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Transición polimórfica bifurcada y fluorescencia termocrómica de un cristal molecular que involucra la rotación
Yun-Hsuan Yang1, Yu-Shan Chen1, Wei-Tsung Chuang2
1Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.
Journal of the American Chemical Society
|March 12, 2024
Resumen
Una nueva red de engranajes moleculares 3D en un cristal de emisión verde permite transiciones polimórficas. Este sistema transmite eficientemente la energía térmica, impulsando cambios en el movimiento molecular y la estructura cristalina, lo que lleva a nuevas propiedades emisoras.
Área de la Ciencia:
- Química del estado sólido
- La cristalografía
- Ciencias de los materiales
Sus antecedentes:
- El movimiento molecular en los sólidos impulsa las transiciones polimórficas y los comportamientos sensibles a los estímulos.
- Comprender el vínculo entre la estructura cristalina y la movilidad molecular es crucial pero desafiante.
Objetivo del estudio:
- Investigar cómo una red de engranajes supramoleculares 3D influye en las transiciones polimórficas y el movimiento molecular.
- Elucidar el mecanismo de las transiciones polimórficas bifurcadas inducidas térmicamente y el fluorocromismo.
Principales métodos:
- Síntesis y caracterización de un sistema π antraceno-pentiptceno sustituido por dialquilamino.
- Cristalografía de rayos X para analizar las estructuras cristalinas y los arreglos supramoleculares.
- Estudios a temperatura variable (170-235 °C) para observar las transiciones polimórficas y los estados intermedios.
- Análisis espectroscópico para controlar los cambios en las propiedades de emisión (fluorocromismo).
Principales resultados:
- Una red de engranajes supramoleculares 3D en polimorfismo 1G facilita la rotación supramolecular 3D correlacionada.
- Esta rotación induce cambios conformacionales, constriñe las columnas supramoleculares y desactiva la red de engranajes, formando un estado intermedio.
- Las transiciones bifurcadas e irreversibles a emisiones amarillas 1Y y emisiones verdes 1G* ocurren a través de la rotación hacia adelante o hacia atrás.
- 1G* carece de enganche de engranajes, lo que impide una mayor transformación, mientras que 1G se puede restaurar desde 1Y o 1G* mediante molienda o vapor DCM.
Conclusiones:
- Demuestra una correlación directa entre la estructura cristalina, específicamente un sistema de engranajes moleculares en 3D, y el movimiento molecular en estado sólido.
- Destaca la transmisión eficiente de energía térmica a través de la red de engranajes para impulsar las transiciones polimórficas y el fluorocromismo.
- Presenta un nuevo mecanismo para controlar las propiedades del estado sólido a través de arquitecturas supramoleculares diseñadas y movimiento molecular cooperativo.
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