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Separación de carga de ruptura de simetría ultrarrápida y reparto de electrones en triángulos moleculares de

Yilei Wu, Ryan M Young, Marco Frasconi

¹Institut für Organische Chemie and Center for Nanosystems Chemistry, Universität Würzburg , Am Hubland, 97074 Würzburg, Germany.

Journal of the American Chemical Society

|September 30, 2015

Resumen

Desarrollamos un triángulo molecular quiral utilizando unidades de diimida de perileno (PDI). Esta estructura permite la separación ultra rápida de la carga y el intercambio de electrones, evitando la formación de excimer para una absorción de luz eficiente.

Área de la Ciencia:

Química orgánica
La fotoquímica
Ciencias de los materiales

Sus antecedentes:

Las diimidas de perileno (PDIs) son conocidas por sus fuertes propiedades de absorción de luz y aceptación de electrones.
El control de las interacciones intermoleculares en los agregados PDI es crucial para optimizar las aplicaciones optoelectrónicas.
El diseño molecular puede influir en la dinámica de estado excitado y la eficiencia de separación de carga.

Objetivo del estudio:

Sintetizar y caracterizar un nuevo triángulo molecular quiral compuesto por tres unidades PDI vinculadas covalentemente.
Para investigar la dinámica de estado excitado y los mecanismos de separación de carga en esta arquitectura triangular PDI.
Explorar el potencial para la deslocalización controlada de electrones y el transporte de carga.

Principales métodos:

Síntesis de un triángulo molecular PDI quiral.
Espectroscopia de absorción transitorio de femtosegundos para estudiar la separación de carga ultrarrápida.
Espectroscopia de resonancia paramagnética de electrones (EPR) y resonancia doble electrón-nuclear (ENDOR) para sondear la deslocalización de electrones.

Principales resultados:

La arquitectura triangular rígida minimiza el acoplamiento electrónico entre las unidades PDI, favoreciendo la separación de cargas sobre la formación de excimer.
Se observó una separación de carga de ruptura de simetría ultrarrápida con un tiempo característico (τCS) de 12,0 ± 0,2 ps.
La espectroscopia de resonancia paramagnética de electrones / resonancia nuclear doble confirmó el intercambio completo de electrones entre los tres PDIs después de la reducción, lo que indica aniones radicales deslocalizados.
La recombinación de la carga se produjo rápidamente (τCR = 1,12 ± 0,01 ns) sin la formación de estados excitados triplet.

Conclusiones:

El triángulo quiral PDI separa efectivamente la carga tras la fotoexcitación debido a su estructura rígida.
La molécula exhibe una deslocalización eficiente de electrones, lo que lleva a un estado aniónico radical compartido.
Este trabajo demuestra un diseño molecular prometedor para controlar la dinámica de carga en materiales que absorben la luz.

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