Browsing by Author "Stavila, Vitalie"

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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.
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.
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.