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Interacciones cooperativas huésped / huésped a través de la quelación asistida por conteriones: pseudorotaxanos de
Jason W Jones1, Lev N Zakharov, Arnold L Rheingold
1Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg 24061-0212, USA.
Journal of the American Chemical Society
|November 7, 2002
Resumen
La adición de aniones específicos a un complejo de éter de corona y paraquat mejora significativamente su interacción. Este enfoque de química supramolecular estabiliza el complejo huésped-invitado a través de la quelación cooperativa, aumentando la afinidad de unión.
Área de la Ciencia:
- Química supramolecular de las moléculas.
- Química entre anfitrión y huésped.
- Química Macrocíclica La Química Macrocíclica es la química macrocíclica en la que se encuentran las moléculas.
Sus antecedentes:
- Bis(5-hidroximetil-1,3-fenileno)-32-corona-10 es un huésped macrocíclico capaz de formar complejos.
- El paraquat es una molécula huésped que interactúa con huéspedes macrocíclicos.
- Los aniones que aceptan enlaces de hidrógeno pueden potencialmente modular las interacciones huésped-huésped.
Objetivo del estudio:
- Para investigar el efecto de los aniones di- o tritópicos en la interacción huésped-huésped entre un éter de corona específico y paraquat.
- Para cuantificar el aumento en la afinidad de unión.
- Para aclarar la base estructural de la mejora de la interacción observada.
Principales métodos:
- 1H espectroscopia de RMN para estimar las constantes de unión (Ka).
- Cristalografía de rayos X para determinar la base estructural de la formación compleja.
- Estudios de la fase de solución que involucran éter de corona, paraquat y varios aniones.
Principales resultados:
- La adición de Et4N+CF3COO- (tetraetilamonio trifluoroacetato) aumentó la afinidad de unión (Ka) en 14 veces.
- Se observaron aumentos similares en el Ka aparente con n-Bu4N+OTs- (tosilato de tetrabutylamonio).
- Las estructuras cristalinas revelaron la quelación de los grupos hidroxilo de éter de corona por los aniones, formando estructuras supramoleculares bicíclicas.
Conclusiones:
- Los aniones di- o tritópicos mejoran efectivamente la complejación huésped-huésped a través de la unión cooperativa.
- La quelación de los grupos hidroxilo del éter de la corona por aniones conduce a la formación de macrociclos supramoleculares estables y bicíclicos.
- Esta estrategia ofrece un método para estabilizar cooperativamente los complejos anfitrión-invitado, aumentando su afinidad de unión.
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