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La captura de espín del estado excitado inducida por la luz en sistemas de cruce de espín basados en tetrazol
Belén Ordejón1, Coen de Graaf, Carmen Sousa
1Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel-lí Domingo s/n, 43007 Tarragona, Spain.
Journal of the American Chemical Society
|September 25, 2008
Resumen
Los cálculos ab initio revelan cómo los estados electrónicos en los complejos de hierro cambian con la distancia Fe-ligand, explicando los mecanismos de atrapamiento de espín de estado excitado inducido por la luz (LIESST). El estudio detalla las conversiones de espín cruciales para la comprensión de estos fenómenos en los sistemas de metales de transición.
Área de la Ciencia:
- Química computacional es la química computacional.
- Ciencia de los materiales Ciencia de los materiales.
- La mecánica cuántica es la mecánica cuántica.
Sus antecedentes:
- El atrapamiento de espín de estado excitado inducido por la luz (LIESST) es un fenómeno observado en complejos de metales de transición.
- Comprender las variaciones de estado electrónico y las conversiones de giro es clave para controlar la dinámica de LIESST.
Objetivo del estudio:
- Investigar las variaciones de energía de los estados electrónicos relevantes para LIESST en complejos Fe (II) como función de la distancia Fe-ligando.
- Para dilucidar los mecanismos de la desactivación del singlete excitado y revertir LIESST.
- Para explorar la influencia del metal de transición en el mecanismo LIESST.
Principales métodos:
- Se realizaron cálculos ab initio en los complejos Fe(II) con los ligandos 1-H-tetrazol (tz).
- Las energías de estado electrónico se analizaron como una función de la distancia Fe-ligando.
- Los cálculos se extendieron a los complejos Co (II), Co (III) y Fe (III) para estudiar la influencia del metal de transición.
Principales resultados:
- Los cálculos reproducen con precisión las distancias de equilibrio y las energías de absorción para los complejos Fe (II).
- Caminos de desactivación propuestos para estados singlet excitados que implican cruce intersistémico (ISC) a estados triplet y quintet.
- Identificó el ISC de quinteto-triplete y triplete-singlete como pasos clave en el LIESST inverso.
- Se observaron fuertes similitudes entre los sistemas Fe ((II) y Fe ((III), lo que sugiere un mecanismo LIESST conservado.
Conclusiones:
- El estudio proporciona información detallada sobre la estructura electrónica y la dinámica de espín que rigen LIESST en Fe (II) y los complejos de metales de transición relacionados.
- Los hallazgos sugieren que las conversiones electrónicas fundamentales que impulsan LIESST se conservan a través de diferentes estados de oxidación del hierro y en complejos de cobalto.
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