Search results for "HeLa"
showing 10 items of 738 documents
Influence of structural elements on iron(III) chelating properties in a new series of amino acid-derived monohydroxamates
2018
Abstract A series of amino acid-derived monohydroxamate compounds A1 – A7 was synthesized and characterized for their coordination properties of Fe(III). The series varies in their skeletal lengths and compositions; some compounds lack external substituents, others are substituted with external functional amino or carboxylic groups, or alternatively inert methyl. Undertaken investigations allowed the determination of stoichiometry, stability constants and spectroscopic parameters of formed ferric complexes. Incorporation of an external functional group with a dissociable proton affects the coordination behavior; the presence of carboxylic or amino groups hampers the formation of mono-, di- …
Structural diversity of copper(II) amino alcoholate complexes
2017
Abstract Amino alcohols which carry both amino and hydroxyl groups in the same molecule are good chelating and bridging ligands. They have been broadly used for the preparation of copper(II) amino alcoholate complexes through the self-assembly process, which generally leads to the formation of diverse structures from mononuclear to polynuclear copper(II) clusters. There are three main factors to control the nuclearity of these clusters: (i) the molar ratio of Cu(II) to amino alcohol, (ii) the choice of the counter anions and (iii) the nature of the amino alcohol. These structures can be used as model systems in magnetic studies, allowing a better understanding about the magnetic interaction…
Copper(II) and nickel(II) complexes of pyridylamido hexadentate ligands: chemical speciation and spectroscopic studies
2003
Abstract Two novel potentially hexadentate ligands, 1,10-(2-bis picolinamide)-4,7-diazadecane (pycdpnen) and 1,8-bis(2-picolinamide)-3,6-dioxaoctane (pycdado) have been synthesised as their hydrochloride salt; its protonation constants and the stability constants of the copper(II) and nickel(II) chelates have been determined by potentiometry. Amide groups deprotonation permits the formation of [MLH −1 ] + species in all cases, while only pycdado gives [MLH −2 ] species. The solid complexes of copper and nickel with the neutral and the deprotonated ligands have been synthesised and characterised by IR, UV–Vis and ESR spectroscopy. The amidic groups are coordinated through the oxygen atoms in…
Thermodynamic studies of iron(III) complex of some new dihydroxamic acids model of rhodotorulic acid
2018
Abstract The objective of this research is to elucidate the coordination chemistry and the structure of complexes formed with siderochelates organic ligands and the physico-chemical studies of iron(III) complexation. Three dihydroxamic acids synthesized ((LCyEt)2−, (LCyPr)2− and (LO)2−) mimicking a fungal siderophore, rhodotorulic acid. They were evaluated with iron(III) chelation by potentiometric and spectrophotometric titrations in 0.1 M KNO3. These measurements revealed the formation of dileptic and trileptic complexes in excess ligand conditions. The chemical model includes five species of [Fem(L)lHh](3m−2l+h)+ with general formula: [Fe(L)]+, [Fe(L)(OH)], [Fe(L)(OH)2]−, [Fe(L)2H] and […
Characterization of β-B-Agostic Isomers in Zirconocene Amidoborane Complexes
2009
The reaction of Cp(x)(2)ZrCl(2) (Cp(x) = Cp, Cp*) with ammonia borane in presence of n-butyllithium yielded Cp(2)Zr(Cl)NH(2)BH(3) and Cp(x)(2)Zr(H)NH(2)BH(3). These derivatives are isoelectronic with the ethyl zirconocene chloride and hydride, respectively, and feature a chelating amidoborane ligand coordinating through a Zr-N bond and a Zr-H-B bridge. In solution, each of the complexes consists of an equilibrium mixture of two isomers differing in the orientation of the amidoborane ligand with respect to the Zr-X bond (X = H, Cl), while in the solid state, only one isomer was observed. Such isomers have not been characterized for any metal complexes containing the isoelectronic beta-agosti…
Chromatography of metal chelates
1973
The chromatographic behavior of metal bis(ethoxyethyl)dithiocarbamate was investigated. The chelates of 14 elements (V, Cr, Co, Ni, Cu, Zn, Se, Mo, Cd, Te, Hg, Tl, Pb and Bi) could be preconcentrated from water with an on-line system and were shown to be suitable for C18-reversed-phase liquid chromatography. A quaternary solvent mixture with admixture of a surfactant was used as eluent, UV-detection was performed at 254 nm. Thermostating the column to 40° C resulted in a significant increase in chromatographic resolution and in a decrease of analysis time. The recovery of the chelates from the aqueous solutions as well as reproducibility of the results are very sensitive to pH changes.
A novel bisphosphonate-based solid phase method for effective removal of chromium(iii) from aqueous solutions and tannery effluents
2013
Effective removal of chromium(III) from waste waters e.g. in the leather industry is required due to continuously tightening environmental regulations, and several methods such as precipitation and adsorption are currently in use. Nevertheless, more efficient, straightforward and inexpensive methods are constantly being sought. The current study describes a novel method to separate chromium(III) from aqueous solutions based on the use of solid bisphosphonates with a P–C–P backbone. Five classes of bisphosphonates with different functional groups and alkyl chain lengths at the center carbon, in all 16 compounds, were prepared and their suitability for metal ion complexing as chelating agents…
New phenolics, cytotoxicity and chemosystematic significance of Atriplex semibaccata
2019
Abstract The chemical characterization of the 70% hydromethanolic extract of Atriplex semibaccata (family: Chenopodiaceae) afforded a new methoxylated flavonol triglycoside, atrisemibaccatoside A (1), and a new lignanamide, (N-[(E)-m-hydroxycinnamoyl]tyramine (7), as well as, five known flavonols (2–6) and two lignanamides (8–9). The structures of the isolated compounds were established depending upon LR&HR-FAB-MS, 1D and 2D NMR spectroscopic analyses. The cytotoxic activity of the isolated compounds (1–4, and 7–9) was investigated. Compounds 7, 8 and 9 weakly inhibited the proliferation of leukemia CCRF-CEM cells with IC50 values of 78.5, 46.3, and 71.2 μg/ml, respectively, and exhibited n…
Complexes of organometallic compounds
1972
Abstract The novel organobismuth(V) derivatives Ph 3 BiCl(Ox) and Ph 3 BiBr(Ox) (Ox − = 8-quinolinate) have been synthesized, and their configuration investigated in the solid state and in solution. The complexes are assumed to be octahedral in the solid, with Ox − acting as a chelating base and the halide atoms coordinating to bismuth. Tentative assignments of infrared bands in the 300–80 cm −1 region to BiHal and other skeletal modes are proposed. The main effect of solvents appears to be the weakening and breaking of BiN-bonds.
Effect of chelatants on gellan gel rheological properties and setting temperature for immobilization of living bifidobacteria.
1993
The effect of various concentrations of sequestrants (sodium citrate, sodium metaphosphate, and EDTA) was studied on gellan gel (1.5-2.5% (w/v)) setting temperature and rheological properties. Addition of EDTA between 0 and 0.8% (w/v) led to a progressive decrease of setting temperature. Citrate and metaphosphate decreased this parameter when added up to 0.4 or 0.6%, depending on gellan gum concentration, eventually resulting in the absence of gel formation at room temperature for the 1.5% gellan solution containing 0.4% citrate. This effect was accompanied by a significant decrease of gel strength and stiffness and might be attributed to the binding of the divalent cations required for cha…