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Conductores moleculares de radicales neutrales basados en fenalenilo: efectos sustituyentes en las estructuras y
Sushanta K Pal1, Mikhail E Itkis, Fook S Tham
1Department of Chemistry, University of California, Riverside, California 92521-0403, USA.
Journal of the American Chemical Society
|May 16, 2007
Resumen
Los nuevos radicales orgánicos exhiben estructuras inusuales de cadena pi unidimensional, que muestran propiedades metálicas y un estado básico de enlace de valencia resonante. Estos hallazgos avanzan en la comprensión de los nuevos materiales orgánicos y su comportamiento electrónico.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Química orgánica es la química orgánica.
- Física del estado sólido Física del estado sólido
Sus antecedentes:
- Los radicales de spirobiphenalenyl son una clase de compuestos orgánicos con propiedades electrónicas únicas.
- Comprender su estructura de estado sólido y su comportamiento magnético es crucial para el desarrollo de nuevos materiales electrónicos orgánicos.
Objetivo del estudio:
- Para sintetizar y caracterizar cicloheptyl y radicales de spirobiphenalenyl sustituidos por cyclooctyl y sus dímeros.
- Para investigar el embalaje en estado sólido, las propiedades magnéticas y la estructura electrónica de estos nuevos compuestos.
Principales métodos:
- Cristalización y caracterización del estado sólido (difracción de rayos X).
- Las mediciones de la susceptibilidad magnética (paramagnetismo de Pauli, antiferromagnetismo de Heisenberg).
- Mediciones de conductividad eléctrica.
- Cálculos ampliados de Hückel y DFT para la estructura electrónica.
Principales resultados:
- El radical cicloheptilo (9) forma una estructura monomérica de cadena pi, exhibiendo paramagnetismo de Pauli independiente de la temperatura y un estado fundamental de enlace de valencia resonante.
- El derivado del cicloctilo existe tanto como un pi-dimero diamagnético (10) como como un sigma-dimero diamagnético (10d).
- El Compuesto 9 muestra características de metal orgánico unidimensional con un ancho de banda de 0.4 eV y una conductividad de 1.5x10(-3) S/cm.
Conclusiones:
- El estudio revela un empaquetado inusual de la cadena pi 1D en el radical cicloheptyl spirobiphenalenyl, lo que lleva a un comportamiento metálico.
- Los hallazgos proporcionan información sobre la relación entre las propiedades magnéticas, la estructura electrónica y la organización del estado sólido en sistemas radicales orgánicos.
- Este trabajo contribuye al desarrollo de nuevos conductores orgánicos y materiales magnéticos.
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