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Title: Solvent gating of intramolecular electron transfer

Abstract

The rates for ionic photodissociation of malachite green leucocyanide to form cyanide ion and a malachite green carbonium ion were measured as a function of solvent and temperature. The observed rates in mixtures of polar and nonpolar solvents all had an activation energy of about 1 kcal/mol for a wide range of dielectric constants. This dissociative intramolecular electron transfer (DIET) is unusual because it is the first example where solvent configurational entropy changes are required to enable a large amplitude molecular distortion leading to a nonadiabatic electron transfer and ionic dissociation. This solvent gated intramolecular electron-transfer mechanism is supported by analysis of the preexponential and activation energy trends in dipolar aprotic solven mixtures and alcohol solvents. The large amplitude motion is not separately measurable due to the slow gating rates, but viscosity effects on both the preexponential and the activation energy are analyzed to demonstrate consistency with a barrierless diffusion model having a structural dependence on electron-transfer rate. The rate has an inverse dependence on viscosity raised to the 0.53 power. 36 refs., 6 figs., 4 tabs.

Authors:
 [1]; ; ;  [2]
  1. California State Univ., Chico, CA (United States)
  2. Northwestern Univ., Evanston, IL (United States)
Publication Date:
OSTI Identifier:
5041774
DOE Contract Number:  
FG02-91ER14228
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry; (United States)
Additional Journal Information:
Journal Volume: 98:5; Journal ID: ISSN 0022-3654
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CHEMICAL REACTION KINETICS; TEMPERATURE DEPENDENCE; ORGANIC COMPOUNDS; PHOTOLYSIS; ALCOHOLS; CHEMICAL ACTIVATION; COMPILED DATA; DIFFUSION; ELECTRON TRANSFER; ENTROPY; SOLVENTS; VISCOSITY; CHEMICAL REACTIONS; DATA; DECOMPOSITION; HYDROXY COMPOUNDS; INFORMATION; KINETICS; NUMERICAL DATA; PHOTOCHEMICAL REACTIONS; PHYSICAL PROPERTIES; REACTION KINETICS; THERMODYNAMIC PROPERTIES; 400201* - Chemical & Physicochemical Properties; 400500 - Photochemistry

Citation Formats

Miller, R M, Spears, K G, Gong, J H, and Wach, M. Solvent gating of intramolecular electron transfer. United States: N. p., 1994. Web. doi:10.1021/j100056a002.
Miller, R M, Spears, K G, Gong, J H, & Wach, M. Solvent gating of intramolecular electron transfer. United States. https://doi.org/10.1021/j100056a002
Miller, R M, Spears, K G, Gong, J H, and Wach, M. 1994. "Solvent gating of intramolecular electron transfer". United States. https://doi.org/10.1021/j100056a002.
@article{osti_5041774,
title = {Solvent gating of intramolecular electron transfer},
author = {Miller, R M and Spears, K G and Gong, J H and Wach, M},
abstractNote = {The rates for ionic photodissociation of malachite green leucocyanide to form cyanide ion and a malachite green carbonium ion were measured as a function of solvent and temperature. The observed rates in mixtures of polar and nonpolar solvents all had an activation energy of about 1 kcal/mol for a wide range of dielectric constants. This dissociative intramolecular electron transfer (DIET) is unusual because it is the first example where solvent configurational entropy changes are required to enable a large amplitude molecular distortion leading to a nonadiabatic electron transfer and ionic dissociation. This solvent gated intramolecular electron-transfer mechanism is supported by analysis of the preexponential and activation energy trends in dipolar aprotic solven mixtures and alcohol solvents. The large amplitude motion is not separately measurable due to the slow gating rates, but viscosity effects on both the preexponential and the activation energy are analyzed to demonstrate consistency with a barrierless diffusion model having a structural dependence on electron-transfer rate. The rate has an inverse dependence on viscosity raised to the 0.53 power. 36 refs., 6 figs., 4 tabs.},
doi = {10.1021/j100056a002},
url = {https://www.osti.gov/biblio/5041774}, journal = {Journal of Physical Chemistry; (United States)},
issn = {0022-3654},
number = ,
volume = 98:5,
place = {United States},
year = {Thu Feb 03 00:00:00 EST 1994},
month = {Thu Feb 03 00:00:00 EST 1994}
}