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Foldameres a base de oligoindol con una conformación helicoidal inducida por el cloruro
Kyoung-Jin Chang1, Byung-Nam Kang, Min-Hee Lee
1Center for Bioactive Molecular Hybrids and Department of Chemistry, Yonsei University, Seoul 120-749, South Korea.
Journal of the American Chemical Society
|September 1, 2005
Resumen
Los nuevos pliegues de oligoindoles muestran plegamiento helicoidal en presencia de iones cloruro. Este plegamiento es impulsado por la unión de hidrógeno y se mejora al aumentar el número de unidades de indol, formando complejos estables 1:1.
Área de la Ciencia:
- Química supramolecular de las moléculas.
- Química orgánica es la química orgánica.
- La ciencia de los polímeros es la ciencia de los polímeros.
Sus antecedentes:
- Los foldameros son oligómeros sintéticos que imitan las estructuras secundarias de las proteínas.
- Los oligoindoles son una nueva clase de foldameros con aplicaciones potenciales en el reconocimiento molecular.
Objetivo del estudio:
- Para sintetizar y caracterizar los oligoindoles con un número variable de anillos de indoles (4, 6 y 8).
- Para investigar las propiedades de plegado de estos oligoindoles en presencia de iones de cloruro.
- Para dilucidar el mecanismo de unión y la estequiometría entre los oligoindoles y el cloruro.
Principales métodos:
- Síntesis de oligoindoles con 4, 6 y 8 unidades de indol.
- Espectroscopia de Resonancia Magnética Nuclear (1H NMR) para estudiar el enlace de hidrógeno y los cambios conformacionales.
- Espectroscopia de Efecto Overhauser de Marco Rotativo (ROESY) para confirmar el apilamiento helicoidal.
- Experimentos de titulación UV/visible para determinar las constantes de unión y estequiometría.
Principales resultados:
- Los oligoindoles exhibieron cambios de campo descendente en las señales de NH y cambios de campo ascendente en las señales aromáticas tras la adición de cloruro, lo que indica un enlace de hidrógeno y apilamiento de pi.
- Los experimentos de ROESY confirmaron la formación de estructuras helicoidales inducidas por el cloruro.
- Las titulaciones UV/visibles revelaron una formación compleja 1:1 entre oligoindoles y cloruro.
- Las constantes de asociación aumentaron con el número de grupos indoles NH, lo que sugiere una mayor afinidad de unión.
Conclusiones:
- Los oligoindoles adoptan una conformación helicoidal tras la complejación con los iones cloruro.
- El plegamiento helicoidal está mediado por las interacciones de enlaces de hidrógeno entre los grupos de indoles NH y cloruro.
- La afinidad de unión está directamente correlacionada con el número de unidades de indol, destacando su potencial como receptores de aniones.
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