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Flexibilidad conformacional de los rotaxanos híbridos [3] y [4]

Selena J Lockyer¹, Selina Nawaz¹, Adam Brookfield¹

¹Department of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.

Journal of the American Chemical Society

|August 22, 2020

Resumen

Se sintetizaron y estudiaron nuevos complejos de rotaxano con anillos {Cr7Ni} y triángulos {CrNi2}. El [4]-rotaxano exhibe una estructura triangular, mientras que el [3]-rotaxano muestra un comportamiento de solución diferente en comparación con su forma cristalina.

Área de la Ciencia:

Química supramolecular
Química de coordinación
Ciencias de los materiales

Sus antecedentes:

Los rotaxanos son moléculas mecánicamente entrelazadas con aplicaciones potenciales en máquinas moleculares.
Los grupos heterometálicos ofrecen propiedades estructurales y electrónicas únicas.

Objetivo del estudio:

Sintetizar y caracterizar los nuevos complejos [4]- y [3]-rotaxano.
Investigar las propiedades estructurales y conformacionales de estos rotaxanos tanto en estado sólido como en solución.

Principales métodos:

Difracción de rayos X de un solo cristal para la determinación estructural.
Diseminación de rayos X de ángulo pequeño (SAXS) para el análisis de la estructura de la solución.
Simulaciones dinámicas moleculares atómicas para modelar el comportamiento conformacional.
Espectroscopia de resonancia paramagnética de electrones (EPR) para el estudio de estructuras en soluciones congeladas.

Principales resultados:

Síntesis y caracterización exitosas de [4]-rotaxano 3 y [3]-rotaxano 4.
La estructura cristalina de 3 muestra una disposición de triángulo isósceles, mientras que 4 tiene dos [2]-rotaxanos unidos al triángulo central.
Los estudios de solución revelan que 3 conserva su estructura cristalina, mientras que 4 adopta una conformación diferente.
Los estudios EPR indican que 4 forma moléculas más extendidas con una gama más amplia de conformaciones en soluciones congeladas en comparación con 3.

Conclusiones:

El estudio sintetizó y caracterizó con éxito nuevos complejos de rotaxano con intrincadas arquitecturas supramoleculares.
El comportamiento de la fase de solución difiere significativamente entre los [4]- y [3]-rotaxanos, destacando la influencia del diseño molecular en la flexibilidad conformacional.
Estos hallazgos contribuyen a la comprensión de las estructuras de rotaxano y sus propiedades dinámicas en diferentes entornos.

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