Reducing Antioxidant Capacity Evaluated by Means of Controlled Potential Electrolysis

An analytical method suitable for an antioxidant sensor is presented following the response of these substances to an extensive oxidation imposed by electrochemical means. The electrochemical assay simulates the action of a reactive oxygen species (ROS) by means of electrolyses carried out at a potential which is settled at the formal potential of the ROS. The antioxidant activities of trolox and ascorbic, gallic and caffeic acids and of mixtures of these antioxidants were estimated from the charge required for the complete oxidation of the antioxidants from assays where the oxidative attack by O₂ and by O₂^.? were simulated.     

Synthesis and characterization of [chloro{2(1H)-pyridinethione-S}{tris(pyridin-2-ylthiolato)methyl-C,N,N′,N″]}nickel(II)], [Ni(TPTM)(SPyH)Cl]

The compound, [chloro{2(1H)-pyridinethione-S}{tris(pyridin-2-ylthiolato)methyl-C,N,N′,N″]}nickel(II)], [Ni(TPTM)(SPyH)Cl], was isolated from the reaction between NiCl₂ · 6H₂O and tris(pyridin-2-ylthiolato)methane in aqueous EtOH. X-ray crystallography at 120 K revealed an octahedral arrangement about Ni with a tetradentate tris(pyridin-2-ylthio)methyl-C,N,N,N ligand, a monodentate 2(1H)-pyridinethione-S ligand and a chloride. The 2(1H)-pyridinethione-S ligand was derived from tris(pyridin-2-ylthio)methane probably via an acid catalysed hydrolysis reaction. Intramolecular N–H–Cl and C–H–Cl interactions help to cement the molecular structure. Weak C–H–Cl and C–H–S hydrogen bonding interactions link molecules of [Ni(TPTM)(SPyH)Cl] into a 3D array. EPR and UV spectra, and Hartree–Fock theoretical calculations are reported.     

Formation and crystal structures of [(alkoxy)bis(pyridin-2-yl)methanolato-N,O,N]tin(IV) complexes

Reactions of bis(pyridin-2-yl)ketone with tin tetrahalides, SnX₄ (X = Cl or Br), or organotin trichlorides, R^′SnCl₃ (R^′ = Ph, Bu or CH₂CH₂CO₂Me), in ROH (R = Me or Et) readily produces RObis(pyridin-2-yl)methanolato)tin complexes, [5: RO(py)₂C(OSnX₃)] (5: R,X = Me,Cl; Et,Cl; Et,Br) or [6: MeO(py)₂C(OSnCl₂R^′)] (R^′ = Ph, Bu, CH₂CH₂CO₂Me). In addition, halide exchange reaction between SnI₄ and (5: R,X = Me,Cl) occurred to give (5: R,X = Me,I). The crystal structures of six tin(IV) derivatives indicated, in all cases, a monoanionic tridentate ligand, [RO(py)₂C(O⁻)-N,O,N], arranged in a fac manner about a distorted octahedral tin atom. The Sn–O and Sn–N bonds lengths do not show much variation amongst the six complexes despite the differences in the other ligands at tin.     

Complete latticeability in vector-valued sequence spaces

Using a technique due to Jiménez–Rodríguez, first we prove the complete latticeability of the set of disjoint non-norm null weakly null sequences and of the set of disjoint non-norm null regular-polynomially null sequences in Banach lattices. Then we apply the mother vector technique to prove the complete latticeability of ${\lambda }_{\pi }(E)\setminus {\lambda }_s(E)$, which implies the complete latticeability of $({\ell }_p{\widehat{\otimes }}_{|\pi |}E)\setminus ({\ell }_p{\widehat{\otimes }}_{\pi }E)$, where E is a Banach lattice and .