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Síntesis de la plantilla de lantánidos de los nudos de trébol de una sola mano
Gen Zhang1, Guzmán Gil-Ramírez1, Augustinas Markevicius1
1School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
Journal of the American Chemical Society
|July 28, 2015
Resumen
Los investigadores crearon nudos de trébol molecular quirales utilizando iones metálicos lantánidos y ligandos específicos. El proceso demostró una estereoselectividad completa, produciendo nudos con una sola mano, mostrando una química supramolecular avanzada.
Área de la Ciencia:
- Química supramolecular
- Síntesis orgánica
- Química de coordinación
Sus antecedentes:
- Los ligandos quirales y los iones metálicos son bloques de construcción para arquitecturas moleculares complejas.
- El control de la topología y la estereoquímica en ensamblajes moleculares sigue siendo un desafío significativo.
- Los iones lantánidos ofrecen propiedades de coordinación únicas para construir estructuras intrincadas.
Objetivo del estudio:
- Para sintetizar nudos de trébol molecular quiral topológicamente con una sola mano.
- Para investigar la formación estereoselectiva de estos nudos utilizando ligandos quirales de 2,6-piridindicarboxamida.
- Para capturar covalentemente la quiralidad helicoidal a través de la metátesis de olefinas de cierre de anillo.
Principales métodos:
- Ensamblaje de ligandos de 2,6-piridindicarboxamida alrededor de las plantillas de iones metálicos lantánidos.
- Metátesis de olefinas de cierre de anillo para formar enlaces covalentes y crear nudos de trébol.
- Caracterización mediante espectroscopia de RMN, espectrometría de masas y cristalografía de rayos X.
- Espectroscopia de dicroísmo circular para estudiar la expresión de la quiralidad topológica.
Principales resultados:
- Síntesis exitosa de complejos entrelazados 3:1 de ligando:lantanuro.
- Demostración de la estereoselectividad completa: el ligando (R,R) produjo nudos de trébol Λ, el ligando (S,S) produjo nudos de trébol Δ.
- Los ligandos racemicos dieron como resultado una mezcla estadística de complejos, lo que indica una falta de autoclasificación.
- La caracterización confirmó la formación de nudos de trébol y sus macrociclos de desnudos isoméricos.
Conclusiones:
- La captura covalente a través de la metástasis de olefinas crea efectivamente nudos de trébol topológicamente quirales.
- Los ligandos quirales dictan la manualidad de los nudos resultantes con alta estereoselectividad.
- Este trabajo proporciona un método robusto para sintetizar nudos moleculares enantiopuros.
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