Transport and electron transfer dynamics in a polyether-tailed cobalt bipyridine molten salt: Electrolyte effects

Mary Elizabeth Williams; Leslie J. Lyons; Jeffrey W. Long; Royce W. Murray

doi:10.1021/jp971519t

Transport and electron transfer dynamics in a polyether-tailed cobalt bipyridine molten salt: Electrolyte effects

Mary Elizabeth Williams, Leslie J. Lyons, Jeffrey W. Long, Royce W. Murray

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32 Scopus citations

Abstract

Transport, ionic conductivity, and viscosity properties of the metal complex molten salt [Co(bpy(CO₂MePEG-350)₂)₃](ClO₄) ₂ (MePEG = monomethyl-terminated polyether, average MW = 350) are strongly affected by dissolution of LiClO₄ electrolyte in the melt. The physical self-diffusion of the [Co(bpy(CO₂MePEG-350)₂)₃]²⁺ and the rate of [Co(bpy(CO₂MePEG-350)₂)₃]^2+/+ electron self-exchange are slowed, the melt viscosity increased and ionic conductivity decreased, and thermal activation barriers for all are enhanced by increasing [LiClO₄]. Most of the effects are associated with the Li⁺ cation/polyether coordination well-known in polymer electrolytes, in which chain cross-linking and a decrease in chain segmental mobility occurs. The [Co(bpy(CO²MePEG-350)₂)₃]^2+/+ electron self-exchange reaction is shown to be adiabatic (kinetic prefactor ca. 10¹³ s^-1), and modest changes in its rate with [LiClO₄] are caused by changes in the electron transfer barrier energy. The results are used to draw a hierarchy of dynamics in the metal complex melt in which, for [LiClO₄] = 1.3 M, the average diffusive jump rate is ca. 3 s^-1, the average electron hopping rate is ca. 3 s^-1, and the rate of short-range motions of the hard metal complex core within its soft polyether shell (producing adjacent core - core contacts) is ca. ≥ 10⁵ s^-1.

Original language	English (US)
Pages (from-to)	7584-7591
Number of pages	8
Journal	Journal of Physical Chemistry B
Volume	101
Issue number	38
DOIs	https://doi.org/10.1021/jp971519t
State	Published - Sep 18 1997

All Science Journal Classification (ASJC) codes

Physical and Theoretical Chemistry
Surfaces, Coatings and Films
Materials Chemistry

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title = "Transport and electron transfer dynamics in a polyether-tailed cobalt bipyridine molten salt: Electrolyte effects",

abstract = "Transport, ionic conductivity, and viscosity properties of the metal complex molten salt [Co(bpy(CO2MePEG-350)2)3](ClO4) 2 (MePEG = monomethyl-terminated polyether, average MW = 350) are strongly affected by dissolution of LiClO4 electrolyte in the melt. The physical self-diffusion of the [Co(bpy(CO2MePEG-350)2)3]2+ and the rate of [Co(bpy(CO2MePEG-350)2)3]2+/+ electron self-exchange are slowed, the melt viscosity increased and ionic conductivity decreased, and thermal activation barriers for all are enhanced by increasing [LiClO4]. Most of the effects are associated with the Li+ cation/polyether coordination well-known in polymer electrolytes, in which chain cross-linking and a decrease in chain segmental mobility occurs. The [Co(bpy(CO2MePEG-350)2)3]2+/+ electron self-exchange reaction is shown to be adiabatic (kinetic prefactor ca. 1013 s-1), and modest changes in its rate with [LiClO4] are caused by changes in the electron transfer barrier energy. The results are used to draw a hierarchy of dynamics in the metal complex melt in which, for [LiClO4] = 1.3 M, the average diffusive jump rate is ca. 3 s-1, the average electron hopping rate is ca. 3 s-1, and the rate of short-range motions of the hard metal complex core within its soft polyether shell (producing adjacent core - core contacts) is ca. ≥ 105 s-1.",

author = "Williams, {Mary Elizabeth} and Lyons, {Leslie J.} and Long, {Jeffrey W.} and Murray, {Royce W.}",

year = "1997",

month = sep,

day = "18",

doi = "10.1021/jp971519t",

language = "English (US)",

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T1 - Transport and electron transfer dynamics in a polyether-tailed cobalt bipyridine molten salt

T2 - Electrolyte effects

AU - Williams, Mary Elizabeth

AU - Lyons, Leslie J.

AU - Long, Jeffrey W.

AU - Murray, Royce W.

PY - 1997/9/18

Y1 - 1997/9/18

N2 - Transport, ionic conductivity, and viscosity properties of the metal complex molten salt [Co(bpy(CO2MePEG-350)2)3](ClO4) 2 (MePEG = monomethyl-terminated polyether, average MW = 350) are strongly affected by dissolution of LiClO4 electrolyte in the melt. The physical self-diffusion of the [Co(bpy(CO2MePEG-350)2)3]2+ and the rate of [Co(bpy(CO2MePEG-350)2)3]2+/+ electron self-exchange are slowed, the melt viscosity increased and ionic conductivity decreased, and thermal activation barriers for all are enhanced by increasing [LiClO4]. Most of the effects are associated with the Li+ cation/polyether coordination well-known in polymer electrolytes, in which chain cross-linking and a decrease in chain segmental mobility occurs. The [Co(bpy(CO2MePEG-350)2)3]2+/+ electron self-exchange reaction is shown to be adiabatic (kinetic prefactor ca. 1013 s-1), and modest changes in its rate with [LiClO4] are caused by changes in the electron transfer barrier energy. The results are used to draw a hierarchy of dynamics in the metal complex melt in which, for [LiClO4] = 1.3 M, the average diffusive jump rate is ca. 3 s-1, the average electron hopping rate is ca. 3 s-1, and the rate of short-range motions of the hard metal complex core within its soft polyether shell (producing adjacent core - core contacts) is ca. ≥ 105 s-1.

AB - Transport, ionic conductivity, and viscosity properties of the metal complex molten salt [Co(bpy(CO2MePEG-350)2)3](ClO4) 2 (MePEG = monomethyl-terminated polyether, average MW = 350) are strongly affected by dissolution of LiClO4 electrolyte in the melt. The physical self-diffusion of the [Co(bpy(CO2MePEG-350)2)3]2+ and the rate of [Co(bpy(CO2MePEG-350)2)3]2+/+ electron self-exchange are slowed, the melt viscosity increased and ionic conductivity decreased, and thermal activation barriers for all are enhanced by increasing [LiClO4]. Most of the effects are associated with the Li+ cation/polyether coordination well-known in polymer electrolytes, in which chain cross-linking and a decrease in chain segmental mobility occurs. The [Co(bpy(CO2MePEG-350)2)3]2+/+ electron self-exchange reaction is shown to be adiabatic (kinetic prefactor ca. 1013 s-1), and modest changes in its rate with [LiClO4] are caused by changes in the electron transfer barrier energy. The results are used to draw a hierarchy of dynamics in the metal complex melt in which, for [LiClO4] = 1.3 M, the average diffusive jump rate is ca. 3 s-1, the average electron hopping rate is ca. 3 s-1, and the rate of short-range motions of the hard metal complex core within its soft polyether shell (producing adjacent core - core contacts) is ca. ≥ 105 s-1.

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Transport and electron transfer dynamics in a polyether-tailed cobalt bipyridine molten salt: Electrolyte effects

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