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Origen molecular del efecto impar de las propiedades macroscópicas de las monocapas autoensambladas de alcanetiolato:
Fadwa Ben Amara1, Eric R Dionne1, Sahar Kassir1
1Département de chimie, FRQNT Quebec Centre for Advanced Materials, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC H3C 3J7, Canada.
Journal of the American Chemical Society
|June 30, 2020
Resumen
Este estudio revela cómo las monocapas orgánicas autoensambladas (SAM) en las superficies de oro cambian las propiedades en función de la longitud de la cadena y la paridad. Los efectos impares en SAM están relacionados con la orientación del grupo terminal, lo que afecta las características dieléctricas e hidrofóbicas.
Área de la Ciencia:
- Ciencias de los materiales
- Química de las superficies
- Nanotecnología
Sus antecedentes:
- Comprender las propiedades macroscópicas de las monocapas orgánicas autoensambladas (SAM) en superficies metálicas es crucial pero desafiante.
- Distinguir la interfaz frente a los efectos masivos en los SAM es clave para las aplicaciones.
Objetivo del estudio:
- Caracterizar los SAM prototipo de los n-alcanetiolatos en el oro.
- Para aclarar la influencia de la longitud de la cadena y la paridad en las propiedades de SAM.
- Para correlacionar la estructura molecular con el comportamiento macroscópico.
Principales métodos:
- Caracterización macroscópica mediante espectroscopia de impedancia electroquímica y goniometría de ángulo de contacto.
- Análisis a nivel molecular mediante espectroscopia de absorción por reflexión infrarroja.
- SAM investigados de n-alcanetiolatos en el oro (n=6-19).
Principales resultados:
- La capacidad SAM, la constante dieléctrica y la hidrofobidad dependen de la longitud de la cadena (n) y la paridad (par / impar).
- El aumento de la longitud de la cadena (n=6-16) mejora el orden conformacional.
- Las cadenas impares muestran más defectos; las cadenas pares exhiben una alternancia impar en la orientación del grupo metilo terminal.
Conclusiones:
- La longitud de la cadena influye en la constante dieléctrica y la hidrofobidad a través de cambios conformacionales en masa.
- Las variaciones impares en SAM se deben principalmente a la composición química de la interfaz y la orientación del grupo terminal.
- Los hallazgos ofrecen información sobre las relaciones estructura-propiedad para dieléctricos ultrafinos y uniones de túneles.
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