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La actividad óptica y la anisotropía óptica en los cristales fotomecánicos de las salicilidenefeniletilaminas
Akifumi Takanabe1, Masahito Tanaka2, Kohei Johmoto3
1Department of Advanced Science and Engineering, Graduate School of Advanced Science and Engineering, Waseda University , 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
Journal of the American Chemical Society
|October 25, 2016
Resumen
Los cristales fotomecánicos quirales exhiben movimientos únicos de flexión y torsión al exponerse a la luz UV. Sus propiedades quirópticas y ópticas, medidas por G-HAUP, revelan diferencias significativas entre los estados de cristal y solución, mejorando el control de movimiento mecánico.
Área de la Ciencia:
- Ciencias de los materiales
- La cristalografía
- La fotoquímica
Sus antecedentes:
- La introducción de la quiralidad en los cristales fotomecánicos diversifica el movimiento mecánico.
- Los cristales quirales son cruciales para evaluar las propiedades fotomecánicas.
- Los enantiómeros fotocrómicos de N-3,5-di-tert-butilsalicileno-1-feniletilamina exhiben efectos fotomecánicos.
Objetivo del estudio:
- Para medir y analizar las propiedades quirópticas y ópticas anisotrópicas de los cristales fotomecánicos quirales.
- Evaluar el impacto de la irradiación UV en estas propiedades.
- Para entender la relación entre la estructura cristalina y el movimiento fotomecánico.
Principales métodos:
- Medición simultánea de espectros ópticos anisotrópicos (birefringencia lineal, LB; dicroísmo lineal, LD) y quirópticos (birefringencia circular, CB; dicroísmo circular, CD) mediante el polarimetro universal generalizado de alta precisión (G-HAUP).
- Irradiación con luz UV de cristales en forma de placa de los enantiómeros S y R.
- Análisis de la estructura cristalina y comparación con la solución y los datos computacionales.
Principales resultados:
- La irradiación UV indujo el movimiento de flexión y torsión en los cristales debido a la contracción anisotrópica.
- Se observaron picos de LD distintos a 330 nm y efectos de CD Cotton a 330 nm y 460 nm.
- Los espectros CB y CD en cristales contrastados con las mediciones y simulaciones de la solución.
- El parámetro de disimetría (g) en cristales fue significativamente mayor que en solución o valores calculados.
Conclusiones:
- La quiralidad en cristales fotomecánicos permite movimientos mecánicos complejos.
- G-HAUP es eficaz para caracterizar las propiedades quirópticas y ópticas de los cristales quirales.
- Existen diferencias significativas en las propiedades quirópticas entre los estados cristalino y de solución.
- El empaque y la estructura de cristal mejoran las respuestas quirópticas, ofreciendo potencial para dispositivos fotomecánicos avanzados.
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