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Propiedades fotofísicas de las cintas de porfirina
Hyun Sun Cho1, Dae Hong Jeong, Sung Cho
1Center for Ultrafast Optical Characteristics Control and Department of Chemistry, Yonsei University, Seoul 120-749, Korea.
Journal of the American Chemical Society
|December 6, 2002
Resumen
Las nuevas cintas de zinc fundido ((II) porfirina (Tn) muestran una rápida formación de estado excitado y una relajación acelerada, en contraste con las matrices ortogonales. Estas propiedades sugieren aplicaciones en electrónica y óptica.
Área de la Ciencia:
- Química supramolecular de las moléculas.
- La fotofísica es la fotofísica.
- Ciencia de los materiales Ciencia de los materiales.
Sus antecedentes:
- Las matrices de porfirina se investigan por sus propiedades fotofísicas únicas.
- Las estructuras de porfirina fundida ofrecen nuevas características electrónicas y ópticas.
Objetivo del estudio:
- Para investigar las propiedades fotofísicas de las nuevas matrices de porfirina de Zn(II) fundido (cintas de porfirina, Tn).
- Para comparar las propiedades de estas matrices fundidas con matrices de porfirina ortogonales.
- Para explorar las posibles aplicaciones de las cintas de porfirina.
Principales métodos:
- Mediciones espectroscópicas de estado estacionario y resolución de tiempo.
- Cálculos teóricos del orbital molecular (MO, por sus siglas en inglés) (PPP-SCI).
Principales resultados:
- Los espectros de absorción de las cintas de porfirina se desplazan a la región IR con el aumento del número de pigmentos.
- Formación rápida de estado excitado (aprox. 500 fs para T2) a través de la conversión interna, más rápido que el monómero Zn(II) porfirina (1.2 ps).
- La relajación del estado excitado se acelera con el aumento de las unidades de porfirina (4,5 ps para el dimer T2 a 0,3 ps para el hexamer T6), explicado por la ley de la brecha de energía.
- El carácter del excitón de tipo Wannier en el estado excitado más bajo de las cintas de porfirina, a diferencia de los excitones de tipo Frenkel en matrices directamente vinculadas.
Conclusiones:
- Las cintas de porfirina fundida exhiben propiedades fotofísicas únicas distintas de las matrices ortogonales.
- Las propiedades observadas se atribuyen a la estructura plana fundida y al comportamiento del excitón.
- Las cintas de porfirina muestran potencial para aplicaciones como cables eléctricos, sensores IR y materiales ópticos no lineales.
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