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Enlaces entrelazados mecánicamente dentro de estructuras orgánicas metálicas: efecto del tamaño del anillo en la
V Nicholas Vukotic1, Christopher A O'Keefe1, Kelong Zhu1
1Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada N9B 3P4.
Journal of the American Chemical Society
|July 16, 2015
Resumen
Los nuevos marcos metálico-orgánicos (MOF) incorporan moléculas mecánicamente entrelazadas (MIM) como enlaces. Estos MOF exhiben un comportamiento dinámico, con macrociclos de éter de corona que giran dentro de los poros del marco.
Área de la Ciencia:
- Ciencias de los materiales
- Química supramolecular
- La cristalografía
Sus antecedentes:
- Las estructuras metal-orgánicas (MOF) son materiales cristalinos construidos a partir de iones metálicos y enlaces orgánicos.
- Las moléculas mecánicamente entrelazadas (MIM) son compuestos con componentes mecánicamente unidos, como los rotaxanos.
- Las unidades de paddlewheel de cobre (II) son unidades de construcción secundarias comunes (SBU) en la síntesis de MOF.
Objetivo del estudio:
- Para sintetizar y caracterizar los MOF utilizando moléculas mecánicamente entrelazadas (MIM) como enlaces.
- Investigar las propiedades estructurales y dinámicas de los MOF que contienen macrociclos de éter de corona.
- Comprender la influencia del tamaño y la forma del macrociclo en la estructura del MOF y la movilidad del huésped.
Principales métodos:
- Se utilizó la cristalografía de rayos X para determinar las estructuras de los MOF sintetizados.
- Se empleó la espectroscopia de resonancia magnética nuclear (RMN) de estado sólido de temperatura variable 2H para estudiar el movimiento molecular.
- Síntesis de MOF utilizando SBUs de rueda de remo de cobre y enlaces de rotaxano con diferentes macrociclos de éter de corona.
Principales resultados:
- El estudio presenta MOF con enlaces rotaxanos lineales que forman estructuras de tipo nbo con macrociclos móviles.
- Un MOF sintetizado con un vinculante libre de macrociclos adoptó una nueva estructura de 12 bcc conectados.
- La RMN de temperatura variable reveló dinámicas de rotación distintas para diferentes tamaños de macrociclos dentro de los poros de MOF.
Conclusiones:
- La incorporación de MIM como enlaces en MOF permite la creación de marcos dinámicos con propiedades sintonizables.
- El tamaño y la forma del macrociclo influyen significativamente en la estructura MOF resultante y en la movilidad de los componentes entrelazados.
- Estos hallazgos abren vías para el diseño de materiales MOF receptivos y adaptables.
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