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Probando la estabilidad electrónica de aniones cargados múltiples: pireno sulfonado tri- y tetraniones
Xue-Bin Wang1, Alina P Sergeeva, Xiao-Peng Xing
1Department of Physics, Washington State University, 2710 University Drive, Richland, Washington 99354, USA.
Journal of the American Chemical Society
|June 26, 2009
Resumen
Los aniones de carga múltiple (AMC) exhiben estabilidad dinámica debido a la repulsión de Coulomb. Los investigadores estudiaron el metastable 1-hidroxi-3,6,8-pireno-trisulfonato (HPTS(3-)) y encontraron que su vida media era de 0,1 segundos.
Área de la Ciencia:
- Química Física es la química física.
- Física Química Física Química es la física de la química.
- La espectroscopia es una técnica de espectroscopia.
Sus antecedentes:
- Los aniones de carga múltiple (MCAs) poseen estabilidad dinámica debido a la fuerte repulsión intramolecular de Coulomb, lo que permite la observación de especies electrónicamente metastables.
- El 1-hidroxi-3,6,8-pireno-trisulfonato (HPTS(3-)) fue previamente identificado como un MCA metastable de larga vida con una energía negativa de unión de electrones de -0.66 eV.
Objetivo del estudio:
- Para investigar la desintegración espontánea y determinar la vida media de la HPTS metastable(3-) utilizando la espectrometría de masas de trampa de Penning.
- Explorar los límites de la metestabilidad electrónica tratando de sintetizar y caracterizar el pireno-1,3,6,8-tetrasulfonato relacionado cargado cuatro veces ([Py(SO(3)) (((4)) ((4-)).
Principales métodos:
- Se empleó la espectrometría de masas de trampa de Penning para monitorear la desintegración de HPTS(3-) en HPTS(*2-) y un electrón.
- Se utilizó la espectroscopia de fotoelectrones para determinar las energías de unión de electrones de las especies sintetizadas con carga triple.
- Se realizaron cálculos ab initio para predecir la energía de unión de electrones del anión cargado cuatro veces.
Principales resultados:
- La vida media de HPTS(3-) se determinó experimentalmente en 0,1 segundos.
- No se observó el anión de carga cuádruple [Py (((SO ((3)) ((4))) ((4-)); en su lugar, se detectaron sus productos de desintegración, incluido el anión radical de carga triple [Py (((SO ((3)) ((4))) ((*3-)) y los pares de iones.
- Se midieron las energías de unión de electrones: +0.5 eV para [Py(SO((3))(4)](*3-), 0.0 eV para [Py(SO(3))(4)H](3-), y -0.1 eV para [Py(SO(3))(4)Na](3-).
- Los cálculos ab initio predijeron una energía de unión de electrones altamente negativa de -2.78 eV para [Py(SO(3)) ((4)) ((4-).
Conclusiones:
- El estudio confirma la estabilidad dinámica de los MCAs y cuantifica la metestabilidad de los HPTS.
- La extrema repulsión intramolecular de Coulomb en [Py(SO(3))(4)](4-) hace que sea extremadamente efímera, consistente con las predicciones teóricas.
- Los hallazgos proporcionan información sobre los factores que rigen la metestabilidad electrónica en aniones de carga múltiple.
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