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Article
Parallel variation of mass transport and heterogeneous and homogeneous electron transfer rates in hybrid redox polyether molten salts
Journal of Physical Chemistry B
  • Amanda S Harper-Leatherman, Fairfield University
  • Dongil Lee
  • Joseph C. Crooker
  • Wei Wang
  • Mary E. Williams
  • Royce W. Murray
Document Type
Article
Article Version
Publisher's PDF
Publication Date
1-1-2004
Abstract

Metal complexes can be prepared as highly viscous (semisolid), room temperature molten salts by combining them with oligomeric polyether substituents. The fluidity and transport properties of these hybrid redox polyether melts can be systematically manipulated by changing the oligomeric chain lengths and by adding unattached oligomers as plasticizers. This paper describes the voltammetrically measured transport properties of several Co(II) polypyridine (2,2‘-bipyridine, phenanthroline) melts. The properties evaluated are the physical self-diffusion coefficient (DPHYS) of the cationic complex in its melt, the diffusivity of its counterion (DCION), the heterogeneous electron-transfer rate constant (kHET) of the Co(III/II) oxidation at the electrode surface, and the rate constant (kEX) for homogeneous electron self-exchange between Co(II) and Co(I) in the mixed valent layer next to the electrode. These dynamics parameters change in parallel manners, over a large (>103) range of values, when the melt fluidity is changed by plasticizers or temperature. While kHET and kEX both change systematically with DPHYS, they change on a more nearly proportional basis with DCION. The latter relationship is interpreted as a kind of solvent dynamics control in which both the homogeneous Co(II/I) and heterogeneous Co(III/II) reaction rates are controlled by the ionic atmosphere relaxation time constant, namely, the time constant of redistribution of counterions following an electron-transfer step that has produced a nonequilibrium charge distribution. DCION provides a measure of the ion atmosphere relaxation rate.

Comments

Copyright 2004 American Chemical Society

The published article is also available on the journal site:

http://pubs.acs.org/doi/abs/10.1021/jp036479%2B

Published Citation
Harper, Amanda S.; Lee, Dongil; Crooker, Joseph C.; Wang, Wei; Williams, Mary E.; Murray, Royce W. “Parallel variation of mass transport and heterogeneous and homogeneous electron transfer rates in hybrid redox polyether molten salts.” Journal of Physical Chemistry B, 2004, 108 (6), 1866-1873.
DOI
10.1021/jp036479+
None
Peer Reviewed
Citation Information
Amanda S Harper-Leatherman, Dongil Lee, Joseph C. Crooker, Wei Wang, et al.. "Parallel variation of mass transport and heterogeneous and homogeneous electron transfer rates in hybrid redox polyether molten salts" Journal of Physical Chemistry B Vol. 108 Iss. 6 (2004)
Available at: http://works.bepress.com/amanda_harper-leatherman/6/