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Enlaces de hidrógeno proporcionados e inconmensurados. enlaces de hidrógeno proporcionados e inconmensurados. Un
T L Nguyen1, F W Fowler, J W Lauher
1Department of Chemistry, State University of New York, Stony Brook, NY 11794, USA.
Journal of the American Chemical Society
|November 1, 2001
Resumen
Las ureas y las oxamidas suelen formar distintas redes de enlaces de hidrógeno. La cocristalización reveló que estas moléculas pueden formar nuevas redes beta 2D o conformaciones inusuales, alterando sus estructuras típicas.
Área de la Ciencia:
- Ingeniería de Cristal Ingeniería de Cristal.
- Química supramolecular de las moléculas.
- Ciencia de los materiales Ciencia de los materiales.
Sus antecedentes:
- Las ureas y las oxamidas comúnmente forman redes alfa 1D a través de enlaces de hidrógeno.
- Estas redes exhiben distancias de repetición características: aproximadamente 4,60 Å para las ureas y 5,05 Å para las oxamidas.
Objetivo del estudio:
- Investigar el comportamiento de cocristalización de la glicina urea y la glicina oxamida con derivados de la bipiridina.
- Determinar los resultados estructurales cuando las moléculas con distancias de red inconmensurables se ven obligadas a coexistir en el mismo cristal.
Principales métodos:
- Cocristalización de derivados de urea y oxamida con compuestos de bipiridina.
- Análisis por difracción de rayos X de los ocho cocristales resultantes.
Principales resultados:
- Los cocristales de toda-urea y toda-oxamida mantuvieron sus características redes alfa.
- Tres cocristales mezclados formaron redes beta 2D con subredes alternas de urea y oxamida, con un promedio de 4.87 Å.
- Un cristal mezclado mostró una red alfa de urea normal, mientras que la oxamida adoptó una conformación intramolecularmente unida al hidrógeno.
Conclusiones:
- La cocristalización puede conducir a la formación de nuevas redes beta 2D con distancias de repetición promediadas.
- En algunos casos, la formación de redes competidoras puede inducir conformaciones moleculares inusuales para maximizar las interacciones intramoleculares.
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