Electron self-exchange dynamics of an iron bipyridine complex redox polyether hybrid in its room temperature melt
- Univ. of North Carolina, Chapel Hill, NC (United States)
The derivatization of metal-tris(2,2`-bipyridine) complexes with oligo(ethylene glycol) tails produces ionically-conductive room-temperature melts in which appreciable concentrations of lithium electrolytes dissolve. Charge transport rates in these redox polyether hybrids, in the undiluted state, have been investigated using microelectrode solid state voltammetry. In the ligand bby(CO{sub 2}MPEG350){sub 2}, MPEG350 is -(CH{sub 2}CH{sub 2}O){sub 7}CH{sub 3}. The apparent diffusion coefficient, D{sub APP}, for the oxidation of [Fe(bpy(CO{sub 2}MPEG350){sub 2}){sub 3}](ClO{sub 4}){sub 2} is ca. 10{sup 3} larger than that for [CO(bpy(CO{sub 2}MPEG350){sub 2}){sub 3}](ClO{sub 4}){sub 2}. This difference is ascribed to transport dominated in the former by electron self-exchange reactions between adjacent Fe(II) and Fe(III) complexes. The very slow physical self-diffusivity in these metal complex melts, measured by the Co(III/II) reaction, provides an opportunity to assess the effect of electron donor/acceptor concentration on electron self-exchange dynamics in a semisolid matrix. Various models have been described for the site concentration dependency of charge transport in redox polymers, including ion association, electron migration, and percolation. This study examines the effects of changing redox site concentration on D{sub APP} by diluting [Fe(bpy(CO{sub 2}MPEG350){sub 2}){sub 3}](ClO{sub 4}){sub 2} isostructurally with the analogous Co and Ni complexes, and interprets the results in the context of the previous models. 31 refs., 6 figs.
- OSTI ID:
- 226686
- Journal Information:
- Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 13 Vol. 100; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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