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Complejos de muñecas de anidación rusas de cestas moleculares y zinc que contienen ligandos de TPA
Lei Zhiquan1, Shane Polen1, Christopher M Hadad1
1Department of Chemistry and Biochemistry, The Ohio State University , 100 West 18th Avenue, Columbus, Ohio 43210, United States.
Journal of the American Chemical Society
|June 16, 2016
Resumen
Este estudio muestra que las cestas moleculares pueden encapsular complejos metálicos, creando nuevas estructuras. Las cestas enantiopuras transfieren quiralidad, lo que permite nuevas aplicaciones de discriminación catalítica y quiral para los complejos metálicos de tris ((2-piridilmetil) amina (TPA).
Área de la Ciencia:
- Química supramolecular
- Química de coordinación
- Reconocimiento quiral
Sus antecedentes:
- Los complejos metálicos de Tris2-piridil) amina (TPA) son importantes en la catálisis.
- El diseño de arquitecturas moleculares para controlar las propiedades complejas del metal es un desafío clave.
- Las interacciones de la segunda esfera de coordinación pueden influir en la reactividad y la selectividad.
Objetivo del estudio:
- Para investigar la complejación de un complejo Zn(II) - TPA dentro de cestas moleculares cóncavas.
- Para explorar la transferencia de quiralidad de una cesta enantiopura al complejo metálico encapsulado.
- Evaluar el potencial de mejora de la función catalítica y la discriminación quiral de los complejos de TPA.
Principales métodos:
- Síntesis y caracterización del complejo convexo Zn(II) - TPA (1) y las cestas cóncavas (2 y 3).
- Espectroscopia de resonancia magnética nuclear (RMN) y espectrometría de masas para confirmar la formación del complejo.
- Espectroscopia de dicroísmo circular (CD) para estudiar la transferencia quiral y los cambios estructurales.
Principales resultados:
- La cesta 2 atrapó con éxito el complejo Zn(II) -TPA (1) en agua, formando un complejo 1:1 con una constante de unión de (2.0 ± 0.2) × 10(3) M(-1).
- La canasta de enantiopuro 3, funcionalizada con (S) -alanina, transfirió su quiralidad estática al complejo encapsulado Zn(II) -TPA.
- Esta transferencia quiral indujo un giro helicoidal izquierdo (M) en los anillos de piridina del ligando TPA a través de contactos iónicos intermoleculares.
Conclusiones:
- Las cestas moleculares pueden actuar efectivamente como segundas esferas de coordinación para los TPA que contienen metales.
- Las cestas enantiopuras pueden impartir quiralidad a los complejos metálicos achirales, lo que lleva a las hélices quirales.
- Estos hallazgos ofrecen una vía para mejorar las capacidades de discriminación catalítica y quiral de los sistemas basados en TPA.
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