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  • Author or Editor: Carmen Chifiriuc x
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Abstract  

The investigations concerning the thermal behaviour of a series of Ni(II) and Cu(II) complexes of type [NiLCl2mH2O ((1) L:L1, m=6; (3) L:L2, m=4) or [CuLCl]nCln·mnH2O ((2) L:L1, m=6; (4) L:L2, m=4) are presented. The ligands L(1) and L(2) have been synthesised by template condensation of 3,6-diazaoctane-1,8-diamine or 1,2-diaminoethane with formaldehyde and 2-amino-4H-1,2,4-triazole. The bonding and stereochemistry of the complexes have been characterised by IR, electronic and magnetic studies at room temperature. The in vitro qualitative and quantitative antimicrobial activity assays showed that the complexes exhibited variable antimicrobial activity against planktonic as well as biofilm embedded Gram-negative, Gram-positive and fungal strains. The thermal behaviour provided confirmation of the complexes composition as well as the number and nature of water molecules and the intervals of thermal stability.

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Abstract  

Schiff bases obtained by the condensation of 2-amino-5-mercapto-1,3,4-thiadiazole with 2,4-pentandione or 1-phenyl-1,3-butandione were synthesized and characterized in order to obtain polydentate ligands HL1 and HL2, respectively. The complexes with these ligands of the type M(L)Cl·nH2O [(1) M:Ni, L:L1, n = 0.5; (3) M:Ni, L:L2, n = 0.5]; [(2) M:Cu, L:L1, n = 1; (4) M:Cu, L:L2, n = 0] were also synthesized and characterized. The modifications evidenced in IR spectra of complexes were correlated with the presence of monodeprotonate Schiff bases. The electronic spectra display the characteristic pattern of square-planar stereochemistry. The in vitro qualitative and quantitative antimicrobial activity assays showed that the new complexes exhibited variable antimicrobial activity. The thermal analyses have evidenced the thermal intervals of stability and also the thermodynamic effects that accompany them. Schiff bases and complexes have a similar thermal behaviour. Processes as water elimination, melting, chloride anion removal as well as oxidative degradation of the organic ligands were observed.

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Journal of Thermal Analysis and Calorimetry
Authors: Rodica Olar, Mihaela Badea, Dana Marinescu, Emilia Iorgulescu, Eliza Frunza, Veronica Lazar, and Carmen Chifiriuc

Abstract  

New complexes of type [Cu(HTBG)2]Cl2 (1), [Cu(TBG)2]·3H2O (2) and [CuL]·nH2O (3) L:L1, n = 2 and (4) L:L2, n = 1 (HTBG: 2-tolylbiguanide, L1 and L2: ligands resulted from 2-tolylbiguanide, ammonia/hydrazine and formaldehyde one pot condensation) were synthesised and characterised. The features of complexes have been assigned from microanalytical, IR and UV–Vis data. Redox behaviour was established by cyclic voltammetry. The in vitro qualitative and quantitative antimicrobial activity assays showed that the complexes exhibited variable antimicrobial activity against Gram-negative and Gram-positive strains isolated from the hospital environment. The thermal analyses have evidenced the thermal intervals of stability and also the thermodynamic effects that accompany them. After water elimination, complexes have a similar thermal behaviour. Processes as water elimination, melting, chloride anion removal as well as oxidative degradation of the organic ligands were observed. The final product of decomposition was copper (II) oxide.

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Journal of Thermal Analysis and Calorimetry
Authors: Mihaela Badea, Rodica Olar, Dana Marinescu, Veronica Lazar, Carmen Chifiriuc, and Gina Vasile

Abstract  

This paper reports the investigation on the thermal stability of new complexes with mixed ligands of the type [Cd(NN)(C3H3O2)2(H2O)m]·nH2O [(1) NN: 1,10-phenantroline, m = 1, n = 0; (2) NN: 2,2′-bipyridine, m = 0, n = 1.5 and (C3H3O2): acrylate anion]. The IR data indicate a bidentate coordination mode for both heterocyclic amine and acrylate. The in vitro qualitative and quantitative antimicrobial activity assays showed that the complexes exhibited variable antimicrobial activity against planktonic as well as biofilm embedded Gram-negative (Escherichia coli, Klebsiella sp., Proteus sp., Salmonella sp., Shigella sp., Acinetobacter boumani, Pseudomonas aeruginosa), Gram-positive (Bacillus subtilis, Staphylococcus aureus) and fungal (Candida albicans) strains, reference and isolated ones from the hospital environment. The thermal behaviour steps were investigated in synthetic air flow. The thermal transformations are complex processes according to TG and DTA curves including dehydration, amine as well as acrylate thermolysis. The final products of decomposition are the most stable metal oxides.

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Journal of Thermal Analysis and Calorimetry
Authors: Cristina Bucur, Mihaela Badea, Calu Larisa, Dana Marinescu, Maria Nicoleta Grecu, Nicolae Stanica, Mariana Carmen Chifiriuc, and Rodica Olar

Abstract

Novel complexes of type M2L(CH3COO)4·nH2O (M:Ni, n = 4; M:Cu, n = 2 and M:Zn, n = 0; L: ligand resulted in 1,2-phenylenediamine, 3,6-diazaoctane-1,8-diamine and formaldehyde template condensation) were synthesised and characterised. The features of complexes have been assigned from microanalytical, IR, UV–Vis, 1H NMR, EPR as well as magnetic data at room temperature. Processes as water elimination as well as oxidative degradation of both organic components (bismacrocycle and acetate) were observed. The final product of decomposition was metal (II) oxide as powder X-ray diffraction indicates.

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