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Abstract: The first [5+5] coordination isomer of a zinc helical dimer derived from a pentadentate bisthiosemicarbazone Schiff base ligand was obtained by means of a new route. This compound was synthesised using a template procedure, spectroscopically characterised and recrystallised in a 1:1 v/v dichloromethane/acetonitrile mixture. The geometry showed by this compound is new for well-known dimer zinc complexes derived from pentadentate thiosemicarbazones and suggests that the experimental procedure could be an important factor in defining the stereochemistry of the metal atoms in such helical dimers. [Copyright &y& Elsevier]

The electrochemical oxidation of a tin plate in the presence of an acetonitrile suspension of the ligand bis-(4-N-methylthiosemicarbazone)-2,6-diacetylpyridine, H4DAPTsz-Me, yields the complex Sn(H2DAPTsz-Me)(H2O)2 (1). Recrystallisation of 1 in a methanol/acetone solution leads us to isolate yellow crystals of [Sn(H2DAPTsz-Me)(CH3OH)2] · CH3OH (2), structurally characterised. To the best of our knowledge, 2 is the first neutral Sn(II) complex derived from a pentadentate thiosemicarbazone Schiff base ligand. This complex shows a distorted pentagonal bipyramidal geometry for Sn(II), being the metal surrounded by the N3S2 donor set of the bideprotonated ligand [H2DAPTsz-Me]2−. This compound self-assembles into a 3D network through intermolecular hydrogen bonds. [Copyright &y& Elsevier]

In this work, four manganese(II) complexes derived from the ligands H 2 L1-H 2 L4, that incorporate dansyl or tosyl fluorescent dyes, have been investigated in term of their antioxidant properties. Two of the manganese(II) complexes have been newly prepared using the asymmetric half-salen ligand H 2 L2 and the thiosemicarbazone ligand H 2 L3. The four organic strands and the manganese complexes have been characterized by different analytical and spectroscopic techniques. The study of the antioxidant behaviour of these two new complexes and other two fluorophore-labelled analogues was tested in SH-SY5Y neuroblastoma cells. These four model complexes 1 – 4 were found to protect cells from oxidative damage in this human neuronal model, by reducing the release of reactive oxygen species. Complexes 1 – 4 significantly improved cell survival, with levels between 79.1 ± 0.8% and 130.9 ± 4.1%. Moreover, complexes 3 and 4 were able to restore the mitochondrial membrane potential at 1 μM, with 4 reaching levels higher than 85%, similar to the percentages obtained by the positive control agent cyclosporin A. The incorporation of the fluorescent label in the complexes allowed the study of their ability to enter the human neuroblastoma cells by confocal microscopy. Four manganese complexes that incorporate fluorescent dyes can protect cells from oxidative damage, induce a decrease in reactive oxygen species (ROS) release and ameliorate the mitochondrial function in a human neuronal model. The incorporation of the fluorescent labels allows the study of the ability of the complexes to enter cells. [Display omitted] • Four manganese complexes with fluorescent dyes behave like catalytic antioxidants. • Complexes improve cell survival against oxidative stress in a human neuronal model. • Complexes induce a significant decrease in reactive oxygen species release. • Two of the complexes can restore the mitochondrial membrane potential. • Fluorescent labels allow the study of the ability of the complexes to enter cells. [ABSTRACT FROM AUTHOR]

Abstract: The interaction of manganese(II) carboxylate salts [Mn(O2CR)2, where R=ethane, pentane] with H2L1 [N,N′-bis(3-methoxy-2-hydroxybenzaldehyde)-1,2-phenylenediamine] and H2L2 [N,N′-bis(3-ethoxy-2-hydroxybenzaldehyde)-1,2-phenylenediamine] was studied. MnL1(O2CEt)(H2O) (1), MnL1(O2CPe n )(H2O) (2), MnL2(O2CEt)(H2O)2 (3) and MnL2(O2CPe n )(H2O)2 (4) were isolated and thoroughly characterised by elemental analysis, FAB mass spectrometry, infrared and 1H NMR spectroscopy, magnetic susceptibility measurements, molar conductivities, and cyclic and normal pulse voltammetry. Compounds 1 and 2 were crystallographically characterised revealing a tetragonally elongated octahedral geometry for the manganese coordination sphere and also a dimeric nature through μ-aqua bridges. Complexes 1–4 behave as efficient peroxidase mimics in the presence of the water-soluble trap ABTS, probably due to their ease to coordinate the substrate molecule. A correlation between rhombicity of the complexes and peroxidase activity has also been established. [Copyright &y& Elsevier]

A series of phosphino-thiosemicarbazone gold(I) dinuclear complexes obtained by two different synthetic procedures have been prepared. All the compounds have been spectroscopically characterized including single crystal X ray diffraction analysis in some of cases. [Au 2 (HL 1 )Cl 2 (1), [Au 2 (HL 2 ) 2 Cl 2 (2) and [Au 2 (HL 3 ) 2 Cl 2 (3) have been prepared by chemical synthesis using a gold(III) salt as precursor; while [Au 2 (L 1 ) 2 (4), [Au 2 (L 2 ) 2 ∙2CH 3 CN (5) and [Au 2 (L 3 ) 2 (6) have been isolated from an electrochemical synthesis (HLn = 2-[2-(diphenylphosphanyl)-benzylidene]- N -R-thiosemicarbazone; HL1: R = methyl, HL2: R = methoxyphenyl, HL3: R = nitrophenyl). The in vitro cytotoxic activity of these gold(I) complexes was tested against some human tumor cell lines: HeLa 229 (cervical epithelial carcinoma), MCF-7 (ovarian adenocarcinoma), NCI-H460 (non-small-cell lung cancer) and MRC5 (normal human lung fibroblast), and the IC 50 values compared with those of cisplatin. The neutral methyl-substituted complexes 1 and 4 and methoxyphenyl 5 displayed significant cytotoxic activities in all investigated cancer cell lines, being 1 and 4 the most effective. The ability of complexes 1 and 4 to induce cell death by apoptosis in Hela 229 was also investigated by fluorescence microscopy using the apoptotic DNA fragmentation as marker. These results indicated that the inhibition of cell proliferation is mainly due to an apoptotic process. In order to obtain more information about the mechanism of action of these metallocompounds, the interactions of complexes 1 and 4 with the thioredoxin reductase (TrxR) enzyme were analyzed. Both complexes exhibited a strong inhibition of the thioredoxin reductase activity. Unlabelled Image • Gold(I) complexes obtained by traditional and a electrochemical procedures were studied. • Electrochemical synthesis makes available a new arsenal of neutral gold(I) compounds. • Complexes containing the methyl group are the most cytotoxic against the investigated cancer cell lines. • These complexes exhibit a strong inhibition of the thioredoxin reductase activity. [ABSTRACT FROM AUTHOR]