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Cianuros mixtos de cobre, plata y oro, (M(x) M'(1-x)) CN: estructuras de cadena de adaptación para influir en las
Ann M Chippindale1, Simon J Hibble, Edward J Bilbé
1Department of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, UK. a.m.chippindale@rdg.ac.uk
Journal of the American Chemical Society
|September 8, 2012
Resumen
Se sintetizaron y estudiaron nuevos cianuros de metales mixtos binarios (MCN). Estos compuestos exhiben un ordenamiento estructural y un enlace únicos, que influyen en sus propiedades de expansión térmica fotofísica y negativa.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Química del estado sólido.
- Química Inorgánica La Química Inorgánica es la química inorgánica.
Sus antecedentes:
- Los compuestos unidimensionales (1D) de cianuro metálico (MCN) son conocidos por sus interesantes propiedades estructurales y electrónicas.
- Las variantes de metales mezclados ofrecen oportunidades para ajustar estas propiedades a través del control de la composición.
Objetivo del estudio:
- Para sintetizar y caracterizar las variantes binarias de metales mixtos de los compuestos MCN (M = Cu, Ag, Au).
- Investigar el ordenamiento estructural, la unión metal-cianuro y las propiedades físicas resultantes (fotofísica, expansión térmica negativa) de estos nuevos materiales.
Principales métodos:
- Difracción de rayos X en polvo y difracción de neutrones totales para la determinación estructural.
- Espectroscopia vibratoria (infrarrojo y Raman) para el análisis de enlaces y ordenamiento de cianuro.
- Espectroscopia de reflectancia difusa y fotoluminiscencia para la caracterización de propiedades ópticas.
- Mediciones de expansión térmica para estudiar el comportamiento de la expansión térmica negativa (NTE).
Principales resultados:
- Se identificaron soluciones sólidas y fases de línea en sistemas de (Cu,Ag) CN y (Cu,Au) CN, (Ag,Au) CN, adoptando estructuras de AgCN o AuCN.
- Se observó un ordenamiento completo del cianuro metálico en (Cu(1/2) Au(1/2))CN y (Ag(1/2) Au(1/2))CN, con orientaciones de unión específicas determinadas.
- (Cu(0.50)Ag(0.50))CN mostró un ordenamiento incompleto con una preferencia por la unión de N al cobre.
- El enlace aurófilo no fue el factor principal para la adopción de la estructura AuCN.
- Las propiedades fotofísicas y el comportamiento de 1D NTE dependían fuertemente de la composición y el empaque de la cadena, con compuestos estructurados con AuCN que muestran una contracción mínima al calentarse.
Conclusiones:
- La síntesis de cianuros binarios de metales mixtos proporciona una ruta a nuevos materiales 1D con propiedades sintonizables.
- El ordenamiento estructural y el enlace metal-cianuro dictan los comportamientos fotofísicos y NTE observados.
- Los hallazgos desafían las suposiciones sobre las interacciones aurófilas en estos sistemas y resaltan las relaciones estructura-propiedad.
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