TY - JOUR
T1 - Electrochemistry of various substituted aminophenyl iron porphyrins. Part I. Redox properties of dissolved, adsorbed and electropolymerized species
AU - Bettelheim, A.
AU - Ozer, D.
AU - Harth, R.
AU - Murray, R. W.
N1 - Funding Information:
This researchw as supported by grant No. 85-00235f rom the United Binational Science Foundation (BSF), Jerusalem, Israel.
PY - 1989/7/10
Y1 - 1989/7/10
N2 - The redox properties of dissolved, adsorbed and electropolymerized films of iron(III) tetrakis(o-aminophenyl)porphyrin (Fe(III) (o-NH2)TPP), iron(III) tetrakis(p-aminophenyl)porphyrin (Fe(III) (p-NH2)TPP) and iron(III) tetrakis(p-N, N '-dimethylaminophenyl)porphyrin (Fe(III) (p-NMe2TPP) have been studied in aqueous solutions. Cyclic voltammetry at glassy carbon electrodes for the complexes dissolved in 1 M HCl showed two Fe(III)/Fe(II) waves with cathodic peak potentials of -0.14 and -0.38 V for Fe(o-NH2)TPP, -0.15 and -0.36 V for Fe(p-NH2)TPP, and -0.17 and -0.45 V for Fe(p-NMe2)TPP. Differential pulse voltammetry also revealed two reduction waves for Fe(o-NH2)TPP adsorbed on a glassy carbon electrode (-0.16 and +0.08 V) and only one reduction process for Fe(p-NH2)TPP (-0.24 V) and Fe(NMe2)TPP (-0.25 V). The reduction peak potentials for the polymeric films at pH 3.2 ±0.2 are -0.22 and +0.12 V for poly[Fe(o-NH2)TPP], -0.22 and -0.07 V for poly[Fe(p-NH2)TPP and -0.18 and -0.02 V for poly[Fe(p-NMe2)TPP]. Thin-layer spectroelectrochemical techniques for the dissolved iron porphyrins and cyclic voltammetry for the polymeric films in strong acidic solutions indicated irreversible changes resulting from a demetallation process occurring upon reduction. The demetallation rate for the Fe(II) (p-NMe2TPP compound (8×10-4 s-1) was about 20-fold smaller than that of the Fe(II) (p-NH2)TPP complex. In contrast, the polymeric films showed high stability at pH > 3: the cyclic voltammetric peak currents decreased by only 2% after 100 subsequent cycles in the potential range +0.4 to -0.8 V.
AB - The redox properties of dissolved, adsorbed and electropolymerized films of iron(III) tetrakis(o-aminophenyl)porphyrin (Fe(III) (o-NH2)TPP), iron(III) tetrakis(p-aminophenyl)porphyrin (Fe(III) (p-NH2)TPP) and iron(III) tetrakis(p-N, N '-dimethylaminophenyl)porphyrin (Fe(III) (p-NMe2TPP) have been studied in aqueous solutions. Cyclic voltammetry at glassy carbon electrodes for the complexes dissolved in 1 M HCl showed two Fe(III)/Fe(II) waves with cathodic peak potentials of -0.14 and -0.38 V for Fe(o-NH2)TPP, -0.15 and -0.36 V for Fe(p-NH2)TPP, and -0.17 and -0.45 V for Fe(p-NMe2)TPP. Differential pulse voltammetry also revealed two reduction waves for Fe(o-NH2)TPP adsorbed on a glassy carbon electrode (-0.16 and +0.08 V) and only one reduction process for Fe(p-NH2)TPP (-0.24 V) and Fe(NMe2)TPP (-0.25 V). The reduction peak potentials for the polymeric films at pH 3.2 ±0.2 are -0.22 and +0.12 V for poly[Fe(o-NH2)TPP], -0.22 and -0.07 V for poly[Fe(p-NH2)TPP and -0.18 and -0.02 V for poly[Fe(p-NMe2)TPP]. Thin-layer spectroelectrochemical techniques for the dissolved iron porphyrins and cyclic voltammetry for the polymeric films in strong acidic solutions indicated irreversible changes resulting from a demetallation process occurring upon reduction. The demetallation rate for the Fe(II) (p-NMe2TPP compound (8×10-4 s-1) was about 20-fold smaller than that of the Fe(II) (p-NH2)TPP complex. In contrast, the polymeric films showed high stability at pH > 3: the cyclic voltammetric peak currents decreased by only 2% after 100 subsequent cycles in the potential range +0.4 to -0.8 V.
UR - http://www.scopus.com/inward/record.url?scp=0011981374&partnerID=8YFLogxK
U2 - 10.1016/0022-0728(89)80218-9
DO - 10.1016/0022-0728(89)80218-9
M3 - Article
AN - SCOPUS:0011981374
SN - 0022-0728
VL - 266
SP - 93
EP - 108
JO - Journal of Electroanalytical Chemistry
JF - Journal of Electroanalytical Chemistry
IS - 1
ER -