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Interacciones ion-hidrocarburo y/o ion-ion: efectos directos y inversos de Hofmeister en un huésped sintético
Jacobs H Jordan1, Corinne L D Gibb1, Anthony Wishard1
1Department of Chemistry , Tulane University , New Orleans , Louisiana 70118 , United States.
Journal of the American Chemical Society
|March 14, 2018
Resumen
Los aniones polarizables desencadenan los efectos de Hofmeister y revierten los efectos de Hofmeister en una molécula huésped con sitios de unión distintos. La unión de aniones causa atenuación de carga, agregación y precipitación, lo que demuestra un comportamiento complejo de la solución.
Área de la Ciencia:
- Química supramolecular
- Química Física
- Química de la solución
Sus antecedentes:
- El efecto Hofmeister describe las perturbaciones específicas de iones de la solubilidad y el comportamiento de las proteínas.
- Comprender las interacciones huésped-huésped es crucial para diseñar sistemas moleculares funcionales.
- La unión aniónica en receptores sintéticos puede modular las propiedades de la solución.
Objetivo del estudio:
- Investigar la influencia de los aniones polarizables en la complejación huésped-huésped.
- Para aclarar los mecanismos detrás de Hofmeister y revertir los efectos de Hofmeister en un huésped sintético.
- Caracterizar las afinidades y selectividades de unión de aniones a diferentes sitios dentro del huésped.
Principales métodos:
- Espectroscopia de resonancia magnética nuclear de protones (RMN) para sondear las interacciones de unión.
- Diseminación dinámica de la luz (DLS) para evaluar el tamaño y la agregación de partículas.
- Mediciones de turbidez para el seguimiento de la precipitación.
Principales resultados:
- Los aniones exhiben afinidades comparables tanto para el bolsillo no polar "blando" como para los sitios de cationes de amonio "duros".
- La unión de aniones a bajas concentraciones (∼2 mM) induce el efecto Hofmeister en la unión huésped-invitado.
- La unión de aniones conduce a la atenuación de la carga, la agregación y la precipitación (efecto Hofmeister inverso).
- El bloqueo de la bolsa no polar atenúa el efecto Hofmeister inverso.
Conclusiones:
- Los aniones polarizables inducen tanto los efectos de Hofmeister como los inversos en el huésped estudiado.
- Los distintos sitios de unión del huésped juegan un papel crítico en la mediación de estos efectos.
- La precipitación inducida por aniones está vinculada a la atenuación y agregación de cargas, modulada por interacciones específicas en el sitio de unión.
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