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Reorganizaciones estructurales ultrarrápidas en el estado excitado MLCT para el cobre (I) bis-fenantrolinas en
George B Shaw1, Christian D Grant, Hideaki Shirota
1Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
Journal of the American Chemical Society
|January 30, 2007
Resumen
Este estudio revela un aplanamiento estructural ultrarrápido en los complejos de cobre durante la fotoexcitación, independiente de los efectos del disolvente. Estos hallazgos son cruciales para la comprensión de la dinámica de estado excitado y el desarrollo de nuevos materiales de energía solar.
Área de la Ciencia:
- La fotoquímica es la fotoquímica.
- Coordinación Química de la Coordinación
- Ciencia de los materiales Ciencia de los materiales.
Sus antecedentes:
- Las transiciones de transferencia de carga de metal a ligando (MLCT) en los complejos de cobre implican cambios en la configuración electrónica y reordenamientos geométricos.
- Estudios anteriores indicaron el aplanamiento del estado de Franck-Condon y la ligadura con disolvente en el estado MLCT de [Cu(I) ((dmp) ((2))) ((+)).
Objetivo del estudio:
- Para investigar la dinámica estructural de estado excitado ultrarrápido de [Cu(I) ((dmp) ((2))) ((+)) y [Cu ((I) ((dpp)) ((2))) ((+)).
- Para aclarar los orígenes estructurales de los cambios espectroscópicos transitorios durante las transiciones MLCT.
- Comprender el papel de las propiedades del disolvente en la dinámica del estado excitado.
Principales métodos:
- Espectroscopia de absorción transitoria en disolventes con diferentes constantes dieléctricas, viscosidades y difusividades térmicas.
- Espectroscopia de conversión de fluorescencia hacia arriba para medir la dinámica de fluorescencia individual.
- Espectroscopia de absorción de rayos X de resolución temporal iniciada por láser (LITR-XAS) para conocimientos estructurales.
Principales resultados:
- Se observó relajación de la esfera interna independiente del disolvente a pesar de los movimientos geométricos de gran amplitud.
- Se identificó un proceso de aplanamiento ultrarrápido (77 fs) en el estado MLCT de [Cu{I}{dmp}{2}{+}.
- Las dinámicas de fluorescencia de singlet sugieren vías de desactivación rápida en la geometría de Franck-Condon.
Conclusiones:
- Un aplanamiento geométrico ultrarrápido inesperado ocurre en el estado MLCT de los complejos de cobre.
- La relajación de la esfera interna es un proceso dominante, en gran medida independiente de las interacciones del disolvente.
- Los hallazgos guían futuros estudios de rayos X ultrarrápidos y el diseño de complejos de cobre para aplicaciones de energía solar.
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