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Tetra-TTF calix[4]pyrrole: un receptor racionalmente diseñado para huéspedes neutros con déficit de electrones
Kent A Nielsen1, Won-Seob Cho, Jan O Jeppesen
1Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, 1 University Station-A5300, Texas 78712-0165, USA.
Journal of the American Chemical Society
|December 17, 2004
Resumen
Este estudio introduce un nuevo tetra-tetratiafulvaleno (TTF) calix[4]pyrrole capaz de unirse a huéspedes con déficit de electrones. Los iones de cloruro desencadenan un cambio conformacional, liberando las moléculas huéspedes unidas.
Área de la Ciencia:
- Química supramolecular de las moléculas.
- Síntesis orgánica La síntesis orgánica.
- Ciencia de los materiales Ciencia de los materiales.
Sus antecedentes:
- Los derivados de pirrol de Calix[4] son versátiles huéspedes macrocíclicos.
- Las unidades de tetratiofulvaleno (TTF) son conocidas por sus propiedades donantes de electrones y su actividad redox.
- El diseño de receptores para huéspedes neutros y con déficit de electrones sigue siendo un desafío en la química supramolecular.
Objetivo del estudio:
- Para sintetizar un nuevo calix[4]pirrole añadido con cuatro unidades de tetratiafulvaleno (TTF).
- Para investigar el comportamiento de complejación huésped-huésped de este calix tetra-TTF[4]pirrole con moléculas neutras con déficit de electrones.
- Para explorar el efecto de los estímulos externos, como los iones de cloruro, en el complejo huésped-huésped.
Principales métodos:
- Síntesis del calix tetra-TTF[4]pyrrole. también conocido como calix.
- Estudios de estado de solución utilizando espectroscopia UV-vis y 1H RMN.
- Análisis del estado sólido a través de la cristalografía de rayos X.
- Investigación de la liberación del huésped desencadenada por iones de cloruro.
Principales resultados:
- La síntesis exitosa del calix tetra-TTF[4]pyrrole. fue lograda.
- Formación de complejos tipo sándwich 1:2 con huéspedes como el 1,3,5-trinitrobenzeno, la tetrafluoro-p-benzoquinona y la tetracloro-p-benzoquinona.
- Estabilización compleja a través de las interacciones de transferencia de carga y enlace de hidrógeno en la conformación 1,3-alternativa.
- La adición de iones de cloruro indujo un cambio conformacional de 1,3-alternativo a cono, lo que condujo a la liberación del huésped.
Conclusiones:
- El calix[4]pyrrole tetra-TTF actúa como un receptor efectivo para los huéspedes con déficit de electrones neutros.
- La complejación anfitrión-invitado está regida por la transferencia de carga y el enlace de hidrógeno.
- Los iones de cloruro pueden actuar como un disparador para modular la conformación del receptor y liberar a los huéspedes atados.
- Este trabajo demuestra un sistema supramolecular sensible al estímulo con aplicaciones potenciales en la detección o separación.
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