Anion receptor chemistry: highlights from 2007.

This critical review includes advances in anion complexation in the year 2007. The review covers anion receptors that employ amides and thioamides, pyrroles and indoles, ureas and thioureas, guanidinium, ammonium, and imidazolium groups and receptors containing hydroxyl groups. In addition, receptors containing metal ions or Lewis acids are discussed along with anion-pi interactions and the membrane transport of anionic species by synthetic transporters and channels (204 references).