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Aumentando el orden supramolecular 3D mediante la disminución del orden molecular. Un estudio comparativo de
Benjamin E Partridge, Pawaret Leowanawat, Emad Aqad
1‡Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6396, United States.
Journal of the American Chemical Society
|April 2, 2015
Resumen
Los investigadores desarrollaron nuevas moléculas de perileno bisimida tetraclorada (Cl4PBI) con dendrones, logrando un orden cristalino 3D mejorado en ensamblajes supramoleculares. Esto ofrece una nueva vía para estructuras cristalinas estables a temperaturas accesibles para el análisis y las aplicaciones.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Química supramolecular de las moléculas.
- Electrónica orgánica y electrónica orgánica.
Sus antecedentes:
- Las bisimidas de perileno (PBIs) son conocidas por formar estructuras supramoleculares ordenadas.
- Estudios previos sobre PBIs planas mostraron la formación dependiente de la temperatura de matrices 2D y 3D.
- La funcionalidad de los PBIs puede influir significativamente en su comportamiento de autoensamblaje.
Objetivo del estudio:
- Para investigar el ensamblaje supramolecular de derivados no planos y flexibles tetraclorados de PBI (Cl4PBI).
- Para comparar la autoorganización de Cl4PBI con dendrones hidrogenados y semifluorados con PBIs no clorados.
- Explorar nuevas rutas para lograr ensamblajes cristalinos estables a temperaturas accesibles.
Principales métodos:
- Síntesis de Cl4PBI funcionalizado con minidendros AB3 a través de diferentes longitudes de enlace (m = 0, 1, 2, 3) y un enlace de dióxido de etileno (m = 2EO).
- Caracterización de estructuras supramoleculares utilizando calorimetría de barrido diferencial (DSC), difracción de rayos X (XRD) y resonancia magnética nuclear de estado sólido (RMN).
- Análisis del autoensamblaje bajo control termodinámico y cinético.
Principales resultados:
- Cl4PBI con dendrones hidrogenados autoorganizados en matrices cristalinas exclusivamente 3D bajo control termodinámico (m = 0, 2), un resultado inesperado para bloques de construcción moleculares menos ordenados.
- Cl4PBI dendronizado semifluorado formó una matriz hexagonal columnar 2D (m = 3, control cinético) y una inusual fase hexagonal 2D parecida a un panal de abejas (m = 2EO, control termodinámico).
- Estos compuestos Cl4PBI permiten ensamblajes cristalinos estables a través del control termodinámico a temperaturas más bajas que las alcanzadas previamente con PBIs planas.
Conclusiones:
- La naturaleza no plana y flexible de Cl4PBI, combinada con la funcionalidad específica de los dendros, promueve un orden 3D más alto en los ensamblajes supramoleculares.
- El control termodinámico ofrece una estrategia viable para crear estructuras cristalinas 3D estables y ordenadas a partir de componentes moleculares menos ordenados.
- Estos hallazgos presentan una nueva vía para el diseño de materiales con autoensamblaje sintonizable para el análisis estructural y aplicaciones tecnológicas.
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