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Comprensión y control de los procesos de transferencia de carga/electrones de corto y largo alcance en los conjugados
Ramandeep Kaur1, Fabio Possanza2, Francesca Limosani2
1Interdisciplinary Center for Molecular Materials, Department of Chemistry and Pharmacy, Friedrich-Alexander-University Erlangen-Nuremberg, Egerlandstrasse 3, 91058 Erlangen, Germany.
Journal of the American Chemical Society
|March 17, 2020
Resumen
Este estudio explora los conjugados multicomponentes de donante-donante-aceptor de electrones, revelando cómo los puentes moleculares controlan la separación y la recombinación de cargas. Los hallazgos destacan el papel de las propiedades de puente y la polaridad del disolvente en el logro de estados de carga separada de larga duración.
Área de la Ciencia:
- Química supramolecular
- La fotoquímica
- Ciencias de los materiales
Sus antecedentes:
- El desarrollo de sistemas fotosintéticos artificiales requiere una separación y transferencia de carga eficientes.
- Los conjugados multicomponentes ofrecen plataformas sintonizables para controlar la dinámica de los electrones.
- Comprender las vías de recombinación de carga es crucial para diseñar estados estables separados de carga.
Objetivo del estudio:
- Síntesis y caracterización de nuevos conjugados multicomponentes de donante-donante-aceptor de electrones.
- Investigar la influencia de los puentes moleculares en las dinámicas de separación y recombinación de cargas.
- Elucidar los mecanismos que rigen la formación de estados de carga separada de larga duración.
Principales métodos:
- Síntesis experimental y caracterización de los conjugados de zinc-porfirina (ZnP), ferroceno (Fc) y C60-fulereno.
- Espectroscopia de absorción transitorio de femto, pico, nano y microsegundo.
- Modelado computacional y análisis de longitud de onda múltiple/objetivo.
Principales resultados:
- Control demostrado de la transferencia de electrones y agujeros mediante puentes sintonizables fenileno-acetileno/acetileno.
- Confirmó la formación de dos estados de transferencia de carga adyacentes (C60-ZnP•−Fc•+ y C60•−ZnP•+-Fc) en el camino hacia un estado C60•−ZnP-Fc•+ distante.
- Estableció el papel crítico de las propiedades del puente molecular (energía de reorganización, factor de amortiguación) y la polaridad del disolvente en la determinación de los resultados de transferencia de carga y las constantes de velocidad.
Conclusiones:
- La naturaleza de alambre molecular de los puentes es decisiva para generar estados separados de carga distantes y de larga duración.
- La recombinación de cargas ocurre en diferentes regiones de la parábola de Marcus (invertida para estados adyacentes, normal para estados distantes).
- El ajuste de las propiedades del puente y la polaridad del disolvente permite la optimización de los procesos de transferencia de carga en sistemas artificiales.
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