Steroids as organising elements in anion receptors

The steroid nucleus has proved useful in various areas of supramolecular chemistry, acting as a building-block for extended, well-defined molecular architectures, and a scaffold for preorganised arrays of functionality. This article discusses its applications in the area of anion recognition, where cholic acid (2) has been especially valuable. The three secondary hydroxyl groups on 2 are nicely arranged for H-bond donation to a single anion, and may be converted into stronger neutral or positively-charged H-bond donors. Macrocyclic and acyclic receptors derived from 2 have been used to bind inorganic anions, carboxylates and nucleic acids. (C) 2003 Elsevier Science B.V. All rights reserved.