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Interacción del estado de carga, labilidad y magnetismo en el cúmulo de moléculas Au25(SR) 18 parecidas a moléculas
Sabrina Antonello1, Neranjan V Perera, Marco Ruzzi
1Department of Chemistry, University of Padova , via Marzolo 1, 35131 Padova, Italy.
Journal of the American Chemical Society
|October 4, 2013
Resumen
Este estudio aclara las propiedades electroquímicas y magnéticas de los nanocúmulos de oro Au25(SR)18.18. Los nuevos hallazgos contradicen la literatura reciente, proporcionando una comprensión consistente de su comportamiento a través de diferentes estados de carga.
Área de la Ciencia:
- Nanomateriales Química de los nanomateriales
- La electroquímica es electroquímica.
- La espectroscopia es una técnica de espectroscopia.
- Química computacional es la química computacional.
Sus antecedentes:
- Los nanocúmulos de oro similares a moléculas, como Au25(SR)18, exhiben propiedades electroquímicas y ópticas únicas.
- La literatura reciente presenta descripciones contradictorias de las propiedades del Au25 ((SR) 18), lo que requiere una mayor investigación.
- Comprender el comportamiento dependiente del estado de carga es crucial para su aplicación.
Objetivo del estudio:
- Aclarar la cinética electroquímica y las energías de reorganización de la reducción y oxidación de Au25(SR)18.
- Para investigar las propiedades magnéticas de Au25(SR)18 en estados neutros y oxidados.
- Para conciliar los hallazgos experimentales con las predicciones teóricas sobre la estructura electrónica y el magnetismo.
Principales métodos:
- Monodispersión Au25 (((SR) 18 ((0) por síntesis.
- Voltametría cíclica bajo condiciones controladas para determinar la cinética de transferencia de electrones y las energías de reorganización.
- Espectroscopia de resonancia paramagnética de electrones de onda continua (cw-EPR) para estudiar el magnetismo.
- Computaciones de la Teoría Funcional de Densidad (DFT) para espectros de absorción óptica y estructura electrónica.
Principales resultados:
- Constantes establecidas de velocidad de transferencia de electrones y energías de reorganización para los procesos redox Au25(SR) 18.
- Irreversibilidad química demostrada para la reducción a Au25 (((SR) 18 ((2-) y la oxidación a Au25 ((SR) 18 ((2+) / Au25 ((SR) 18 ((3+).
- Proporcionó evidencia convincente de que el Au25 ((SR) 18 ((+) es diamagnético, lo que contradice los informes recientes.
- Los cálculos de DFT reproducen con precisión los espectros ópticos experimentales y las variaciones de la brecha de energía con el estado de carga.
- Se reveló una división significativa de los niveles de HOMO en las especies catiónicas, lo que limita la aplicabilidad del modelo superatómico.
Conclusiones:
- El estudio proporciona una imagen autoconsistente de las propiedades de Au25(SR)18 en función del estado de carga.
- Los hallazgos desafían las interpretaciones recientes del comportamiento redox y magnético del Au25 ((SR) 18).
- La metodología ofrece un plan para comprender nanocúmulos de oro similares a moléculas similares.
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