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Boranos de amonio para la complejación selectiva de iones de cianuro o fluoruro en el agua
Todd W Hudnall1, François P Gabbaï
1Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA.
Journal of the American Chemical Society
|September 12, 2007
Resumen
Dos boranos de amonio isoméricos se unen selectivamente ya sea con iones de cianuro o fluoruro en soluciones acuosas. Este descubrimiento ofrece potencial para el desarrollo de nuevos sensores para la detección específica de aniones.
Área de la Ciencia:
- Química supramolecular de las moléculas.
- Reconocimiento Anion Reconocimiento Anion
- Química del boro y su química.
Sus antecedentes:
- Los boranos catiónicos se exploran para la unión de aniones.
- Las estructuras isoméricas pueden dar lugar a diferentes propiedades de unión.
- La detección selectiva de aniones en medios acuosos sigue siendo un desafío.
Objetivo del estudio:
- Para investigar las propiedades de unión aniónica de dos boranos de amonio isoméricos, [p-(Mes2B) C6H4 (((NMe3)) ]+ ([1]+) y [o- ((Mes2B) C6H4 (((NMe3)) ]+ ([2]+).
- Para determinar la selectividad de estos boranos para los iones fluoruro y cianuro en solución acuosa.
- Para aclarar los factores estructurales y electrónicos que rigen su unión selectiva de aniones.
Principales métodos:
- Síntesis de boranos de amonio para y ortoisoméricos.
- Investigación experimental de la unión de aniones utilizando técnicas como la espectroscopia de RMN (implicada).
- Estudios computacionales (por ejemplo, DFT) para comprender los mecanismos de unión y la selectividad.
Principales resultados:
- Ambos boranos ([1]+ y [2]+) se unen a los iones fluoruro y cianuro en los disolventes orgánicos.
- En solución acuosa, [1]+ se une selectivamente con el cianuro (K = 3,9 x 10^8 M−1).
- [2]+ se une selectivamente con el fluoruro (K = 910 M−1).
- Los efectos estéricos y electrónicos dictan la selectividad observada.
- La unión es reversible y selectiva frente a otros aniones comunes.
Conclusiones:
- El para-isómero [1]+ exhibe una alta afinidad con el cianuro debido a los efectos de Coulombic.
- El orto-isómero [2]+ se une al fluoruro debido a la acidez de Lewis mejorada del centro de boro.
- Estos boranos isoméricos demuestran una notable selectividad para aniones específicos en el agua, allanando el camino para aplicaciones específicas de detección de aniones.
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