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El diseño racional de los catalizadores organofotoredóxicos reductores desbloquea los mecanismos de polimerización

Tommaso Bortolato¹, Gianluca Simionato¹, Marie Vayer²

¹Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy.

Journal of the American Chemical Society

|January 6, 2023

Resumen

Los nuevos fotocatalizadores orgánicos (PC), las dihidroacridinas de 9-arilo (9ADA) y las dihidrobenzoacridinas de 12-arilo (12ADBA), permiten nuevas reacciones químicas. Su estructura única facilita la transferencia de electrones acoplados a protones para reducir sustratos difíciles con luz visible.

Área de la Ciencia:

Química orgánica
Fotocatálisis
Ciencias de los materiales

Sus antecedentes:

La fotocatálisis orgánica es crucial para el desarrollo de nuevas transformaciones químicas.
Un número limitado de fotocatalizadores orgánicos versátiles (PC) dificultan la exploración de nuevas reactividades.
Hay necesidad de nuevos PC orgánicos con propiedades sintonizables y aplicaciones más amplias.

Objetivo del estudio:

Diseñar y caracterizar nuevos fotocatalizadores orgánicos reductores fuertes.
Investigar las relaciones estructura-propiedad de estos nuevos fotocatalizadores.
Explorar sus aplicaciones en la catálisis fotorredóxica y la polimerización.

Principales métodos:

Síntesis y caracterización fisicoquímica completa de las dihidroacridinas de 9-arilo (9ADA) y las dihidrobenzoacridinas de 12-arilo (12ADBA).
Modulación de las distribuciones orbitales moleculares y estados excitados (excitados localmente y transferencia de carga).
Evaluación del rendimiento fotocatalítico en la desfuncionalización por fotorreducción y la polimerización de radicales por transferencia atómica.

Principales resultados:

9ADA y 12ADBA se sintetizaron con éxito y se caracterizaron como PC orgánicos reductores potentes.
Los PC excitados localmente sobresalieron en la desfuncionalización por fotorreducción (hasta un 92% de rendimiento).
Los PC de estado excitado por transferencia de carga mostraron ser prometedores en la polimerización radical de transferencia de átomos de luz visible (hasta 1,21 Đ, 98% I*).
El grupo NH libre permitió un mecanismo catalítico de transferencia de electrones acoplados a protones (MS-PCET).
Se logró la reducción de sustratos redox-inertes (haluros, azidos, sales) con potenciales de reducción tan bajos como -2,83 frente a SCE.

Conclusiones:

9ADA y 12ADBA representan una nueva clase de fotocatalizadores orgánicos con propiedades electrónicas sintonizables.
Su mecanismo MS-PCET único permite la reducción de sustratos redox inertes desafiantes a través de la excitación de un solo fotón.
Se espera que estos nuevos fotocatalizadores amplíen el alcance de la generación de radicales y las transformaciones orgánicas bajo luz visible.

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