Electrochemical characterization of iron porphyrin complexes in aprotic solvents

Constant, L.; Davis, Donald G.

doi:10.1021/ac60363a051

Cited by 67 publications

(35 citation statements)

References 48 publications

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“…This is in agreement with previous observations on porphyrin systems [74,76], including the hemepeptides [54].…”

Section: Factors Affecting the Stability Of Complexes Between Pyridinsupporting

confidence: 94%

The coordination of imidazole and substituted pyridines by the hemeoctapeptide N-acetyl-ferromicroperoxidase-8 (FeIINAcMP8)

Vashi

Marques

2004

Journal of Inorganic Biochemistry

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“…This is in agreement with previous observations on porphyrin systems [74,76], including the hemepeptides [54].…”

Section: Factors Affecting the Stability Of Complexes Between Pyridinsupporting

confidence: 94%

The coordination of imidazole and substituted pyridines by the hemeoctapeptide N-acetyl-ferromicroperoxidase-8 (FeIINAcMP8)

Vashi

Marques

2004

Journal of Inorganic Biochemistry

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“…Since the ability to bind molecular oxygen depends, at least in part, on the redox potential (18) this procedure permits the design of systems capable of reversibly binding oxygen. Whilst it seems that the redox potentials of iron porphyrins are less sensitive to the environment than those of iron phthalocyanine, dramatic changes can still be observed (23). Thus the 'tuning' mechanism may have a biological role through, for example, protein bound groups moving closer to, and further away from, the metal ion, with conformational change.…”

Section: Resultsmentioning

confidence: 99%

Redox potentials of metal phthalocyanines in non-aqueous media

Lever¹,

Wilshire²

1976

Can. J. Chem.

100

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A study of the redox potentials of a range of metal phthalocyanines in non-aqueous media compared with analogous data for some porphyrin complexes provides evidence for extensive back donation in metallophthalocyanines. The potentials for some couples are exceedingly sensitive to axial ligation. It is suggested that this sensitivity may be used to 'tune' a redox couple for a specific purpose such as designing a reversible oxygen breathing system.

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“…Although DMSO and DMF strongly solvate iron porphyrins (as judged by solubility characteristics), the iron porphyrins are considered to be closely associated with or bound to a counterion such as chloride or perchlorate (26). Iron porphyrins are not very (8). Thus in nonaqueous solutions using platinum electrodes, an iron porphyrin can be reduced in three oneelectron steps each of which is essentially reversible.…”

Section: Resultsmentioning

confidence: 99%

Surface electrochemistry of iron porphyrins and iron on tin oxide electrodes

Davis¹,

Murray²

1977

Anal. Chem.

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During an attempt to form amide linkages between lron porphyrlns and SnOz electrodes siianized with an ethylenediamine reagent, strong chemisorption of the porphyrin and of Fe( 111) on SnOz has been observed. ESCA and electrochemistry of the chemisorbed iron porphyrin Indicate approximate monolayer coverage. Chemisorbed iron porphyrin and Fe( ill) produce large waves at negative (-1.2 to -1.4 V vs. SCE) potentials in nonaqueous solvents which are interpreted as iron-catalyzed reduction of the SnOz electrode.Chemical modification of an electrode surface ( 1 ) refers to strong binding of a selected chemical reagent to the surface to endow it with some or all of the chemical and electrochemical properties of the selected reagent. An interesting example of chemisorption binding of allyl compounds to Pt electrodes has been reported (2). Modification based on covalent bond formation between reagent and electrode, a more permanent form of chemical derivitization of the electrode, has been of recent interest and has been described for carbon ( 3 , 4 ) , SnO2 ( 1 , 5 ) , and Ti02 (6) electrodes. The work on SnOz electrodes utilizes organosilane reagents, which can bear amine, pyridyl, and other functionalities useful for subsequent surface synthesis of immobilized electrochemically reactive centers (6). Since metalloporphyrins exhibit reversible and interesting electrochemistry in a variety of solvents (7-9), we have attempted to couple such compounds to SnO2 electrodes silanized with an amine reagent. Iron porphyrins were selected since they have been well studied (8 and references therein) and show catalytic properties for various reactions (10) including of course biological reactions (11 ). Expected redox chemistry of iron porphyrins was obtained using pyridine solvent but, as the project developed it became evident that substantial chemisorptive effects overlaid the coupling chemistry, and that some unusual and probably catalytic process produced sizable cathodic waves in nonaqueous solvents at potentials more negative than one volt (8). It would be expected iron(II1) porphyrins would be reduced to the iron(I1) state at about -0.2 V (7, 8). EXPERIMENTALApparatus and Cell. The SnOz electrodes are transparent, doped films on glass as used previously (1). Modified electrodes were prepared by reaction under mild, anhydrous conditions with 3-(2-aminoethy1amino)propyltrimethoxysilane to produce a surface with bonded layer of estimated (12) thickness of d = 4 A. Such electrodes bearing an ethylenediamine function are designated SnOz/en. Unreacted SnOz electrodes were also employed.A DuPont Model 650B spectrometer was used to obtain ESCA spectra as before ( I ) . Spectra of powder samples on sticky tape and of %-in. SnOn electrode disks are referenced to C Is contaminant taken a t 284.0 eV ( 1 3 ) . ESCA intensities are planimeter-measured band areas.Electrochemical experiments were carried out in a machinable ceramic cell similar to that used previously (1) and to that of Kuwana et al. (14). The area of the electrode expos...

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Electrochemical characterization of iron porphyrin complexes in aprotic solvents

Cited by 67 publications

References 48 publications

The coordination of imidazole and substituted pyridines by the hemeoctapeptide N-acetyl-ferromicroperoxidase-8 (FeIINAcMP8)

The coordination of imidazole and substituted pyridines by the hemeoctapeptide N-acetyl-ferromicroperoxidase-8 (FeIINAcMP8)

Redox potentials of metal phthalocyanines in non-aqueous media

Surface electrochemistry of iron porphyrins and iron on tin oxide electrodes

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