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Coexistencia de morfologías helicoidales en pilas columnares de hidrazonas discóticas en forma de estrella
Jie Shu1, Dmytro Dudenko, Morteza Esmaeili
1Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
Journal of the American Chemical Society
|July 9, 2013
Resumen
Las moléculas de hidrazona discótica forman fases cristalinas líquidas (LC) con una organización columnar hexagonal. Las fases cristalinas complejas revelan morfologías de apilamiento helicoidal, influenciadas por la longitud de la cadena alkoxi, lo que sugiere el potencial de la electrónica orgánica.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Química orgánica es la química orgánica.
- La cristalografía es una técnica de cristalografía.
Sus antecedentes:
- Las moléculas de hidrazona discótica exhiben fases cristalinas líquidas (LC) discóticas únicas debido a los enlaces de hidrógeno intramoleculares.
- Estas moléculas poseen núcleos rígidos y cadenas alcóxicas periféricas flexibles, lo que influye en su autoensamblaje y comportamiento de fase.
Objetivo del estudio:
- Investigar el comportamiento termotrópico y la organización en estado sólido de los derivados discoticos de hidrazona con diferentes longitudes de cadenas alkoxi (seis, ocho y diez carbonos).
- Para dilucidar las morfologías de embalaje y apilamiento molecular tanto en la fase cristalina líquida como en la cristalina.
Principales métodos:
- Diseminación bidimensional de rayos X de gran angular (2DWAXS) para la identificación de fase y el análisis estructural.
- Dispersión de rayos X de gran angular (WAXS) y resonancia magnética nuclear avanzada en estado sólido (SSNMR) para la determinación detallada de la estructura en estado sólido.
- Ab initio cálculos para apoyar el modelado estructural y el análisis.
Principales resultados:
- Los tres compuestos exhibieron fases cristalinas líquidas columnares hexagonales (Colh) con discos no inclinados a temperaturas elevadas.
- Se observaron fases cristalinas complejas a 25 °C para compuestos con seis y diez cadenas alcoxi de carbono, con columnas rígidas y cadenas laterales flexibles.
- Se modelaron morfologías de apilamiento de columnas helicoidales coexistentes con ángulos de inclinación / inclinación distintos, lo que muestra la dependencia de la longitud de la cadena alkoxi.
Conclusiones:
- La longitud de las cadenas laterales alcoxi influye significativamente en el embalaje y los ángulos de inclinación en las fases columnares cristalinas.
- Las morfologías complejas de empaque observadas en cristales líquidos columnares son raras y destacan el potencial de estructuras intrincadas en sistemas orgánicos similares.
- Estos hallazgos sugieren la utilidad de los derivados de hidrazona discótica como materiales potenciales para aplicaciones electrónicas orgánicas.
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