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Ciclociralidad dinámica y persistente en derivados enlazados con hidrógeno de triaminas de anillo medio
David T J Morris1, Steven M Wales1, Javier Echavarren1
1School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K.
Journal of the American Chemical Society
|August 18, 2023
Resumen
Las triureas cíclicas quirales exhiben cicloquiralidad dinámica, interconvirtiendo entre enantiómeros a través de la inversión de cuenco y la inversión de direccionalidad. Las modificaciones estructurales pueden controlar este proceso dinámico, lo que lleva a estructuras quirales estables.
Área de la Ciencia:
- Química supramolecular
- Síntesis orgánica
- Estereoquímica
Sus antecedentes:
- Los derivados del 1,4,7-triaciclonanano (TACN) son componentes clave en la química supramolecular.
- Comprender los procesos dinámicos en las moléculas quirales es crucial para diseñar nuevos materiales funcionales.
Objetivo del estudio:
- Síntesis y caracterización de nuevas triureas cíclicas derivadas del TACN.
- Investigar la naturaleza dinámica de la ciclociralidad y sus mecanismos subyacentes.
- Explorar modificaciones estructurales para el control de las barreras de enantiomerización.
Principales métodos:
- Síntesis de las triureas cíclicas.
- Cristalografía de rayos X para la determinación estructural.
- Espectroscopia de intercambio 1H NMR y 1H-1H a temperatura variable.
- Análisis de anillos y modelado computacional.
- Estudios en varios disolventes coordinadores y no coordinadores.
Principales resultados:
- Las triureas cíclicas quirales sintetizadas adoptan una conformación en forma de cuenco con una red de enlaces de hidrógeno cicloquirales.
- La ciclocirralidad es dinámica, con enantiomerización que ocurre a través de la inversión de cuenco y la reversión de direccionalidad (ΔG‡ = 63-71 kJ mol−1).
- Los disolventes de enlace con hidrógeno aumentan las tasas de enantiomerización.
- Las modificaciones estructurales (cancelación de trans- o cis- ciclohexano, sustitución por formamida) pueden inducir o inhibir la enantiomerización.
- Una estructura modificada logró una barrera de enantiomerización significativamente más alta (ΔG‡ = 93 kJ mol-1), lo que produjo un cuenco quiral estereocímicamente estable.
Conclusiones:
- Las triureas cíclicas exhiben ciclociralidad dinámica regida por interacciones de enlace de hidrógeno.
- La estabilidad estereoquímica puede controlarse con precisión mediante modificaciones estructurales específicas.
- Este trabajo proporciona una plataforma para diseñar arquitecturas supramoleculares estables y quirales.
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