Development of Novel Redox Systems by Use of Ligand Effect and Its Application to Potentiometry

Teshima, Norio; Katsumata, Hideyuki; Kawashima, Takuji

doi:10.2116/analsci.16.901

Cited by 13 publications

(10 citation statements)

References 52 publications

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“…The equilibrium constant of the redox reaction of Cu(II) with Fe(II) Cu 2+ + Fe 2+ Cu + + Fe 3+ (33) calculated from the standard redox potentials of Cu(II)/Cu(I) and Fe(III)/Fe(II) amounts 10 −10.5 [209]. The direct reaction between Cu(II) and Fe(II) is thus impossible.…”

Section: Fe and Cu Systemsmentioning

confidence: 99%

“…However, the equilibrium (Eq. (33)) can be shifted to the right in the presence of a ligand forming more stable complex with Fe(III) than with Fe(II) and of another ligand forming of more stable complex with Cu(I) than with Cu(II) [209]. Addition of an aminopolycarboxylate to solution containing the iron and copper compounds stabilizes strongly their higher oxidation states.…”

Section: Fe and Cu Systemsmentioning

confidence: 99%

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Homogeneous photocatalysis by transition metal complexes in the environment

Cieśla

Kocot

Mytych

et al. 2004

Journal of Molecular Catalysis A: Chemical

219

116

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Section: Fe and Cu Systemsmentioning

confidence: 99%

Section: Fe and Cu Systemsmentioning

confidence: 99%

Homogeneous photocatalysis by transition metal complexes in the environment

Cieśla

Kocot

Mytych

et al. 2004

Journal of Molecular Catalysis A: Chemical

219

116

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“…ET between Cu(II) and Fe(II) in H 2 O is thermodynamically nonspontaneous [26,27], and hence expectedly, we observed no significant potential break during potentiometric titration of Cu(II) with Fe(II). However, a marked change in potentiometric behavior in terms of a significant potential break in emf versus volume of titrant added was observed when the titration was carried out in the presence of NC (figure 1).…”

Section: Redox Titration Between Cu(ii) and Fe(ii)mentioning

confidence: 55%

Electroanalytical, kinetic, and mechanistic investigations of coordination-inspired electron transfer between Fe(II)/Cu(II)

Maqsood

Bhat

Khan

2013

Journal of Coordination Chemistry

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Herein, we report that the thermodynamic barrier for solution-phase electron transfer (ET) between Cu(II) and Fe(II) in aqueous acidic media can be overcome through the addition of 2,9-dimethyl-1,10-phenanthroline (Neocuproine [NC]) to the reaction mixture. A detailed discussion of the kinetic and mechanistic aspects of this coordination-inspired ET is presented. We attribute the observed change in the thermodynamic feasibility to the change in the reduction potential of Cu(II)-Cu(I) couple on its ligation with NC. The reaction was found to be slow, following firstorder kinetics with respect to each Cu(II) and Fe(II). In the presence of excess NC, the reaction was observed to proceed with a pseudo-second-order rate constant of 3.37 ± 0.05 dm 3 mol À1 s À1 at 298 K, with an activation barrier of ca. 26.22 kJ mol À1 . The slow reaction is attributed to the significant reorganization energy associated with large-scale changes in the coordination sphere of the oxidant. A two-step mechanism that explains the experimental observations is proposed for the investigated reaction. IntroductionCoordination complexes of transition metal ions [1-3] have established roles as metalloproteins in life processes. Analytical and other applications of coordination complexes make studies related to redox properties, mechanistic, kinetic, and applied aspects of inner and outer sphere electron transfers in coordination complexes important [4,5]. Few reports [6-8] using transition metal ion complexes as model systems for understanding electrontransfer processes in metalloproteins have been demonstrated. A long-standing challenge related to electron-transfer processes in metalloproteins is to unravel the basic cause for the metal ion center in electron transfer proteins that allows them to mediate a huge number of electron transfer reactions with high sensitivity and accuracy [9,10]. XRD and other structural studies in blue copper proteins have established that this ability of metalloproteins can be partly attributed to a large variation in the redox potential of metal ion center (190-780 mV) due to the nature and complexation geometry specific to the redox tuning properties of ligands [11,12].In continuation to our work on coordination-inspired redox systems [13,14], we investigated redox titration between Fe(II) and Cu(II) in the presence of 2,9-dimethyl-1,

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“…However, the valence numbers of the detection species can turn, because redox reactions between two metal ions can occur in the presence of a ligand, which changes the conditional redox potential of a M n+ /M (n-1)+ system. 19 In this case, cobalt(II) may reduce iron(III) to iron(II) 20 and vanadium(V) to vanadium(IV) 21 in the presence of phen. We determined the mobility, μep, of iron(II) and vanadium(V) by migrating a solution of Mohr's salt and a vanadium(V) standard solution, respectively.…”

Section: Resultsmentioning

confidence: 99%

An Alternative Interface for a Flow Injection-Capillary Electrophoresis System with Electrokinetic Injection

2007

Self Cite

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An alternative interface for flow injection-capillary electrophoresis based on electrokinetic injection is described. The interface basically consists of tubular platinum and a commercially available standard tee connector. The tubular platinum works as not only an electrode, but also a waste outlet of a split sample solution. The availability of the proposed interface is evaluated by the separation of several transition metals, such as vanadium, iron, and cobalt with 1,10-phenanthroline, and by the determination of iron in steel.

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Development of Novel Redox Systems by Use of Ligand Effect and Its Application to Potentiometry

Cited by 13 publications

References 52 publications

Homogeneous photocatalysis by transition metal complexes in the environment

Homogeneous photocatalysis by transition metal complexes in the environment

Electroanalytical, kinetic, and mechanistic investigations of coordination-inspired electron transfer between Fe(II)/Cu(II)

An Alternative Interface for a Flow Injection-Capillary Electrophoresis System with Electrokinetic Injection

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