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Complejos de racimos de oro (I) -plata (I) intensamente luminiscentes con características estructurales ajustables.
Quan-Ming Wang1, Young-A Lee, Olga Crespo
1Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.
Journal of the American Chemical Society
|August 5, 2004
Resumen
Nuevos cúmulos luminiscentes de oro y plata con una estructura tetraédrica única exhiben colores de emisión sintonizables de azul a naranja, dependiendo del átomo de calcógeno puente. Esta investigación introduce el primer sistema luminiscente de oro oxo.
Área de la Ciencia:
- Química Inorgánica La Química Inorgánica es la química inorgánica.
- Ciencia de los materiales Ciencia de los materiales.
- La fotoquímica es la fotoquímica.
Sus antecedentes:
- Los complejos de oro (I) y plata (I) son conocidos por sus interesantes propiedades fotofísicas.
- La metalophilicidad, la interacción atractiva entre los centros metálicos, juega un papel crucial en la estructura y la luminiscencia de los complejos metálicos de monedas.
- Los elementos del grupo 16 (calcógenos) pueden actuar como ligandos puentes, influyendo en las propiedades electrónicas y ópticas de los grupos metálicos.
Objetivo del estudio:
- Para sintetizar y caracterizar una nueva serie de complejos isostruturales oro-plata.
- Investigar el efecto de diferentes átomos del grupo-16 (O, S, Se) en las propiedades luminiscentes de estos complejos.
- Explorar las características estructurales y fotofísicas de los sistemas de oro (I) oxo y sus análogos.
Principales métodos:
- Síntesis y caracterización de complejos oro-plata utilizando técnicas como la cristalografía de rayos X.
- Espectroscopia de fotoluminiscencia para estudiar las propiedades de emisión (energía, vida útil).
- Estudios de temperatura variable (medidas de vidrio congelado) para sondear estados excitados.
Principales resultados:
- Sintetizó con éxito complejos isostruturales [Au3(mu3-E) Ag(PPh2py)3](BF4)2 donde E = O, S, Se.
- Se observaron cambios notables en la energía de emisión (azul a naranja) con la variación del átomo de calcógeno puente (O a Se).
- Se informó de la primera luminiscencia para un sistema de oro ((I) oxo (E=O).
- La caracterización estructural reveló un núcleo de tetraedro Au3Ag con interacciones aerofílicas no soportadas en estado sólido.
- Las mediciones de la duración de la luminiscencia sugieren una naturaleza de espín prohibido para el estado excitado en los sistemas E=S y E=Se.
- Las mediciones de vidrio congelado indicaron un estado de emisión de energía más alta para estos sistemas.
Conclusiones:
- La energía de emisión de estos cúmulos de oro y plata es ajustable mediante la alteración del átomo de calcógeno puente, lo que permite la afinación del color.
- Las propiedades de luminiscencia se atribuyen a la transferencia de carga de ligando a metal a ligando (LMMCT) o a las transiciones basadas en racimos centrados en el metal.
- Estos hallazgos proporcionan una base para el diseño de nuevos materiales luminiscentes basados en complejos oro-plata polinucleares.
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