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Transiciones de intervalencia (carga-resonancia) en sistemas orgánicos de valencia mixta. La transferencia de

D-L Sun¹, S V Rosokha, S V Lindeman

¹Department of Chemistry, University of Houston, Houston, Texas 77204-5003, USA.

Journal of the American Chemical Society

|December 18, 2003

Resumen

Los mecanismos de transferencia de electrones a través del espacio y a través del enlace son igualmente efectivos en sistemas de valencia mixta, independientemente de la separación del centro redox. Este hallazgo, confirmado por estudios experimentales y teóricos, avanza en la comprensión de la dinámica intramolecular de transferencia de electrones.

Área de la Ciencia:

Química Física es la química física.
La electrónica molecular es la electrónica molecular.
La espectroscopia es una técnica de espectroscopia.

Sus antecedentes:

Los sistemas de valencia mixta con centros redox aromáticos exhiben bandas de absorción de intervalencia en la región del infrarrojo cercano.
Los puentes moleculares, como el o-xileno y el p-fenileno, dictan la vía para la transferencia intramolecular de electrones (IET).
La comprensión de los mecanismos IET es crucial para el diseño de dispositivos electrónicos moleculares.

Objetivo del estudio:

Investigar y comparar las vías IET a través del espacio y a través del enlace en sistemas de valencia mixta.
Para determinar la eficacia relativa de estas vías a pesar de las diferentes distancias entre los centros redox.
Validar los hallazgos experimentales con cálculos teóricos basados en la teoría de Marcus-Hush.

Principales métodos:

Síntesis y caracterización de radicales catiónicos de valencia mixta con diferentes unidades puente.
Las sondas experimentales incluyen voltametría cíclica, cristalografía de rayos X, espectroscopia ESR y espectroscopia UV-Vis-NIR.
Cálculos teóricos de las constantes de velocidad de IET utilizando la teoría de Marcus-Hush y los elementos de acoplamiento electrónico derivados de las transiciones de intervalencia.

Principales resultados:

El puente de oxilileno facilita una vía IET a través del espacio a través de la movilidad conformacional y los centros redox cofaciales.
El puente de p-fenileno impone una vía IET de enlace a través debido a su estructura rígida y lineal.
Se descubrió que los mecanismos de espacio y de enlace eran igualmente efectivos para el IET, independientemente de la separación del centro redox.

Conclusiones:

Los mecanismos de transferencia de electrones a través del espacio y a través del enlace son comparables en eficiencia para IET.
Los resultados experimentales y teóricos muestran una fuerte coherencia, apoyando las vías propuestas de IET.
El estudio proporciona información fundamental sobre la dinámica de transferencia de electrones en sistemas moleculares complejos.

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