Solvent gating of intramolecular electron transfer

Journal Article · Thu Feb 03 00:00:00 EST 1994 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100056a002· OSTI ID:5041774

Miller, R M ^[1]; Spears, K G; Gong, J H; Wach, M ^[2]

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1. California State Univ., Chico, CA (United States)
2. Northwestern Univ., Evanston, IL (United States)

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.

• DOE Contract Number: FG02-91ER14228
• OSTI ID: 5041774
• Journal Information: Journal of Physical Chemistry; (United States), Vol. 98:5; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

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