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Complejos de Iridio Zwitteriónico Fosforescente Azul (III) con ligandos basados en nido-carborano de baja

Jonathan C Axtell¹, Kent O Kirlikovali¹, Peter I Djurovich²

¹Department of Chemistry and Biochemistry, University of California, Los Angeles , 607 Charles E. Young Drive East, Los Angeles, California 90095, United States.

Journal of the American Chemical Society

|December 10, 2016

Resumen

Los investigadores desarrollaron nuevos complejos de iridio fosforescente utilizando ligandos de carboranilo de baja coordinación. Estos emisores azules robustos y altamente luminiscentes muestran una mejora de rendimiento cuántico de 10 veces, allanando el camino para materiales fosforescentes eficientes.

Área de la Ciencia:

Química organometálica
Ciencias de los materiales
La fotofísica

Sus antecedentes:

Los complejos de iridio (III) son cruciales para las aplicaciones fosforescentes.
El desarrollo de emisores eficientes y estables sigue siendo un desafío clave.
Los ligandos de carboranilo ofrecen propiedades electrónicas y estéricas únicas.

Objetivo del estudio:

Síntesis y caracterización de una nueva clase de compuestos fosforescentes zwitteriónicos bis (heterolepticos) de iridio (III).
Investigar el impacto de los sustituyentes de nidocarboranilo de baja coordinación en las propiedades de luminiscencia.
Explorar nuevas estrategias de diseño de ligandos para emisores mejorados de iridio.

Principales métodos:

Síntesis de precursores de iridio y su reacción con orto-carboranilpiridinas sustituidas por C.
Caracterización de los complejos metálicos resultantes mediante técnicas espectroscópicas y estructurales.
Evaluación de las propiedades fotofísicas, incluidas las longitudes de onda de emisión, el rendimiento cuántico y la estabilidad térmica.

Principales resultados:

Formación de complejos de bis (heteroleptic) iridio (III) robustos y altamente luminiscentes con ligandos de nido-carboranilo.
La fosforescencia azul se observa a 450-470 nm tanto en la solución como en la matriz de PMMA.
Se obtienen rendimientos cuánticos superiores al 40%, una mejora de 10 veces con respecto a los análogos de carboranilo vinculados covalentemente.
Estabilidad estructural demostrada a temperaturas superiores a 300 °C.

Conclusiones:

Los ligandos de nido-carboranilo de coordinación débil facilitan la desboronación fácil y forman complejos de iridio (III) luminiscentes estables.
Las interacciones electrostáticas entre el fragmento de nido-carboranilo y el centro Ir (III) mejoran la luminiscencia.
Esta estrategia de diseño de ligandos ofrece una ruta prometedora para el desarrollo de emisores de iridio fosforescente altamente eficientes.

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