Search results for " voltammetry"
showing 10 items of 295 documents
An Iron-Based Molecular Redox Switch as a Model for Iron Release from Enterobactin via the Salicylate Binding Mode
2001
The iron release mechanism from protonated ferric enterobactin [Fe(III)(enterobactinH(3))] via the salicylate binding mode was probed. For this purpose, a tripodal dodecadentate ligand incorporating three salicylamide (OO) and three bipyridine (NN) binding sites was synthesized as well as iron complexes thereof. It was shown that a ferric ion coordinates selectively to the hard salicylamides and a ferrous ion binds to the softer bipyridines. Upon reduction or oxidation, the iron translocates reversibly and intramolecularly from one site to the other, thus displaying switchlike properties. Both states were characterized by cyclic voltammetry and visible and Mössbauer spectroscopy. The Mössba…
Recent Approaches for Chemical Speciation and Analysis by Electrospray Ionization (ESI) Mass Spectrometry
2021
In these latest years, the chemical speciation of several species has been increasingly monitored and investigated by means of electrospray ionization mass spectrometry (ES-MS). This soft ionization technique is capable to gently take into the gas phase metal-ligand complexes and gather a wealth of information on their energetics, shape, and fragmentation pathways. For this reason, this technique is frequently chosen in a synergistic approach to investigate competitive ligand exchange-adsorptive other ways analyzed by cathodic stripping voltammetry (CLE-ACSV). ESI-MS analyses require a careful experimental design as they may be impacted by instrumental artifacts such as ESI adduct formation…
"Sweet Chemistry": a Green Way for Obtaining Selenium Nanoparticles Active against Cancer Cells
2017
We present an environment friendly synthesis of selenium nanoparticles and the study of their cytotoxic activity against uterine sarcoma cancer and fibroblasts cells. Amorphous selenium (a-SeNPs) and trigonal selenium (t-SeNPs) were synthesized using D-fructose as the reducing agent and characterized by high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction analysis (XRD), inductively coupled plasma optical emission spectrometry (ICP OES), dynamic light scattering (DLS) to obtain zeta potential values and cyclic voltammetry (CV). Particularly, a-SeNPs presented high toxicity toward the resistant cancer cell line MES-SA/…
Synthesis and electrochemical study of a new doubly-metallated compound with the ferrocene-labelled phosphine PPh2(C5H4)Fe(C5H5)
1993
Abstract Direct reaction of the metalled compound Rh 2 (μ 2 -O 2 CCH 3 ) 3 [μ 2 -(C 6 H 4 ) PPh 2 ]·(H 2 O) 2 with PPh 2 Fc [Fc = (C 5 H 4 )Fe(C 5 H 5 )] in chloroform solution yields the corresponding mono-adduct Rh 2 (O 2 CCH 3 ) 3 [(C 6 H 4 )PPh 2 ]·(PPh 2 Fc) ( 1 ), which has been characterized by 31 P NMR spectroscopy. Photochemical irradiation of 1 in chloroform gives the compound Rh 2 (μ-O 2 CCH 3 ) 2 (η 2 -O 2 CCH 3 )[μ 2 -(C 6 H 4 )PPh 2 ][PPh 2 Fc]·(H 2 O) ( 2 ) in practically quantitative yield. Compound 2 , by thermal treatment in chloroform solution, yields cleanly the doubly-metallated compound Rh 2 (μ 2 -O 2 CCH 3 ) 2 [μ 2 -(C 6 H 4 )PPhFc][μ 2 -(C 6 H 4 )PPh 2 ]·(H 2 O) 2 ( …
Channel flow at an immobilised liquid|liquid interface
2000
A novel rectangular channel flow electrochemical cell for the study of liquid | liquid interfaces is presented. The organic phase is immobilised by the use of a gelling agent, while the aqueous phase flows past the interface. This creates an asymmetric setup that allows us to establish diagnostic criteria to determine, for example, the direction of the ion transfer. The effects of varying flow rate and sweep rate have been considered both theoretically and experimentally. By comparison with two-dimensional simulations, it is demonstrated that a simple one-dimensional theory can be used to describe the cyclic voltammetry response of the channel flow cell.
Reduction of ferricytochrome c catalyzed by optically active chromium(III) complexes
2009
The reduction rates of horse heart ferricytochrome c by amalgamated zinc or by electrolysis at fixed potential on a mercury pool as the cathode have been measured in a buffered solution at pH 7.5 by absorption spectrophotometry. In both cases, the reaction was strongly accelerated by the presence of the optically active complexes Lambda-[Cr(III)((S,S)-promp)H(2)O](+) (H(2)promp = N,N'-[(pyridine-2,6-diyl)bis(methylene)]-bis[(S)-proline]), Delta-[Cr(III)((R,R)-alamp)H(2)O](+) (H(2)alamp = N,N'-[(pyridine-2,6-diyl)bis(methylene)]-bis[(R)-alanine]) and Lambda-[Cr(III)((S,S)-alamp)(H(2)O)(2)](+). These were shown to undergo reversible one-electron reduction to the corresponding labile chromium(…
Spectroscopic and electrochemical study of interactions between DNA and different salts of 1,4-dihydropyridine AV-153
2020
1,4-dihydropyridines (1,4-DHP) possess important biochemical and pharmacological properties, including antimutagenic and DNA-binding activity. The latter activity was first described for water-soluble 1,4-DHP with carboxylic group in position 4, the sodium salt of the 1,4-DHP derivative AV-153 among others. Some data show the modification of physicochemical properties and biological activities of organic compounds by metal ions that form the salts. We demonstrated the different affinity to DNA and DNA-protecting capacity of AV-153 salts, depending on the salt-forming ion (Na, K, Li, Rb, Ca, Mg). This study aimed to use different approaches to collate data on the DNA-binding mode of AV-153-N…
Synthesis, photochemistry, and electrochemistry of (P)Ge(R)2 and (P)Ge(R)X (P = TPP or OEP, R = CH3, CH2C6H5, or C6H5, and X = Cl-, OH-, or ClO4-)
1987
Chaque complexe est caracterise par spectroscopie RMN de H1, UV-visible, IR et aussi par l'etude electrochimique
Pb(II) adsorption by a novel activated carbon - alginate composite material. A kinetic and equilibrium study.
2016
The adsorption capacity of an activated carbon – calcium alginate composite material (ACAA-Ca) has been tested with the aim of developing a new and more efficient adsorbent material to remove Pb(II) ion from aqueous solution. The study was carried out at pH = 5, in NaCl medium and in the ionic strength range 0.1–0.75 mol L−1. Differential Pulse Anodic Stripping Voltammetry (DP-ASV) technique was used to check the amount of Pb(II) ion removed during kinetic and equilibrium experiments. Different kinetic (pseudo first order, pseudo second order and Vermuelen) and equilibrium (Langmuir and Freundlich) models were used to fit experimental data, and were statistically compared. Calcium alginate …
Evaluation of the electrochemical anion recognition ofNO3−-imprinted poly(Azure A) inNO3−/Cl−mixed solutions by ac-electrogravimetry
2016
Abstract During the reversible electrochemical reactions of the intrinsically conducting polymer (ICP) films, ions are inserted in them to balance the inner charge site of the polymer. For this reason, doped ICP films with anions or cations can be good candidates for the electrochemical removal of contaminant ions from wastewater. In this work, a polymer of a phenothiazine derivative (poly(Azure A or PAA)) was electrosynthesized by cyclic voltammetry in aqueous solutions using nitrate ions as a structural template. After that, PAA film was repeatedly cycled in identical conditions in a monomer-free solution. The electrochemical anion recognition of the nitrate-imprinted poly(Azure A) ( N O …