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Energías de reorganización de transferencia de electrones de la esfera interna de las porfirinas de zinc
Xenia Amashukeli1, Nadine E Gruhn, Dennis L Lichtenberger
1Division of Chemistry and Chemical Engineering and the Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA.
Journal of the American Chemical Society
|November 26, 2004
Resumen
Las energías de reorganización de transferencia de electrones en las porfirinas de zinc se midieron utilizando espectroscopia de fotoelectrones. Los cambios estructurales durante la oxidación se producen principalmente dentro del anillo de la porfirina, sin ser influenciados significativamente por los sustituyentes o el medio ambiente.
Área de la Ciencia:
- Química Inorgánica La química inorgánica es la química inorgánica.
- Química Física es la química física.
- La espectroscopia es una técnica de espectroscopia.
Sus antecedentes:
- Los procesos de transferencia de electrones son fundamentales en química y biología.
- Comprender la energía de reorganización es crucial para predecir las tasas de transferencia de electrones.
- Las porfirinas de zinc son importantes en los sistemas biológicos y en la catálisis.
Objetivo del estudio:
- Determinar experimentalmente las energías de reorganización de la esfera interna para el Zn (protoporfirina IX) y el Zn (octaetilporfirina).
- Investigar la contribución de los cambios estructurales dentro del anillo de porfirina frente a los factores externos a la energía de reorganización.
- Evaluar la aplicabilidad de modelos computacionales para predecir estas energías.
Principales métodos:
- Se empleó la espectroscopia de fotoelectrones de valencia en fase gaseosa.
- El análisis de la forma de banda de la primera ionización se utilizó para determinar las energías de reorganización.
- Se realizó una comparación con varios modelos computacionales.
Principales resultados:
- Las energías totales de reorganización de la esfera interna experimentalmente determinadas para el autointercambio fueron de 120-140 meV.
- Los cambios estructurales durante la oxidación se limitan principalmente al anillo de la porfirina.
- Los sustitutos y los factores ambientales contribuyen mínimamente a la energía de reorganización.
Conclusiones:
- La estructura del anillo de porfirina dicta la contribución primaria a la energía de reorganización de la transferencia de electrones.
- La predicción computacional precisa de las bajas energías de reorganización requiere una cuidadosa selección de modelos.
- Los funcionales híbridos Hartree-Fock/DFT son prometedores para el modelado de estos sistemas.
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