Synthesis, structure and electrochemical properties of the cationic complex tris-(imidazolidine-1,10-phenanthroline)iron(II) (original) (raw)
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Electroanalysis, 2011
A new conducting film derived from the complex [Fe (diaphen) 3 ] 2 + , (diaphen = 5,6-diamino-1,10-phenanthroline) was electropolymerized by cyclic voltammetry onto a glassy carbon electrode. Poly-[Fe II (diaphen) 3 ] was studied by cyclic voltammetry, SEM, UV-vis and micro-Raman spectroscopy. Poly-[Fe II (diaphen) 3 ] shows electrocatalytic activity in HSO 3 À reduction in an ethanol/water solution. Electrocatalysis is centered at the p ring of phenanthroline. Rotating disk electrode studies showed a 0.117 V/dec Tafel slope, suggesting an EC process where the electrochemical process is the determining step. The chemical step was studied by UV-vis spectroelectrochemistry. Amperometric behavior showed a linear range between 47.5 mM to 417 mM and the LOD was 19.5 mM.
Monatshefte für Chemie Chemical Monthly, 1992
The acid-base properties of the g-oxo bridged dimeric iron complexes [FeL]20 with the ligands based on S-alkyl-l,4-bis(substituted salicylidene)isothiosemicarbazide and a tetramer with Smethyl-1,4-bis(salicylidene)isothiosemicarbazide, {[FeL]20}213.I2, were investigated by cyclic voltammetry at glassy carbon electrode in DMF. Studies were carried out in the presence of either a weak (phenol) or a strong (HC104 aq.) acid. The stoichiometry of the reaction, changes in the general voltammetric pattern and the electrode reaction mechanism were discussed. These studies served as the basis for three-electrode amperometric titrations to determine the content of several of these complexes.
Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 1987
The eMrodic oxidation of the cationic metal-chelated tris-1,10_phenanthroline iro4II) ion (Fe(ph)$+) was studied in the presence of the anionic surfactant dodecylsulphate (DC). Voltammetry at a platinum rotating disk electrode supported the conclusion that the interaction between Fe(ph)$+ and DS-leads, with increasing surfactant concentration, to: (i) the formation of a neutral electroinactive 1: 2 complex (&a = 2.5 X 10' on the molar scale); (ii) the precipitation of a coacervate phase (K,' = IFe(p HDS-1' = 6 X 10-'2) and (iii) to the micelle solubilixation of the metal chelate at post-cmc ~nc~tratio~. The analysis of the dependence of the limiting current upon rotation speed can be interpreted on the basis of a charge transfer process preceded by a first-order chemical reaction corresponding to the exit of Fe(ph) :+ from the micelle. The exit rate constant (kr) at fixed ionic strength ([Na2S04] = 0.05 mol 1-l) is independent of DS-concentration in the range 0.02-0.2 mol 1-l: kr = 2(k 1) x 10' s-l *. The effect of ionic strength (NasSO, added) and temperature on the limiting current has been investigated. fNTRODUCTTON * For a diffusion-controlled backward reaction.
Electrochemical behavior of iron(III) complexes with aminohydroxamic acids
Polyhedron, 2002
The electrochemical reduction of various aminohydroxamate complexes of iron(III), such as alanine-, serine-, lysine-, histidineand glutamo-g-hydroxamate, has been investigated in aqueous solution by cyclic voltammetry on hanging mercury drop electrodes to determine the mechanism involved in the electron transfer processes. In all the studied cases the iron(III) complexes, with the exception of histidinehydroxamate, have been found to undergo reversible reductions followed by irreversible chemical reactions (EC mechanism). Rate constants for the irreversible dissociation of iron(II) complexes were calculated. The typical quasi-reversible pattern for the reduction of histidinehydroxamate was attributed to the different coordination mode. The observed differences in redox potentials between the investigated complexes suggest that the electronic effect of the substituent on the carbonyl group, involved in the coordination to the iron center, may modify the donor properties of the oxygen atoms of the hydroxamate moiety. The potentials determined at physiological pH are in the range of biological reducing agents, which makes these compounds potential siderophore models. #
Synthesis, structure, magnetic and electrochemical properties of an oxydiacetate iron(II) complex
Inorganica Chimica Acta, 2004
2 ] has been obtained by reaction of FeCl 2 Á 4H 2 O with a 1:1 mixture of O(CH 2 COOH) 2 and Na 2 CO 3 in water. The structure is polymeric with concatenated {Fe(oda)(H 2 O) 2 } units extended in one direction. Each iron centre is six-coordinated by the tridentate planar oda ligand, two mutually trans water molecules and one oda oxygen atom from an adjacent {Fe(oda)(H 2 O) 2 } unit. Complex 1 is isomorphous with cobalt and zinc analogues. Magnetic susceptibility measurements down to 2 K showed high-spin non-correlated Fe(II) ions with a typical Curie-Weiss behaviour. Differential-pulse voltammetry establishes a value of 0.488 V versus NHE for the Fe(III)/Fe(II) redox potential of this iron complex in 0.25 mol dm À3 NaNO 3 .
Journal of Molecular Catalysis A: Chemical, 2009
Tridentate Schiff base ligands derived from aromatic aldehydes and benzhydrazide, and their iron complexes [Fe(L 1 )(HL 1 )] 1, [Fe(HL 1 )Cl 2 (CH 3 OH)]·(CH 3 OH) 2 and [Fe(HL 2 )Cl 2 (H 2 O)] 3 have been prepared and characterized (H 2 L 1 = (E)-N -(2-hydroxy-3-methoxybenzylidene)benzohydrazide, H 2 L 2 = (E)-N -(5bromo-2-hydroxybenzylidene)benzohydrazide). The crystal structure of 2 has been determined. The electrochemical properties of these complexes have been investigated by cyclic voltammetric technique in acetonitrile solutions. Electrochemical studies have revealed quasi-reversibility for these compounds. The catalytic potential of these complexes has been tested for the oxidation of cyclooctene using tert-butylhydroperoxide (TBHP) as oxidant. The effects of the molar ratio of oxidant to substrate, the temperature, the co-catalyst concentration and the solvent have been studied. Excellent selectivities have been obtained for the epoxidation of cyclohexene, cyclooctene, norbornene, cis-and trans-stilbene.
Monatsh Chem, 1992
The acid-base properties of the g-oxo bridged dimeric iron complexes [FeL]20 with the ligands based on S-alkyl-l,4-bis(substituted salicylidene)isothiosemicarbazide and a tetramer with Smethyl-1,4-bis(salicylidene)isothiosemicarbazide, {[FeL]20}213.I2, were investigated by cyclic voltammetry at glassy carbon electrode in DMF. Studies were carried out in the presence of either a weak (phenol) or a strong (HC104 aq.) acid. The stoichiometry of the reaction, changes in the general voltammetric pattern and the electrode reaction mechanism were discussed. These studies served as the basis for three-electrode amperometric titrations to determine the content of several of these complexes.
Ferrocene sulfonates as electrocatalysts for sulfide detection
Electrochimica Acta, 2006
The electrochemical characterization of both the mono- and di-substituted forms of ferrocene sulfonate are given. The results show both species produce voltammograms consistent with quasi-irreversible diffusion controlled redox reactions. The FcSO3− species was found to be easier to oxidize than its Fc(SO3)22− counterpart, due to the electron withdrawing affect of the sulfonate group on the Fe centre.In the presence of sulfide, the voltammetric response of FcSO3− is shown to be consistent with the occurrence of an electrocatalytic EC′ reaction. This analytical response was utilized as a means of determining sulfide and was found to be linear over the concentration 0.02–1 mM with a limit of detection of 14 μM.
Speciation of iron(II) and iron(III) using a dual electrode modified with electrocatalytic polymers
Analytical Chemistry, 1992
Speciation of metal ions has received considerable attention in diverse areas such as ecotoxicology,' geology,2 process analysis,3 and aquatic studies: Several approaches have been adopted for the speciation of Fe(I1) and Fe(II1). Electrochemical methods predominate in this type of but chromatographid' and spedrometrii?~' methods have also been described. For the chromatographic and the spectrometric methods, interconversion from one redox state to another? the use of different chelating agents? or the use of more than one detection system6 is required to differentiate between the two redox states. Polarographic methods appear almost universal in the electrochemical approach, but as the Fe-(II)/Fe(III) couple is reversible,'O the use of reagents to separate the half-wave potentials (Ell2) for the oxidation and reduction processes is necessary. Several reports concerning the determination of Fe(II) and Fe(III) at solid electrodes have also appeared."J2 However, the redox chemistry of the Fe-(II)/Fe(III) couple is poor at glassy carbon,ll and at platinum, electrode fouling is encountered.12