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Una jaula molecular basada en hidrocarburos de Chichibabin: el impacto de la rigidez estructural en la dinámica, la
Yong Ni1, Fernando Gordillo-Gámez2, Miriam Peña Alvarez3
1Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore.
Journal of the American Chemical Society
|June 27, 2020
Resumen
Una nueva jaula molecular, Ph14, exhibe una mayor estabilidad y propiedades electrónicas únicas debido a su estructura rígida. Esta jaula poliradicaloide encapsula selectivamente los fullerenos y sufre transformaciones estructurales bajo presión.
Área de la Ciencia:
- Química orgánica
- Ciencias de los materiales
- Química supramolecular
Sus antecedentes:
- El desarrollo de nuevas jaulas moleculares poliradicaloides conjugadas con π es crucial para los materiales avanzados.
- Comprender las relaciones estructura-propiedad en moléculas orgánicas complejas es un desafío continuo.
Objetivo del estudio:
- Para sintetizar y caracterizar una jaula molecular poliradicaloide tridimensional conjugada con π, Ph14.
- Investigar el impacto de su estructura rígida en la dinámica molecular, la estabilidad y las propiedades electrónicas en comparación con un análogo lineal.
- Explorar su potencial en la encapsulación molecular y las transformaciones inducidas por la presión.
Principales métodos:
- Síntesis de la jaula molecular Ph14 y su análogo lineal Ph4.
- Espectroscopia de resonancia magnética nuclear (RMN) de temperatura variable para determinar las barreras de energía de rotación.
- Espectroscopia Raman dependiente de la presión para el estudio de las transformaciones estructurales.
- Estudios de encapsulación de fullereno.
- Oxidación química y análisis cristalográfico de rayos X para determinar las estructuras de las especies catiónicas.
Principales resultados:
- Ph14 exhibe una barrera de energía de rotación más alta (15,64 kcal / mol) que Ph4 (11,40 kcal / mol), lo que conduce a una mejor estabilidad y una mayor brecha de energía singlet-triplete.
- La espectroscopia Raman dependiente de la presión reveló una transformación quinoidal a aromática en Ph14.
- Ph14 encapsulado selectivamente C70 sobre C60 con una constante de asociación alta (1.43 × 10 ^ 4 M ^ 1).
- Las especies catiónicas Ph14+ mostraron unidades bifenílicas coplanares, a diferencia de la conformación retorcida en Ph4+.
- Ph14 + formó estructuras columnares unidimensionales a través del apilamiento π-π.
Conclusiones:
- La estructura rígida y tridimensional del Ph14 mejora significativamente la estabilidad molecular e influye en las propiedades electrónicas.
- Ph14 demuestra potencial como material huésped para la encapsulación selectiva de fullereno.
- La jaula sufre transformaciones estructurales reversibles bajo presión, abriendo caminos para materiales sensibles.
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