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Los dibenzobarlenos fotocrómicos: son intermediarios triplés birádicos de larga duración
Meledathu C Sajimon1, Danaboyina Ramaiah, Cherumuttathu H Suresh
1Photosciences and Photonics, Chemical Sciences and Technology Division and Computational Modeling and Simulation Section, National Institute for Interdisciplinary Science and Technology, Trivandrum, India.
Journal of the American Chemical Society
|July 13, 2007
Resumen
Los derivados de dibenzobarreleno exhiben fotocromatismo, cambiando de color bajo la luz UV. Este cambio de color se atribuye a un intermediario birrádico triple de larga vida, confirmado por estudios experimentales y teóricos.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La fotoquímica es la fotoquímica.
- La espectroscopia es una técnica de espectroscopia.
Sus antecedentes:
- Los materiales fotocrómicos cambian de color al exponerse a la luz.
- Los derivados del dibenzobarreleno son conocidos por sus propiedades fotoquímicas únicas.
- Comprender el mecanismo del fotocromismo es crucial para el desarrollo de nuevos materiales.
Objetivo del estudio:
- Para investigar el comportamiento fotocrómico de los derivados disubstituidos de dibenzobarreleno.
- Para dilucidar el mecanismo detrás de los cambios de color observados.
- Para caracterizar las especies intermedias involucradas en el proceso fotocrómico.
Principales métodos:
- Espectroscopia UV-Vis para monitorear cambios de color y determinar la cinética de la reacción.
- Estudios experimentales en fase sólida y en solución (benceno).
- Cálculos de la Teoría Funcional de Densidad (DFT), incluida la DFT dependiente del tiempo, para modelar vías de reacción y transiciones electrónicas.
Principales resultados:
- Los dibenzobarrelenos disubstituidos (1a, 1b, 1c) mostraron cambios de color reversibles tras la irradiación UV.
- La especie de color en 1a tiene una vida útil de 37 ± 2 s y es sensible al oxígeno.
- Los datos experimentales y teóricos apoyan fuertemente la formación de un intermediario triplo biradical de larga vida ((3) 2) responsable del fotocromismo.
Conclusiones:
- El fotocromismo de los dibenzobarrelenos implica un intermediario biradical triple.
- Los cálculos de DFT predicen con precisión el espectro de absorción del biradical.
- Los hallazgos proporcionan una comprensión mecanicista del fotocromismo en estos compuestos.
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