Search results for "complexe"
showing 10 items of 920 documents
Dimer complexes of 2,4-toluenediamine-N,N,N′,N′-tetraacetic acid (2,4-TDTA) with copper(II), nickel(II), cobalt(II), zinc(II) and manganese(II). Stud…
1997
Abstract Potentiometric investigations in aqueous solution at 25°C and ionic strength 0.1 mol dm−3 KCl show that 2 2,4-toluenediamine-N,N,N′N′-tetraacetic acid (2,4-TDTA) forms with Cu(II), Ni(II), Co(II), Zn(II) and Mn(II) the following complexes (ligand, H4L): monomers [MH2L], [MHL]− and [ML]2−; dimers [M2HL2]3− and [M2L2]4−; with excess of ligand [MH2L2]4−, [MHL2]5− and [ML2]6− (Cu(II), Ni(II) and Zn(II)) and with excess of metal [M2HL]+ (Ni(II), Co(II)and Mn(II) and [M2L] (Cu(II)). The formation constants of the complexes have been determined. The species distribution diagrams indicate that a concentrated solution with a ligand:metal ratio 1:1 at pH 6 is suitable for the synthesis of cr…
Complex Formation of the Uranyl (UO22+) Ion with the Diethylene Triaminopentaacetate (DTPA) Ligand at 25 °C in 3 M Sodium Perchlorate
2011
The complex formation between the uranyl (UO22+) ion and the diethylene triaminopentaacetate ligand (DTPA) has been investigated at 25 °C, in a 3 M sodium perchlorate medium. The overall protonation constants βjH of the free ligand have been previously determined in this ionic medium: six protonated species (HjA), with j ranging from 1 to 6, together with the free anion A5− have been identified in the concentration range from (3·10−3 to 13·10−3) mol·kg−1. Four complex species, H2UO2A−, HUO2A2−, UO2A3−, and UO2AOH4−, have been identified in the total uranyl concentration range from (1.1·10−3 to 5.7·10−3) mol·kg−1, and their overall stability constants determined, keeping the metal to ligand …
Potentiometric and spectroscopic studies of transition-metal ions complexes with a quinolone derivative (cinoxacin). Crystal structures of new Cu(II)…
1997
Abstract The interaction of cobalt(II), nickel(II), copper(II), and zinc(II) with Cinoxacin (HCx = 1-ethyl-1,4-dihydro-4-oxo(1,3)dioxolo(4,5-g)cinnoline-3-carboxylic acid), a 4-quinolone derivative, has been studied at metal/ligand ratios of 1:1-1:3 by means of pH-metric, spectrophotometric, and ESR methods. The formation constants have been determined and the stereochemistry for the metal ions in the species present in aqueous solutions (at 37 ± 0.1°C and I = 0.1 mol dm −3 NaCl) is discussed. In all the studied systems, complexes with different stoichiometric ratios, in which cinoxacin acts both as neutral and deprotonated ligand, are formed. The anomalous sequence of the stepwise stabilit…
Evaluation of the sequestering ability of different complexones towards Ag+ ion
2014
Abstract The interaction between Ag+ cation and different ligands was evaluated as a function of temperature and ionic strength by means of potentiometric techniques. Six aminopolycarboxylic (APCs) and aminopolyphosphonic (APPs) ligands were chosen, namely four APCs: nitrilotriacetic acid (NTA), ethylene-glycol-bis(2-aminoethylether)-N,N,N’,N’-tetraacetic acid (EGTA), ethylenediamine-N,N,N’,N’-tetraacetate (EDTA) and diethylenetriamine-N,N,N’,N”,N”-pentaacetic acid (DTPA)] and two APPs: [(1-hydroxyethane-1,1-diyl)bis(phosphonic acid) (HEDP) and [[(Phosphonomethyl)imino]bis[2,1-ethanediylnitrilobis(methylene)]] tetrakis-phosphonic acid (DTPP). Different mononuclear species with general formu…
A dinucleating ligand which promotes DNA cleavage with one and without a transition metal ion.
2013
The dinucleating ligand L (1,3-bis[bis(pyridin-2-ylmethyl)amino]propan-2-ol) combined with metal ions efficiently cleaves DNA when M : L is 1 : 1 (M = Co(II) or Fe(III)) at pH 5.5–7.0, with free L being more active at acidic pH than when bound to Zn(II), Cu(II) or Ni(II) at neutral pH.
Alkyl and aryl substituted corroles. 3. Reactions of cofacial cobalt biscorroles and porphyrin-corroles with pyridine and carbon monoxide.
2002
The synthesis and characterization of three new cofacial biscorroles and three new linked Co(II) porphyrins and Co(III) corroles with the same face to face orientation are described. The biscorroles are represented as (BCS)Co(2), (BCO)Co(2), (BCX)Co(2) while the porphyrin-corrole dyads are represented as (PCA)Co(2), (PCB)Co(2), (PCO)Co(2) where BC represents the Co(III) cofacial biscorroles and PC represents the porphyrin-corrole complexes which are linked to each other by a dibenzothiophene (S), dibenzofuran (O), or 9,9-dimethylxanthene (X) bridge in the case of the corroles and an anthracene (A), biphenylene (B), or dibenzofuran (O) bridge in the case of the mixed macrocycle derivatives. …
Human Hsp60 with Its Mitochondrial Import Signal Occurs in Solution as Heptamers and Tetradecamers Remarkably Stable over a Wide Range of Concentrati…
2014
It has been established that Hsp60 can accumulate in the cytosol in various pathological conditions, including cancer and chronic inflammatory diseases. Part or all of the cytosolic Hsp60 could be naive, namely, bear the mitochondrial import signal (MIS), but neither the structure nor the in solution oligomeric organization of this cytosolic molecule has still been elucidated. Here we present a detailed study of the structure and self-organization of naive cytosolic Hsp60 in solution. Results were obtained by different biophysical methods (light and X ray scattering, single molecule spectroscopy and hydrodynamics) that all together allowed us to assay a wide range of concentrations of Hsp60…
Fluorescent metal-based complexes as cancer probes.
2020
Abstract The ability to track drugs inside of cells and tumours has been highly valuable in cancer research and diagnosis. Metal complexes add attractive features to fluorescent drugs, such as targeting and specificity, solubility and uptake or photophysical properties. This review focuses on the latest fluorescent metal-based complexes, their cellular targets, photophysical properties and possible anticancer effects.
Insertion of light-harvesting chlorophyll a/b protein into the thylakoid
2000
The major light-harvesting chlorophyll a/b-binding protein (Lhcb1,2) of photosystem II is inserted into the thylakoid via the signal recognition particle dependent pathway. However, the mechanism by which the protein enters the membrane is at this time unknown. In order to define some topographical restrictions for this process, we constructed several recombinant derivatives of Lhcb1 carrying hexahistidine tags at either protein terminus or in the stromal loop domain. Additionally, green fluorescent protein (GFP) was fused to either terminus. None of the modifications significantly impair the pigment-binding properties of the protein in the in vitro reconstitution of LHCII. With the excepti…
Predictive First-Principles Modeling of a Photosynthetic Antenna Protein: The Fenna–Matthews–Olson Complex
2020
High efficiency of light harvesting in photosynthetic pigment–protein complexes is governed by evolutionary-perfected protein-assisted tuning of individual pigment properties and interpigment interactions. Due to the large number of spectrally overlapping pigments in a typical photosynthetic complex, experimental methods often fail to unambiguously identify individual chromophore properties. Here, we report a first-principles-based modeling protocol capable of predicting properties of pigments in protein environment to a high precision. The technique was applied to successfully uncover electronic properties of the Fenna–Matthews–Olson (FMO) pigment–protein complex. Each of the three subunit…