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Reactividad rápida de un cíclico nitrón-calix[4] pirrol conjugado con anión radical superóxido: estudios teóricos y

Shang-U Kim¹, Yangping Liu, Kevin M Nash

¹Department of Pharmacology and Center for Biomedical EPR Spectroscopy and Imaging, College of Medicine, The Ohio State University, Columbus, Ohio 43210, USA.

Journal of the American Chemical Society

|November 13, 2010

Resumen

Los investigadores desarrollaron CalixMPO, una nueva trampa de espín de nitrón, para detectar el anión radical superóxido (O2(•-)). Esta nueva sonda muestra una mayor reactividad y estabilidad, ofreciendo una mejor detección de esta especie reactiva clave de oxígeno.

Área de la Ciencia:

Biología Química Biología química.
Química supramolecular de las moléculas.
La espectroscopia es una técnica de espectroscopia.

Sus antecedentes:

Las trampas de espín de nitrógeno son cruciales para la identificación de radicales transitorios a través de la espectroscopia EPR.
El anión radical superóxido (O2(•-)) es un precursor de muchas especies reactivas de oxígeno.
Calix[4]pirroles exhiben una alta afinidad por los aniones.

Objetivo del estudio:

Diseñar, sintetizar y caracterizar un nuevo conjugado cíclico de nitrón de calix[4]pirrol (CalixMPO).
Evaluar CalixMPO como una trampa de espín para el anión radical superóxido (O2(•-)).
Investigar la reactividad y estabilidad de CalixMPO en la captura de O2

Principales métodos:

Estudios computacionales (PCM/B3LYP/6-31+G(d,p) para optimizar el diseño de CalixMPO.
1H espectroscopia de RMN para estudiar cambios conformacionales y propiedades electrónicas.
Espectroscopia UV-vis de flujo detenido y EPR para el análisis cinético de la formación y descomposición de aductos de O2

Principales resultados:

Los estudios computacionales predijeron un enlace de tipo colgante eficiente para el atrapamiento de espín de O2 ((•-) con entalpias de reacción favorables y energías libres.
CalixMPO exhibió cambios conformacionales dependientes del disolvente que influyen en sus propiedades electrónicas.
CalixMPO demostró robustos espectros de EPR para la captura de O2 , con una constante de velocidad de captura más alta y una vida media de adducto más larga en comparación con los nitrones convencionales.

Conclusiones:

CalixMPO representa una trampa de espín novedosa y efectiva para el anión radical superóxido (O2(•-)).
La mayor reactividad se atribuye a los efectos sinérgicos de la porción calix[4]pyrrole.
Este estudio destaca la primera aplicación de un receptor aniónico para la detección de O2 , un radical intermedio crítico.

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