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De las triazinas a las heptazinas: descifrando la estructura local de materiales amorfos de nitruro de carbono ricos
James R Holst1, Edward G Gillan
1Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, USA.
Journal of the American Chemical Society
|May 21, 2008
Resumen
Los materiales de hidróxido de carbono de nitrógeno formados a partir de precursores de triazina contienen principalmente estructuras de heptazina, no sólo unidades de triazina. Este hallazgo tiene un impacto en la comprensión y aplicación de estos materiales versátiles de nitruro de carbono.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Química Química es la química.
- Nanotecnología La nanotecnología es la nanotecnología.
Sus antecedentes:
- Los materiales de nitruro de carbono ricos en nitrógeno (CN x H y) se sintetizan típicamente a través de la termólisis de los precursores a altas temperaturas (> 500 ° C).
- Las estructuras amorfas de CN x a menudo se modelan utilizando unidades de triazina (C 3N 3) entrelazadas.
- Estudios recientes sugieren que las unidades más grandes de heptazina (C 6N 7) pueden ser más frecuentes en ciertas redes de nitruro de carbono.
Objetivo del estudio:
- Reexaminar las estructuras locales en las redes amorfas de nitruro de carbono derivadas de los precursores de triazina.
- Para investigar la formación y estructura de CN x H y sintetizado a partir de un precursor reactivo de triazina a temperaturas moderadas.
Principales métodos:
- Síntesis de CN x H y a partir de la tricloromelamina (C 3N 3 ((NHCl) 3) a través de una descomposición rápida y exotérmica.
- Análisis utilizando espectrometría de masas de gases de subproducto, espectroscopia de RMN e IR, hidrólisis de base y análisis cristalográfico.
Principales resultados:
- La descomposición de la tricloromelamina a ~400°C conduce a la fragmentación y reorganización de los anillos.
- El producto CN x H y resultante contiene predominantemente bloques estructurales más grandes, similares a las heptazinas.
- Esto contrasta con la visión tradicional de las estructuras basadas en triazina en materiales similares.
Conclusiones:
- La descomposición a temperatura moderada de los precursores de triazina produce materiales CN x H y con estructuras similares significativas a las heptazinas.
- Estos hallazgos requieren una reevaluación de los modelos estructurales para los nitritos de carbono amorfos derivados de la termólisis de la triazina.
- Proporciona una mejor comprensión estructural para aplicaciones en fotoactividad y como soportes de coordinación.
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