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Polimerizaciones topoquímicas monocristalinas a monocristalinas de un diacetileno terminal: dos transformaciones
Xi Ouyang1, Frank W Fowler, Joseph W Lauher
1Department of Chemistry, State University of New York, Stony Brook, New York 11794-3400, USA.
Journal of the American Chemical Society
|October 9, 2003
Resumen
La química anfitrión-invitado permitió la creación de un cocristal de triple hélice, lo que condujo a las primeras polimerizaciones estructuralmente caracterizadas de diacetilenos terminales con un aumento significativo de la densidad cristalina.
Área de la Ciencia:
- Se trata de una química supramolecular.
- Ingeniería de Cristal Ingeniería de Cristal.
- Química de los polímeros La química de los polímeros es la química de los polímeros.
Sus antecedentes:
- La química huésped-huésped ofrece un control preciso sobre el ensamblaje molecular.
- Los diacetilenos terminales son monómeros versátiles para la polimerización.
- La caracterización estructural es clave para comprender los mecanismos de reacción.
Objetivo del estudio:
- Para preparar y caracterizar estructuralmente los cocristales de un huésped de dipiridil oxalamida y un diacetileno terminal derivado del resorcinol.
- Para investigar la polimerización de las funcionalidades alineadas de diacetileno dentro de estos cocristales.
- Para analizar los cambios estructurales durante la polimerización y comparar diferentes vías de polimerización.
Principales métodos:
- Complejación anfitrión-invitado para formar cocristales.
- Cristalografía de rayos X para la determinación estructural de cocristales y polímeros.
- Análisis térmico para inducir la polimerización.
Principales resultados:
- Se formó una estructura de cocristal de triple hélice con unidades de diacetileno alineadas.
- La polimerización se produjo al calentar, dando el polímero correspondiente.
- Un hidrato cristalino también mostró una alineación adecuada de diacetileno y polimerizado a 50°C.
- Una oscilación sin precedentes de 2,4 Å hacia adentro del carbono C1 condujo a un aumento del 9% en la densidad cristalina.
- Esto representa las primeras polimerizaciones estructuralmente caracterizadas de diacetilenos terminales.
Conclusiones:
- La química anfitrión-invitado proporciona una ruta para controlar con precisión el arreglo de diacetileno para la polimerización.
- El mecanismo de polimerización observado, incluido el movimiento significativo de C1 y el aumento de densidad, ofrece nuevos conocimientos.
- Estos hallazgos allanan el camino para diseñar nuevos materiales con propiedades a medida a través de la polimerización controlada en estado sólido.
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