RESUMEN
The anion binding of tripodal hosts 2-4 has been studied. Increasing levels of conformational preorganisation of the side arms of the hosts led to increased (Cl-) unaltered (Br-) or decreased (NO3-) binding; it was thus possible to change guest selectivities by about an order of magnitude through conformational preorganisation of the flexible host.
Asunto(s)
Aniones/química , Modelos Químicos , Urea/química , Sitios de Unión , Evolución Molecular , Ligandos , Conformación Molecular , TermodinámicaRESUMEN
A set of three-armed urea-containing anion receptors was prepared. The receptors all have the same binding topology but differ in the level of conformational preorganization with respect to the arrangement of the side-arms relative to the platform and within the side arms themselves. This is mirrored in a specific increase (x 2.5) in the binding constant for chloride and in a 12-fold increase in the chloride/nitrate-selectivity.