422 Anionic Macrocyclic Receptors: Internal and External Binding

Friday, November 6, 2009: 2:20 PM
Rio Grande (Camino Real Hotel)
Jorge Tiburcio , Department of Chemistry, Cinvestav, Mexico City, Mexico
The presence of functional groups in crown ethers can modulate their electronic properties without drastically modifying its basic structure and cavity size. Even more, electrically charged anionic functional groups (i.e. sulfonate, carboxilate, phosphonate) could have an important effect on the association constants, especially with cationic species. Another interesting effect would be the solubility, whereas crown ethers are usually insoluble in water, the anionic derivatives have a good chance of being water soluble, allowing association phenomena in aqueous solution been investigated. In this contribution we will present the chemical transformation of dibenzo-24-crown-8 ether to a bis(sulfonated) version. The separation and properties of the two isomers (syn and anti) generated in the sulfonation reaction will be discussed. The different binding motifs observed for this crown ether with pyridinium and benzimidazolium cationic species, especially in aqueous solution, will be also presented.