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Creación de geometrías favorables para dirigir las fotorreacciones orgánicas en monocapas de alkanetiolato

Moonhee Kim¹, J Nathan Hohman, Yang Cao

¹California NanoSystems Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA.

Science (New York, N.Y.)

|March 12, 2011

Resumen

Los investigadores utilizaron sitios de defectos en monocapas autoensambladas para guiar reacciones fotoquímicas desfavorables de moléculas orgánicas. Este método permitió la observación de la conmutación molecular y las transformaciones fotoquímicas mediante el uso de microscopía de túnel de barrido (STM).

Área de la Ciencia:

Ciencias de la superficie Ciencias de la superficie.
La fotoquímica es la fotoquímica.
La electrónica molecular es la electrónica molecular.

Sus antecedentes:

Las reacciones fotoquímicas de moléculas orgánicas conjugadas a menudo están limitadas por geometrías desfavorables en solución.
Las monocapas autoensambladas (SAM) en las superficies ofrecen una plataforma para controlar los arreglos moleculares.

Objetivo del estudio:

Investigar el uso de sitios de defectos en SAMs de alkanetiolato para dirigir reacciones fotoquímicas geométricamente desfavorables.
Observar y caracterizar in situ las transformaciones fotoquímicas de las moléculas orgánicas individuales.

Principales métodos:

Utilizó microscopía de túnel de barrido (STM) para estudiar moléculas dentro de monocapas de alcanetiolato en superficies de oro.
Utilizó luz ultravioleta (UV) durante la toma de imágenes STM para inducir y sondear reacciones fotoquímicas.
Se analizó la conductividad molecular y el comportamiento de conmutación.

Principales resultados:

Dirigió con éxito reacciones fotoquímicas geométricamente desfavorables utilizando sitios de defectos en SAM.
Se observó alta conductividad y conmutación estocástica en feniletiniliolatos terminados en antracenos.
Se distinguen las transformaciones fotoquímicas in situ a través de STM.
Se observó un aumento de las alturas moleculares aparentes en las imágenes de STM tras la excitación UV, lo que indica la detección de estados excitados electrónicamente.

Conclusiones:

Los sitios de defectos en los SAM pueden controlar efectivamente las geometrías de reacción fotoquímica.
El STM es una poderosa herramienta para observar las transformaciones fotoquímicas a nivel de una sola molécula.
El estudio proporciona información sobre la exploración de los estados excitados electrónicamente de las moléculas en las superficies.

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