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Conmutación molecular a través de vías de fotoisomerización E/Z exclusivas de la multiplicidad

Jiawang Zhou¹, Xin Guo², Howard E Katz^1,2

¹Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States.

Journal of the American Chemical Society

|August 11, 2015

Resumen

Este estudio revela que la fotoisomerización E/Z del 1,2-dietienil-1,2-dicianoteno (4TCE) se produce a través de distintas vías de espín. Este mecanismo de exclusión de la multiplicidad permite un control predecible sobre los materiales fotointercambiables mediante la sintonización de la estructura molecular.

Área de la Ciencia:

La fotoquímica
Ciencias de los materiales
Química Física

Sus antecedentes:

Los materiales fotointercambiables ofrecen respuestas sintonizables basadas en estímulos externos.
Comprender los mecanismos de fotoisomerización es crucial para controlar las propiedades del material.
El 1,2-dietienil-1,2-dicianeteno (4TCE) es un interruptor de luz visible activado por la luz.

Objetivo del estudio:

Caracterizar los mecanismos de fotoisomerización E/Z del 4TCE.
Investigar el papel de la multiplicidad de espín en el control de las vías de fotoisomerización.
Para explorar el potencial para adaptar el rendimiento del interruptor fotográfico.

Principales métodos:

Se utilizó la espectroscopia de absorción transitoria ultra rápida para estudiar el 4TCE en el clorobenzeno.
Se realizaron cálculos químicos cuánticos para apoyar la interpretación de la vía fotofísica.
Se llevaron a cabo experimentos de transferencia de energía con triplet.

Principales resultados:

La isomerización trans-to-cis ocurre exclusivamente dentro del colector singlet (40 ps).
La isomerización cis-trans procede a través del cruce intersistémico (ISC) dentro y fuera del colector de tripletes (∼2 ps y 0.4 ns) a energías más altas.
La superficie de energía potencial T1 no tiene barreras, y las superficies S1/T1 exhiben un acoplamiento spin-orbital significativo.

Conclusiones:

4TCE exhibe vías de conmutación E/Z exclusivas de la multiplicidad.
Este exclusivo control de la vía ofrece un método para la manipulación predecible de los materiales fotoswitchable.
Los acoplamientos de espín-órbita se pueden modular a través de la estructura molecular o el entorno para adaptar el rendimiento del interruptor.

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