ligand functions as a hexadentate chelating (2N + 40) agent, while the oxalate ion acts as a bridging ligand. The thiocyanate ion is coordinated to cobalt(III) through the N atom, while the cation interacts with the anion via the Bi-S contact (3.571 Å). Hence, the coordination polyhedron of Bi can be regarded as a tricapped trigonal prism. It was shown that thermolysis of the complex proceeds in several stages, viz., the deaquation, deamination, and pyrolysis of its ligands.
STRATEGIA DE UTILIZARE A DEŞEURILOR GALVANICE ÎN MOLDOVA
(2001) Șișcovschi, Gheorghe; Orlova, Nadejda; Borodaev, Ruslan
Problema utilizării deşeurilor galvanice se ridică timp de mulţi ani la diferite niveluri, inclusiv de Guvern (Hot. Nr. 606 din 28 iunie 2000), dar până în prezent în Republica Moldova încă nu există nici un sector tehnologic specializat,cu toate că se cunosc numeroase elaborări brevetate atât la noi, cât şi în ţările CSI sunt destul de multe.
INVESTIGATION OF GEOMETRICAL AND CONFORMATIONAL ISOMERS OF COBALT(II) BIS(DIPHENYLACETATO)-BIS(G -PICOLINATE) BY DYNAMIC NMR SPECTROSCOPY AND MOLECULAR MECHANICS
(2001) Novițchi, Ghenadie; Cecal, Alexandru; Gulea, Aurelian
Cobalt(II) bis(diphenylacetato)-bis(γ-picolinate) is synthesized and its geometrical and conformational isomers are investigated using dynamic NMR and molecular mechanics methods. The complex in the solution is shown to exist as cis and trans isomers, which are detected at 263 K in the course of a slow intermolecular ligand exchange. At T < 223 K, the intramolecular rotation of the phenyl radicals about the -O2C-CH(Ph)2 and -O2CCH(Ph)-Ph bonds slows, which results in the formation of different conformers. The energies of the retarded intermolecular exchange and of the retarded rotation of the phenyl radicals were calculated from 1H NMR and molecular mechanics data.
SYNTHESIS AND STUDY OF HETEROMETALLIC CO–BI COMPOUNDS BASED ON ETHYLENEDIAMINETETRAACETIC ACID. CRYSTAL AND MOLECULAR STRUCTURES OF [CO(DH)2(O -NH2C6H4CH3)2]2[BI2(M-EDTA)2(H2O)2] • 10H2O (DH2 IS DIMETHYLGLYOXIME)
(2002) Stăvilă, Vitalie; Gulea, Aurelian; Șova, Sergiu; Gdanec, M.; Simonov, Iurie
Compounds of the [Co(DH)2A2](BiEdta)·6H 2O type (where DH is the monodeprotonated dimethylglyoxime -ON=C(CH3)-(CH3)C=NOH; A is the o-, m-, or p-toluidine; and Edta is the ethylenediaminetetraacetate(4-) ion) were synthesized and studied. The composition and structures of the complexes were determined from their UV and 1H NMR spectra and from X-ray diffraction data. The isomer [Co(DH)2(o-NH2C 6H4CH3)2]2[Bi 2(μ-Edta)2(H2O)2]·10H 2O was structurally characterized using X-ray diffraction analysis. The crystals are triclinic: a = 12.153(2) Å, b = 12.824(3) Å, c = 16.215(3) Å, α = 67.73(3)°, β = 86.18(3)°, γ = 66.96(3)°, space group P1̄ , ρ(calcd) = 1.719 g/cm3, Z = 4. The structure is composed of complex binuclear [Bi2(μ-Edta) 2(H2O)2]2- anions, [Co(DH) 2(o-NH2C6H4CH3) 2]+ cations, and molecules of crystallization water. The Edta4- anion chelates with the Bi atom in a hexadentate manner (N2O4); the fifth O atom functions as a bridging ligand. The bismuth coordination polyhedron can be regarded as a strongly distorted antiprism. In the octahedral cation, the Co(III) atom coordinates four N atoms of two DH ligands (average Co-N 1.897 Å) and two N atoms of two o-toluidine molecules (Co-N 2.023 Å). Thermolysis of the complexes studied was found to proceed in several successive steps, namely, the deaquation, deamination, and pyrolysis of the ligands.
USE OF SOME CATALYSTS IN RADIOLYTICAL SPLIT OF WATER
(2002) Cecal, Alexandru; Paraschivescu, Andrei; Gulea, Aurelian; Palamaru, Mircea; Iordan, Alexandra; Popa, Karin; Craus, Mihai
The present paper deals with the study of catalyzed water radiolysis under the influence of γ-rays emitted by a 60Co source (Λ = 3 × 104 Ci) with a dose rate of 8.3 kGy/h, for hydrogen production. Thirty-one solid inorganic compounds, insoluble in water, were tested as catalysts. They belong to: coordination compounds of some metallic ions with organic ligands based on salycilaldehyde or naphthalenaldehyde derivatives, mixed oxides, RhCl3 supported on a Al2O 3 layer and bimetallic compounds with EDTA ligand. The released hydrogen quantity, determined by mass spectrometry, was approximately 7-35 times greater than the one produced by simple radiolysis of water, in the absence of catalysts.
COORDINATION COMPOUNDS OF COBALT, NICKEL, AND COPPER WITH ISONITROSOACETONE BENZOYLHYDRAZONE
(2002) Țapcov, Victor
Benzoylhydrazine and isonitrosoacetone react in ethanol with cobalt, nickel, and copper halides and acetates to give the coordination compounds MX2(HL)·nH2O, MX2(HL) 2·nH2O, and ML2·nH2O [M = Co, Ni, Cu; X = Cl, Br; HL = C6H5C(O)NHNC(CH 3)CHNOH; n = 1-4]. The same reactions performed in the presence of sodium acetate and pyridine (pH 7-8) yield the complexes MLCl·nH 2O and MPy2LCl·nH2O (n = 1-4). All the complexes have a pseudooctahedral coordination geometry. The hydrazone HL behaves as a tridentate O,N,N-donor ligand. Thermolysis of the substances involves dehydration (70-90°C), deaquation (155-170°C) or deamination (175-195°C), and complete thermal decomposition (285-360°C).
COORDINATION COMPOUNDS OF COPPER(II) WITH BENZOYLHYDRAZONES OF SUBSTITUTED SALICYLALDEHYDES
(2003) Samusi, Nina; Țapcov, Victor; Kerner, A.
Benzoylhydrazones of 5-nitro- (H2L1), 3-nitro- (H2L2), 5-chloro- (H2L3), 5-bromo- (H2L4), and 3,5-dibromosalicylaldehydes (H 2L5) react in ethanol with copper acetate to form complexes CuL1-5. In the presence of amines (A = C5H 5N, 3-CH3C5H4N), the above reactions give complexes CuL1-5A·nH2O (n = 0, 1). When cuprous bromide or nitrate and benzoylhydrazone H2L3 were used as starting materials, complexes Cu(HL3)X (X = Br-, NO3-) were isolated. The resulting complexes all are polynuclear structures in which azomethines H2L1-5 behave as tridentate O,N,O-ligands. Thermolysis of the complexes involves the stages of dehydration (70-90°C), deaquation (120-150°C) or deamination (150-180°C), and complete thermal decomposition (350-500°C).
LANTHANIDE COMPLEXES WITH N , N '-BIS(2- HYDROXYBENZYLIDENE)-2-HYDROXYPHENYLMETHANEDIAMINE
(2004) Samusi, Nina; Strelcov, Eugeniu; Țapcov, Victor; Gulea, Aurelian
Complexes of lanthanides with N,N′-bis(2-hydroxybenzylidene)-2- hydroxyphenylmethanediamine (H3L) were synthesized and investigated by the elemental, IR, magnetochemical, and thermogravimetric methods. Using the data obtained, they were found to have compositions Ln2L 2·nH2O and La2L2· MCl2·4H2O (Ln = La3+, Pr3+, Nd3+, Dy3+, Er3+; M = Cu2+, Co 2+, Ni2+; n = 4, 6). Suggestions on their structures were made. In the interval of 20-140°C, these complexes were shown to be high-resistance semiconductors.
SYNTHESIS, STRUCTURE AND PROPERTIES OF SOME 3D-ELEMENT COMPLEXES WITH 2-[2-(HYDROXYBENZYLIDENE)-AMINO]-2-HYDOXYMETHYLPROPANE-1,3-DIOL
(2004) Țapcov, Victor; Ciumacov, Iurie; Antoșciac, Boris; Bocelli, Gabrielle; Samusi, Nina; Gulea, Aurelian
2-[2-(Hydroxybenzylidene)-amino]-2-hydoxymethylpropane-1,3-diol (HL) reacts with cobalt, nickel, copper and zinc chlorides, bromides and acetates in water-ethanol solutions and gives MLX·nH2O and ML 2·nH2O complexes (M = Co, Ni, Cu, Zn; X = Cl, Br; n = 0-5). Single crystals of CuLBr were grown, and its crystal structure was determined by X-ray diffraction analysis. The crystals are tetragonal, a = 17.024(2), c = 8.720(2) Å, space group P421c, Z = 8, R 1 = 0.0349. In the structure of this complex, the copper atom coordinates the deprotonated HL molecule. The coordination polyhedron of the central atom is an elongated tetragonal pyramid. Its base is built of the imine nitrogen atom, phenolic and alcoholic oxygen atoms, and bromine atom. The apex of the pyramid is occupied by the bromine atom of the adjacent complex connected with the initial complex by the plane of sliding reflection. Thus, the crystal contains infinite chains of complexes running along the c axis, the complexes being united by both bridging bromine atoms and O-H⋯O hydrogen bonds. The conclusions on the compositions and structures of the remaining compounds were made on the basis of elemental and combined thermal analyses, IR spectroscopy, and magnetic chemistry data. The copper halide complexes were found to have dimeric, and the other metal complexes monomeric, structures. In the synthesized complexes, the azomethine HL can function as a bidentate or tridentate ligand. The thermolysis of the coordination compounds proceeds through the stages of elimination of crystal water molecules (75-90°C) or inner-sphere water molecules (145-155°C) and complete thermal destruction (485-550°C).
COORDINATION COMPOUNDS OF COPPER(II), NICKEL(II), AND COBALT(II) WITH β-THIOSEMICARBAZONES OF ISATIN AND N-METHYLISATIN
(2004) Samusi, Nina; Țapcov, Victor; Gulea, Aurelian
Isatin thiosemicarbazone (HL) reacts in aquoeus-ethanolic medium with copper(II) chloride and bromide (pH 7-7.5, ethanolic KOH) to give coordination compounds CuLX·nH2O (X = Cl, Br; n = 3, 4). In the presence of amines (A = C5H5N, 3-CH3C5H 4N, and 4-CH3C5H4N), complexes CuALX·2H2O and CuA2LX·H2O (X = Cl, Br) are formed. With nickel(II) or cobalt(II) chlorides, thiosemicarbazone HL, and pyridine (1:1:3) as starting compounds, compounds MPy 2LCl·H2O (M = Ni, Co) are isolated. Under similar conditions, N-methylisatin β-thiosemicarbazone (HL') reacts with chlorides of the above-noted metals in the presence of pyridine to give complexes MPy 2L'Cl·H2O (M = Cu, Ni, Co). All the complexes are monomeric and have a pseudooctahedral structure of the coordination unit. Thiosemicarbazones HL and HL1 in these complexes behave as tridentate monodeprotonated O,N,S-ligands. Thermolysis of these substances passes through the stages of dehydration (60-90°C), deaquation (135-140°C) or deamination (160-215°C), and complete thermal decomposition (560-670°C).
CRYSTAL STRUCTURE OF MONOPROTONATED NI(II) NITRILOTRIACETATE TETRAHYDRATE
(2004) Petrenko, Peter A.; Gdaniec, Maria; Simonov, Iurie; Stăvilă, Vitalie; Gulea, Aurelian
A Ni(II) complex of the composition Ni(HNta)·4H 2O (I) was synthesized. Its structure was found to consist of neutral mononuclear [Ni(HNta)(H 2O) 3] complexes and crystallization water molecules. The Ni atom has octahedral surrounding and is coordinated to tridentate-chelate HNta 2- ligand through the N atom and O atoms of two deprotonated acetate groups and through the O atoms of three water molecules. The structure of I was compared with those of the Zn(HNta)·4H 2O and Co(HNta)·4H 2O complexes isostructural to I. Thermogravimetric method showed that the decomposition of compound I occurs through several successive stages of dehydration, deaquation, decarboxylation, and the formation of inorganic residue.
SYNTHESIS AND STRUCTURE OF DI(M-OPHENOXY )-BIS{NITRATO-2-[2- (HYDROXYETHYLIMINO)-METHYL]-PHENOLOIMIDAZOLECOPPER}
(2004) Ciumacov, Iurie; Antoșciac, Boris; Țapcov, Victor; Bocelli, Gabrielle; Gulea, Aurelian
The crystal structure of di(μ-O phenoxy)-bisnitrato-2-[2- (hydroxyethylimino)-methyl]-phenoloimid-azolecopper was determined. The crystals are monoclinic: a = 10.222(2) , b = 13.810(3) , c = 10.620(2) , β =103.67(3)°, space group P2 1/n, Z = 2, R = 0.050. The copper atom coordinates the singly deprotonated 2-[2-(hydroxyethylimino)-methyl]-phenol molecule, imidazole, and nitrate ion. The coordination polyhedron of the central atom is an extended tetragonal bipyramid with imine and imidazole nitrogen atoms and phenol and alcohol oxygen atoms lying in its base. One axial vertex of the bipyramid is occupied by the oxygen atom of the nitrato group and the other vertex, by phenol oxygen atom of the neighboring complex joined with the initial complex by the symmetry center. Two bridging phenol oxygen atoms unite the complexes into a centrosymmetrical dimer.
COORDINATION COMPOUNDS OF COPPER(II) NITRATE WITH PRODUCTS OF AMINOTRIS(HYDROXYMETHYL)METHANE CONDENSATION WITH SALICYL- AND 5-NITROSALICYLALDEHYDES: SYNTHESIS AND CRYSTAL STRUCTURES
(2005) Ciumacov, Iurie; Țapcov, Victor; Simonov, Iurie; Antoșciac, Boris; Bocelli, Gabrielle; Perrin, Monique; Starnicova, Zoia; Samusi, Nina; Gulea, Aurelian
The crystal structures of copper(II) nitrate complexes with 2-(2-hydroxybenzylideneamino)-2-hydroxymethylpropane-1,3-diol (HL) and 2-hydroxymethyl-2-(2-hydroxy-5-nitrobenzylideneamino)propane-1,3-diol (HL 1) were determined. The resulting complexes were formulated as [Cu3OL3(H2O2]NO3 • 3H2O (I) and [Cu(H2O)L1]NO3 (II). The crystals of I are monoclinic, a = 17.809(4) Å, b = 30.549(6) Å, c = 18.962(4) Å, β = 115.36(3)°, space group Cc, Z = 8, R = 0.0482. Complex I is composed of two independent three-dimensional μ 3-oxo complexes; the coordination polyhedron of the copper atoms in both compounds is an elongated tetragonal bipyramid. The coordination polyhedron of the third Cu atom is a tetragonal pyramid. The bases of the pyramids are composed of the oxygen atoms of the phenol and alcohol OH groups, the imine N atom of ligand L, and μ 3-oxo atoms. The phenol and water O atoms serve as the apices in both the tetragonal bipyramids. The crystals of II are triclinic, a = 6.062(1) Å, b = 7.701(2) Å, c = 16.162(3) ̊, α = 88.15(3)°, β = 84.94(3)°, γ = 78.13(3)°, space group P1̄, Z = 2, R = 0.0272. Complex II is composed of polymer chains formed by coordination bonds between the copper atom and two O atoms of the amino alcohol in the azomethine of the neighboring complex connected to the initial one by translation along the x axis. These chains are linked through hydrogen bonds involving the oxygen atoms of the NO2 groups. The benzene rings of the azomethine ligands of the adjoining complexes from different chains are antiparallel to each other. The coordination polyhedron of the central atom is an elongated tetragonal bipyramid. Its equatorial plane is formed by the phenol O atom, one of the alcohol O atoms, the N atom of ligand L1, and the O atom of the amino alcohol in the neighboring complex. The apices are the O atom of the water molecule and the O atom of the amino alcohol in the neighboring azomethine molecule. In complexes I and II, the outer-sphere nitrato group mainly serves to unite trimers and polymers in the crystal by means of hydrogen bonds.
PROCESSES OF RADICAL AUTO-PURIFICATION OF AQUATIC SYSTEMS
(Tipografia Academiei de Ştiinţe a Moldovei, 2005) Boldescu, Veaceslav; Gladchi, Viorica
THE INFLUENCE OF BENZOIC ACID ON THE RADICAL SELFPURIFICATION PROCESSES IN NATURAL MEDIUM
(Tipografia Academiei de Ştiinţe a Moldovei, 2005) Gladchi, Viorica; Goreaceva, Nelly; Rusu, Nicoleta
SYNTHESIS AND ANTIMICROBIAL ACTIVITY OF COORDINATION COMPOUNDS OF COPPER WITH SUBSTITUTED SALICYLALDEHYDE THIOSEMICARBAZONES
(Springer, 2005) Prisakar, V. I.; Tsapkov, V. I.; Buracheeva, S.A.; Byrke, M.S.; Gulya, A. P.
New coordination compounds of copper(II) with thiosemicarbazones of 5-chloro-, 5-bromo-, 5-nitro-, 5-methyl-, 3,5-dichloro-, and 3,5-dibromo-substituted salicylaldehyde have been synthesized and tested with respect to eight strains of staphyloccoccus, streptococcus, and colon bacillus. These compounds exhibit high antimicrobial activity. The composition and structure of the synthesized complexes have been studied by means of elemental analysis and by magnetochemical, IR, and thermogravimetric techniques. The antimicrobial activity of the obtained coordination compounds depends both on the nature of substituents in the benzene ring of salicylaldehyde and on the nature of acid ligands. The maximum antimicrobial activity was observed for copper(II) complexes with thiosemicarbazone of 3,5-dibromsalicyladehyde.
PĂTRUNDEREA ŞI TRANSFORMĂRILE CHIMICE ALE SUBSTANŢELOR ANTIBACTERIENE ÎN MEDIUL ÎNCONJURĂTOR
(2005) Boldescu, Veaceslav; Gladchi, Viorica
Summary: Recently, pharmaceuticals and personal care products (PPCPs) with their metabolites have been detected as common contaminants in surface waters throughout the world. The most frequently detected compounds were hormones, antibiotics, analgesics, fragrances, disinfectants, diagnostic agents, sunscreen agents, tranquilizers. The major possible impact of antibiotics and other antibacterial products is development of resistant bacteria and potential to disturb environmental bacterial community and processes. One of the main physico-chemical processes of PPCPs degradation is considered photolysis. This work is dedicated to the photodegradation of the antibiotic oxytetracycline hydrochloride. The study has been performed with and without addition of the copper (II) ions which are main catalysts in natural redox processes. It has been found that the photodegradation rate of oxytetracycline hydrochloride for the model system with addition of Cu2+ is lower than for the system without addition of Cu2+. Moreover, there exists a qualitative difference between transformational products formed with and without addition of Cu2+. It is obvious that the formation of Cu-antibiotic complexes causes these differences in the rates and products. Obtained results emphasize the importance of identifying the transformation products and the degradation rates of PPCPs in the presence of natural transition ions (Cu2+, Fe3+, Mn4+) and other cations (Ca2+, Mg2+), which can form complexes with PPCPs, in order to obtain results closer to the real environmental conditions.
PĂTRUNDEREA ŞI TRANSFORMĂRILE CHIMICE ALE SUBSTANŢELOR ANTIBACTERIENE ÎN MEDIUL ÎNCONJURĂTOR
(2005) Boldescu, Veaceslav; Gladchi, Viorica
Recently, pharmaceuticals and personal care products (PPCPs) with their metabolites have been detected as common contaminants in surface waters throughout the world. The most frequently detected compounds were hormones, antibiotics, analgesics, fragrances, disinfectants, diagnostic agents, sunscreen agents, tranquilizers. The major possible impact of antibiotics and other antibacterial products is development of resistant bacteria and potential to disturb environmental bacterial community and processes. One of the main physico-chemical processes of PPCPs degradation is considered photolysis. This work is dedicated to the photodegradation of the antibiotic oxytetracycline hydrochloride. The study has been performed with and without addition of the copper (II) ions which are main catalysts in natural redox processes. It has been found that the photodegradation rate of oxytetracycline hydrochloride for the model system with addition of Cu2+ is lower than for the system without addition of Cu2+. Moreover, there exists a qualitative difference between transformational products formed with and without addition of Cu2+. It is obvious that the formation of Cu-antibiotic complexes causes these differences in the rates and products. Obtained results emphasize the importance of identifying the transformation products and the degradation rates of PPCPs in the presence of natural transition ions(Cu2+, Fe3+, Mn4+) and other cations (Ca2+, Mg2+), which can form complexes with PPCPs, in order to obtain results closer to the real environmental conditions.
SYNTHESIS AND STRUCTURE OF HETEROMETALLIC CHROMIUM(III) COMPLEXES WITH ETHYLENEDIAMINETETRAACETIC ACID
(2005) Ciornea, Victor; Filippova, Irina; Gulea, Aurelian; Șova, Sergiu; Borta, A.; Simonov, Iurie
The complexes [M(Tsc)2][Cr(Edta)]2, where M is Ni, Cu; Tsc is thiosemicarbazide; Edta4- is the ethylenediaminetetraacetate anion, were synthesized and characterized by X-ray diffraction. The ionic structures are composed of the [M(Tsc)2] 2+ cations and [Cr(Edta)]- anions with a component ratio of 1 : 2. The cation has a distorted trans-square coordination. The carboxyl groups of the H4Edta molecule are deprotonated and the ligand is attached to the Cr atom in the hexadentate chelating mode. The cations and anions are linked by a system of hydrogen bonds.
THE INFLUENCE OF SOME ORGANIC ACIDS ON THE RADICAL SELF-PURIFICATION PROCESS OF THE AQUATIC MEDIUM
(Academia de Ştiinţe a Moldovei, 2005) Bunduchi, Elena; Gladchi, Viorica