A study of novel cobalt(II) octaazamacrocyclic complexes with aminocarboxylates or their derivativ

Four new air-stable mixed-ligand Co(II) complexes having the general formula [Co2(Y)tpmc]Z3×q(H2O/CH3CN) (HY = N-methylglycine/N,N-dimethylglycine, Z = BF4-, qH2O = 4 or 3; HY = S-norvaline/S-valine Z = ClO4- , qCH3CN = 0.5; qH2O = 0.5; tpmc = N,N’,N’’,N’’’-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane) were prepared. The composition, some physical and chemical properties and their tentative geometries were evaluated based on elemental analysis (C, H, N), conductometric and magnetic measurements, spectroscopic data (UV/Vis, IR) and cyclic voltammetry. The data were compared with earlier described analogous complexes containing the macrocyclic ligand and aliphatic aminocarboxylates. It is assumed that all complexes are binuclear with an exo coordination mode of the octaazamacrocyclic pendant ligand in the boat conformation. In addition, two –N–(CH2)2–N– portions of the cyclam ring within the tpmc ligand and Co(II) ions in the high-spin state are most probably bridged via oxygen atoms from the anion of the amino-carboxylate/derivatives, whereas nitrogen atoms rest uncoordinated. In all cases, a combined chelate-bridged coordination is proposed as the most probable. The complexes were electrochemically stable in the potential range –1.0 to 1.0 V. They were also preliminary assayed toward some microorganisms together with the ligands, starting simple salts and solvents as test substances. In some cases, certain antimicrobial activity of the complexes was detected

Binuclear biologically active Co(II) complexes with octazamacrocycle and aliphatic dicarboxylates

Four new cationic Co(II) complexes with N,N',N '',N'''-tetrakis (2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) and dianion of one the aliphatic dicarboxylic acids: butanedioic acid (succinic) acid = succH(2), pentanedioic (glutaric) acid = gluH(2), hexanedioic acid (adipic) acid = adipH(2) or decanedioic acid (sebacic) acid = sebH(2) of general formula [Co-2(L)(tpmc)](ClO4)(2)center dot xY, L2- = succ, x = 1, Y = H2O; L = glu, x = 1, Y = H2O; L = adip, x = 1.5, Y = H2O; L = seb, x = 1, Y = CH3CN were isolated. The composition and charge are proposed based on elemental analyses (C, H. N) and electrical conductivity measurements. UV-Vis and FTIR spectral data and magnetic moments were in accordance with high-spin Co(II) state. It is proposed that in all complexes Co(II) is hexa-coordinated out of cyclam ring and that both carboxylic groups from dicarboxylate bridge participate in coordination. Oxygens from one group are most likely bonded to the same Co(II) ion thus forming a four-membered ring. The in vitro antibacterial/antiproliferative activities of the complexes were in some cases enhanced compared with the simple Co(II) salt and free ligands, tested as controls

Preparation, characterisation and study of in vitro biologically active azamacrocyclic Cu(II) dicarboxylate complexes

New cationic Cu(II) complexes with N, N', N '', N'''-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) and aliphatic dicarboxylic acids: pentanedioic (glutaric acid = glutH(2)), hexanedioic acid (adipic acid = adipH(2)) and decanedioic acid (sebacic acid = sebH(2)) of general formula [Cu-4(L)(tpmc)(2)] (ClO4)(6)center dot xH(2)O, L = glut, x = 2; L = adip, x = 7; L = seb, x = 6 were isolated. Their composition and charges are proposed based on elemental analyses and molar conductivity measurements. By the comparison of their UV-Vis, reflectance, FTIR and EPR spectral data, CV and SQUID magnetic measurements, with those for the complex with butanedioic acid (succinic acid = succH(2)) of known molecular structure and analysis of LC/MS spectra, geometry with two [Cu(2)tpmc](4) units bridged by dicarboxylate dianion engaging all oxygens is proposed. Within units, Cu(II) ions are also bridged with -N- portion of cyclam ring. All four complexes were screened to in vitro antimicrobial and cytotoxic activity along with free primary and secondary ligands, Cu(II) salt and solvent controls. Detected antibacterial and cytotoxic activity for the complexes was enhanced in most cases than the corresponding controls

Correlations between the in vitro antiproliferative activity, structure and thermal stability of some macrocyclic dinuclear Cu(II) complexes

Seven macrocyclic dinuclear Cu(II) complexes with tpmc = N,N',N",N'"-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane of coordination formulae [Cu2tpmc](ClO4)4 (1), [Cu2(X)tpmc](ClO4)3•nH2O, X= F-, n = 0 (2), X = Cl-, n = 1 (3), X = Br-, n = 0 (4), X= I-, n = 1 (5), X = NO2-, n = 0 (6), [Cu2(NCS)2tpmc](ClO4)2 (7) were evaluated for their cytotoxic activity against human cervix adenocarcinoma (HeLa), human melanoma (Fem-x) and human colon carcinoma (LS174) cell lines. The results were compared with the corresponding data for the cis-dichlorido-diammineplatinum(II) (CDDP) as referent cytostatic together with the free ligands and solvent dimethyl sulfoxide (DMSO) as controls. The complexes showed considerable antiproliferative effect, although significantly less than CDDP. The thermal decomposition pattern of the complexes was determined by simultaneous TG/DSC measurements. The thermal stability of the compounds 2-7 followed the trend of their antiproliferative activity against HeLa cell line, as well as their corresponding stability constants. The highest thermal stability and cytotoxicity belonged to complex [Cu2tpmc](ClO4)4, with no anionic co-ligand. Complex [Cu2(NO2)tpmc](ClO4)3 exhibited a selective cytotoxicity against LS174 cells, at the level of the most active [Cu2tpmc](ClO4)4. [Projekat Ministartsva nauke Republike Srbije, br. 172014 i br. 175011

Synthesis of antimicrobial monophase silver-doped hydroxyapatite nanopowders for bone tissue engineering

Monophase silver-doped hydroxyapatite (AgxCa10-x(PO4)(6)(OH)(2); 0.002 lt = x lt = 0.04) nanoparticles were prepared using a neutralization method and investigated with respect to potential medical applications. This method consists of dissolving Ag2O in solution of H3PO4, and the slow addition to suspension of Ca(OH)(2) was applied for the purpose of homogenous distribution of silver ions. Characterization studies from XRD, TEM and FTIR spectra showed that obtained crystals are monophase hydroxyapatites and that particles of all samples are of nano size, with average length of 70nm and about 15-25nm in diameter. Antimicrobial studies have demonstrated that all silver-doped hydroxyapatite samples exhibit excellent antimicrobial activity in vitro against the following pathogens: Staphylococcus aureus, Escherichia coli and Candida albicans. The hydroxyapatite sample with the highest content of silver has shown the highest antimicrobial activity; killed all cells of E. coli and brought to more than 99% reduction in viable counts of S. aureus and C. albicans. The atomic force microscopic studies illustrate that silver-doped hydroxyapatite sample causes considerable morphological changes of microorganism cells which might be the cause of cells' death. Hemolysis ratios of the silver-doped hydroxyapatite samples were below 3%, indicating good blood compatibility and that are promising as biomaterials. Crown Copyright (C) 2010 Published by Elsevier B. V. All rights reserved