Browsing by Author "Bulimestru, Ion"

Filter results by typing the first few letters
Now showing 1 - 20 of 20
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    ANTIMICROBIAL AND ANTIFUNGAL ACTIVITY OF CU(II) AND BI(III) COMPLEXES BASED ON AMINOPOLYCARBOXYLATE IONS AND 2-FORMYL AND 2-ACETYLPYRIDINE THIO- SEMICARBAZONES
    (2021) Neguța, Elena; Balan, Greta; Gulea, Aurelian; Bulimestru, Ion
    The biological properties of thiosemicarbazones are often related to metal coordination, which as result affects lipophilicity that controls the rate of entry into the cell. Metal complexes are generally more active than the free ligand, or the metal complex can be a vehicle for activation of the ligand as the cytotoxic agent. Among biologically ac- tive metal compounds, copper (II) complexes with 2-formyl and 2-acetylpyridine thio- semicarbazones proved to be among the most potent antiviral, antitumor and anti-inflam- matory agents. Bismuth compounds have been widely used in medicine for more than two centuries due to their high effectiveness and low toxicity. In the antimicrobial realm, ap- plications have been widespread, due to bismuth antiseptic, astringent, protective, ant- acid, antisecretory and local gastrointestinal properties.
  • Thumbnail Image
    Item
    CHIMIE GENERALĂ ŞI ANORGANICĂ: INDICAȚII METODICE PENTRU REALIZAREA LUCRĂRILOR DE LABORATOR
    (CEP USM, 2022) Cotovaia, Aliona; Popa, Nelea; Bulimestru, Ion
    Obiectivele acestor cursuri cuprind însuşirea noţiunilor și legităților de bază ale chimiei, formarea de abilităţi şi deprinderi practice pentru desfăşurarea experimentelor chimice și interpretarea rezultatelor, formarea şi dezvoltarea gândirii ştiințifice la studenţi. Un rol esențial în realizarea acestor obiective revine lucrărilor practice și de laborator, în cadrul cărora, prin conţinut şi abordare, se urmăreşte formarea aptitudinilor pentru activitatea experimentală şi de cercetare, îmbogăţirea deprinderilor de utilizare a ustensilelor de laborator, definirea, descrierea şi interpretarea principiilor, modelelor şi metodelor ştiinţifice pentru desfăşurarea optimă a etapelor în cadrul procedurilor experimentale.
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    COMPLECȘI Ln( III) - Bi(III) ÎN BAZA IONILOR TRIETILENTETRAAMINHEXAACETAT - PRECURSORI MOLECULARI PENTRU OXIZII MICȘTI BiLnO 3
    (CEP USM, 2020) Popa, Nelea; Bulimestru, Ion; Gulea, Aurelian
    Lucrarea este axată pe sinteza și studiul unui șir de combinații coordinative heterometalice ale lantanidelor(III ) și bis mutului(III) cu formula generală LnBi(ttha)·nH 2 O (ttha 6 - = trietilentetraaminhexaacetat) pe rol de precursori moleculari pentru obținerea oxizilor micști BiLnO 3 . În baza spectrelor IR a fost stabilită prezența a două serii de complecși analogi (Ln (III) = La, Pr, Nd, Gd, Dy, unde n=7 și Ln(III) = Ho, Er, unde n= 10) . Analiza termogravimetrică efectuată în flux de oxigen generează oxidul preconizat BiLnO 3 deja la 600 o C, pe când în flux de azot acest proces nu este finalizat nici la 900 o C. Difracția ra zelor X pe pulberile obținute la descompunerea termică a precursorilor a confirmat că viteza de cal - cinare și natura ionilor Ln(III) nu influențează compoziția reziduurilor finale, în toate cazurile obținându - se oxizii heterometalici preconizați BiLnO 3 în stare pură.
  • Thumbnail Image
    Item
    COMPUŞI COORDINATIVI DE TIP CU(II) – BI(III) CU DERIVATI AI 4-ALILTIOSEMICARBAZONELOR UNOR ALDEHIDE
    (CEP USM, 2018) Popa, Nelea; Graur, Vasile; Bulimestru, Ion
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    CRYSTAL STRUCTURE OF [Co(thios) 3 ] 2 [Bidtpa] 2 (NCS)(OH)⋅8H2O
    (Academia de Ştiinţe a Moldovei, 2006) Petrenko, Peter A.; Bulimestru, Ion; Simonov, Yurii A.; Gdaniec, Maria; Gulea, Aurelian
    Bismuth-based mixed-oxides have been studied extensively for a number of potentially useful physical properties like oxygen ion conductivity, ferroelectricity, superconductivity and catalysts in different oxidation processes. The use of bismuth complexes as precursors for new heterometallic oxide systems turned out to be a more effective route compared to traditional ceramic synthesis. Thus, controlled pyrolysis of alkoxide, carboxylate or polyaminopolycarboxylate precursors has frequently been used to synthesize highly dispersed bismuth containing mixed-oxides and solid solutions. Diethylenetriaminepentaacetic acid (H5Dtpa) gives numerous stable complexes with d, f, and p elements, including Bi. Most frequently, complexes with H5Dtpa are more stable than those with its analogues. Recently, we have characterized two heterometallic coordination compounds, [Co(thios)3]2[Bi(Dtpa)]2SO4·6H2O (I) and [Co(thios)3]4[BiDtpa]4⋅(SO4)2⋅20H2O (II) containing complex cations and anions (thios=thiosemicarbazide). In this work we present synthesis and crystal structure of a new heterometallic compound [Co(thios)3]2[BiDtpa]2⋅(NCS)(OH)⋅8H2O (III) (see fig.). The crystal structure of III is built of complex cations [Co(thios)3]3+, three types of anions [Bi(Dtpa)]2-, [NCS]2-, (OH)- and water molecules. The Bi atom coordination polyhedron is a nanohedron and its coordination number is nine. The coordination of Dtpa residues to the bismuth atom gives rise to five glycine and two ethylenediamine metallocycles which are essentially non-planar. The complex cation [Co(thios)3]3+ is a typical Co(III) tristhiosemicarbazide fac-isomer.
  • Thumbnail Image
    Item
    CRYSTAL STRUCTURES OF NEW POLYNUCLEAR COPPER(II) TRIETHANOLAMINE - SALICYLATE COMPLEXES
    (Academia de Ştiinţe a Moldovei, 2006) Bulimestru, Ion; Whitmire, Kenton; Stavila, Vitalie; Gulea, Aurelian
    Copper species are widely found in nature and are present in many enzymes as polynuclear centers that catalyze selectively various oxidation reactions. Although increasing attention has been paid to the design of Cu complexes as models of copper oxidases, the use of multicopper complexes for such reactions still remains an unexplored area of research. The main goal of this work was to find a simple synthetic route to generate multinuclear copper complexes as potential catalysts in different oxidation processes. As a result of the performed investigations, two new polynuclear copper compounds with triethanolamine (H3tea) and salicylic (H2sal) or 3,5-ditertbutylsalicylic (3,5-C4H9-H2sal) acids as ligands have been synthesized and their composition and crystal structure determined (see fig.).figureFig. ORTEP representation of [Cu2(3,5-C4H9-Hsal)2(H2tea)2] I (a) and [Cu5(Htea)3(Hsal)2(sal)] II (b) with hydrogen atoms omitted for clarity. Compound I has a similar structure with the previously described [Cu2(C6H5COO)2(H2tea)2] [1] and can be viewed as a dimer of two neutral {Cu(3,5-C4H9-HSal)(H2tea)} units. The dimerization is achieved through the bridging of one oxygen atom of each Htea2- unit. The carboxylate groups are bound in a terminal fashion to each copper atom. In complex II five Cu2+ ions are connected by means of bridging oxygen atoms of hydroxyl and carboxyl groups of salicylic moieties and as well of hydroxyl oxygen atoms of three Htea2- ligands in a non-equivalent mode.
  • Thumbnail Image
    Item
    HETEROMETALLIC LANTHANIDE(III)-BISMUTH(III) POLYAMINOPOLYCARBOXYLATE COMPLEXES: SYNTHESIS AND CRYSTAL STRUCTURE
    (Academia de Ştiinţe a Moldovei, 2012) Bulimestru, Ion; Popa, Nelea; Shova, Sergiu; Gulea, Aurelian
  • Thumbnail Image
    Item
    IN VITRO ANTILEUKEMIA ACTIVITY (HL-60 CELLS), OF SOME 3d METAL COMPLEXES. CHEMICAL SYNTHESIS AND STRUCTURE – ACTIVITY RELATIONSHIP
    (Academia de Ştiinţe a Moldovei, 2006) Gulea, Aurelian; Poirier, Donald; Roy, Jenny; Stavila, Vitalie; Bulimestru, Ion; Tsapkov, Victor; Bîrcă, Maria; Popovschi, Lilia
    28 years after the first approval of cisplatin in the clinic against a number of cancer diseases, cisplatin and related compounds continue to be among the most efficient anticancer drugs used so far. Efforts are focused to develop novel platinum- and non-platinum-based antitumor drugs to improve clinical effectiveness, to reduce general toxicity and to broaden the spectrum of activity. Thiosemicarbazones and their transition metal complexes demonstrated potent cytotoxic activity against a series of murine and human suspended cultured tumor cells. The aim of our communication is to report the synthesis of novel 3d metal complexes with some di- and tri-dentate ligands containing N, O and S donor atoms which have different electronic and geometrical structure confirmed by elemental and thermal analyses, molar conductance, magnetic measurements, IR and NMR data. In order to investigate the antileukemia activity 27 metal complexes were tested as inhibitors of HL60 cells growing. It was established that the nature, electronic structure and coordination number of the central atom, the geometric configuration of metal complexes and the nature of the ligands (donor atoms) are important in biological activity prediction. In investigated series of complexes the most active are those having a copper (II) or a cobalt (II) species. For the octahedral environment of the cobalt complexes the electronic configuration is important Co2+ ( 3d7 ) > Co3+ ( 3d6 ). This different activity can be explained by the fact that in solutions Co2+ complexes with inner coordination sphere lifetime of the ligands 10-4 - 10-5 s are more labile in comparison with the inert Co3+ complexes (lifetime 103 – 105 s). Copper (II) complexes with different type of electronic hybridisation and geometric structure produce also different activity. We find that a square planar Cu2+ complexes have essential activity. The activity of such square planar complexes is influenced also by the nature of the ligand donor atoms. In fact complexes with coordinated ligands containing N, O and S chelate donor atoms are essentially more active than complexes including inner sphere only nitrogen or oxygen. In this case the presence of coordinated ligand containing sulphur donor atom is indicated. If sulphur ligand donor atom is blocked by CH3 group the biological activity became unsignificant.
  • Thumbnail Image
    Item
    IN VITRO ANTILEUKEMIA, ANTIBACTERIAL AND ANTIFUNGAL ACTIVITIES OF SOME 3D METAL COMPLEXES: CHEMICAL SYNTHESIS AND STRUCTURE – ACTIVITY RELATIONSHIPS
    (Taylor & Francis Open, 2008) Gulea, Aurelian; Poirier, Donald; Roy, Jenny; Stavila, Vitalie; Bulimestru, Ion; Tapcov, Victor; Birca, Maria; Popovschi, Lilia
    The present paper describes the synthesis, characterization and in vitro biological evaluation screening of different classes (ammoniacates, dioximates, carboxylates, semi- and thiosemicarbazidates) of Co(II), Co(III), Cu(II), Ni(II), Mn(II), Zn(II) and Fe(III) complexes. Schiff bases were obtained from the reaction of some salicyl aldehydes with, respectively, furoylhydrazine, benzoylhydrazine, semicarbazide, thiosemicarbazide and S-methylthiosemicarbazide to give tridentate ligands containing ONO, ONS or ONN as donor atoms. The synthetic metal complexes are of various geometrical and electronic structures, thermodynamic and thermal stabilities, and magnetic and conductance properties. All complexes, except those of Cu, are octahedral. Some Cu, Co and Mn compounds have a dimeric or a polymeric structure. The composition and structure of complexes were analysed by elemental analysis, IR and 1 H NMR and 13C NMR spectroscopies, and magnetochemical, thermoanalytical and molar conductance measurements. All ligands and metal complexes were tested as inhibitors of human leukemia (HL-60) cells growth, and the most potent, the Cu(II) complexes, have been also tested for their in vitro antibacterial and antifungal activities. Structure-activity relationships were carried out.
  • Thumbnail Image
    Item
    INFLUENCE OF TYPE OF PRECURSORS ON THE SOL-GEL SYNTHESIS OF THE LACOO3 NANOPARTICLES
    (De Gruyter Open, 2014) Cornei, Nicoleta; Feraru, Simona; Bulimestru, Ion; Sandu, Andrei Victor; Mita, Carmen
    Perovskite-type LaCoO3 was prepared by sol-gel method using nitrates / chlorides as precursors and citric acid as chelating agent. Chemical composition was obtained by means of EDX method. The structures of sintered samples were investigated by scanning electron microscopy (SEM), IR and XRD analysis. The results of X-ray diffraction indicated that the LaCoO3nanopowders obtained using nitrate as precursors had a rhombohedral perovskite-type crystal structure (S. G: R-3c), while that obtained using chloride as precursors had a mixture of LaCoO3, LaOCl and Co3O4. The all lanthanum cobaltites exhibit catalytic activity on the decomposition of hydrogen peroxide, ascribed to their higher surface and Co3+
  • Thumbnail Image
    Item
    MAGNETIC STUDY IN SOLUTION OF LANTHANIDE(III)-BISMUTH(III) COORDINATION COMPOUNDS BY MEANS OF NMR SPECTROSCOPY
    (Academia de Ştiinţe a Moldovei, 2012) Gulea, Aurelian; Popa, Nelea; Barba, Alic; Bulimestru, Ion
  • Thumbnail Image
    Item
    MOLECULAR PRECURSORS BASED ON HETEROMETALLIC BISMUTH(III)-VO(II) OR -Cu(II) COORDINATION COMPOUNDS
    (Academia de Ştiinţe a Moldovei, 2012) Bulimestru, Ion; Roussel, Pascal; Capet, Frederic; Vannier, Rose-Noelle; Wignacourt, Jean-Pierre; Gulea, Aurelian
  • Thumbnail Image
    Item
    NEW HETEROPOLYNUCLEAR BI-SM AND BI-HO COMPLEXES WITH ETHYLENEDIAMINETETRAACETIC ACID
    (Academia de Ştiinţe a Moldovei, 2006) Popa, Nelea; Roussel, Pascal; Wignacourt, Jean-Pierre; Bulimestru, Ion; Gulea, Aurelian
    The search for bismuth-lanthanide coordination compounds that could be used as molecular precursors for Bi-Ln-based oxide-type materials displays a wide interest in the relationship with the numerous applications of such inorganic materials as ion conductors (Bi-La, Nd, Sm), ferroelectrics (Bi-Sm, La) or inorganic pigments (Bi-Ho) [1]. When compared with the traditional ceramic route involving oxides of the component metals, these precursor methods actually provide materials displaying a higher homogenity and specific surface area. As an ongoing effort to synthesise new potential precursors for inorganic materials, we have obtained two new heterometallic coordination compounds with ethylenediamine tetraacetate ion as a ligand with the following general formulae: LnBiEdta(NCS)2⋅4H2O (Ln = Sm, Ho). The composition has been confirmed by elemental analysis, TG/TGA study, IR spectroscopy and single crystal X-ray diffraction. The results of X-ray study revealed that the compounds are isomorphous, crystallizing in P21/n space group with the average cell parameters: a = 9.3, b =16.7, c = 14.5 (Å), β=103º. The crystal structure represents a 3D coordination network (see fig.) sustained by the four bridging carboxylate groups of the Edta4- ligand and one of the two NCS- ligands coordinated to Bi through S atom and to Ln through N atom. The second NCS-group is coordinated to Bi ion as a monodentate ligand. Analogous tridimensional structures have been obtained with nitrate ion [2].figureFig. 1. Packing of LnBiEdta(NCS)2⋅4H2O.
  • Thumbnail Image
    Item
    PREPARATION OF MIXED-OXIDE MATERIALS FROM HETEROMETALLIC COORDINATION COMPOUNDS
    (Academia de Ştiinţe a Moldovei, 2015) Bulimestru, Ion; Mentre, Olivier; Tancret, Nathalie; Cornei, Nicoleta; Shova, Sergiu; Popa, Nelea; Gulea, Aurelian
  • Thumbnail Image
    Item
    SINTEZA ȘI STUDIUL COMPUȘILOR COORDINATIVI AI Cu(II) ȘI Bi(III) CU IONI AMINOPOLICARBOXILAT ȘI TIOSEMICARBAZONE ALE 2-FORMILPIRIDINEI ȘI DERIVAȚILOR EI
    (2024) Neguța, Elena; Bulimestru, Ion
    Scopul lucrării: studiul comparativ structural și biologic al complecșilor homo- și heterometalici ai Cu(II) și Bi(III) cu liganzi micști: aminopolicarboxilat (APC) - tiosemicarbazone ale 2-formilpiridinei și derivaților ei pentru elucidarea factorilor care amplifică activitatea biologică.
  • Thumbnail Image
    Item
    SINTEZA ȘI STUDIUL COMPUȘILOR COORDINATIVI HOMO- ȘI HETEROMETALICI AI CU(II) ȘI BI(III) CU 4-ETILTIOSEMICARBAZONELE 2-FORMIL ȘI 2-ACETILPIRIDINEI
    (CEP USM, 2023) Neguța, Elena; Gulea, Aurelian; Cotovaia, Aliona; Bulimestru, Ion; Bălan, Greta; Șova, Sergiu
    În această lucrare sunt prezentate sinteza și studiul a două serii de compuși coordina- tivi homo- și heterometalici ai Cu(II) și Bi(III) cu 4-etiltiosemicarbazonele 2-formil și 2-acetilpiridinei, cu formulele generale: {Cu(HL)}Cu(edta)•nH2O, {Cu(L)}2Cu(edta)•nH2O în cazul complecșilor homometalici ai Cu(II) și {Cu(L)}Bi(edta)•nH2O (n = 1 - 5), pentru compușii heterometalici Cu(II)-Bi(III). În complecșii sintetizați, 4-etiltiosemicarbazonele 2-formilpiridinei (HFoPyTSC-4Et) și 2-acetilpiridinei (HAcPyTSC-4Et) sunt în formă monodeprotonată (L) sau nedeprotonată (HL), iar edta4- reprezintă ionul etilendiamintetracetat. A fost determinată activitatea antimicrobiană și antifungică a compușilor homo- și heterometalici obținuți. Rezultatele au demonstrat că cea mai mare activitate antimicrobiană a manifestat-o compusul [Cu(AcPyTSC-4Et)Bi(edta)]·5H2O, fiind de cca 76 și 19 ori mai activ decât Furacilina (CMI = 4,67 μg/mL) în cazul tulpinilor Staphylococcus aureus (ATCC 25923) și Bacillus cereus (ATCC 11778), respectiv. Iar împotriva tulpinei Candida albicans, cel mai activ agent antifungic a fost compusul {Cu(AcPyTSC-4Et)}2Cu(edta)·H2O, cu CMI = 0,98 μg/mL, care este de cca 32 de ori mai activ decât Nistatina (CMI = 32,0 μg/ mL).
  • Thumbnail Image
    Item
    SISTEME POLIMERICE DIN METALOFTALOCIANINĂ DE ZINC CU CHITOSAN PENTRU TERAPIA FOTODINAMICĂ
    (CEP USM, 2021) Bulimestru, Ion; Popa, Nelea; Tiuleanu, Pavel; Lungu, Ion; Potlog, Tamara; Robu, Ștefan