The calix[4]pyrroles are a class of old but new heterocalixarene analogues that show interesting anion and neutral substrate binding properties. Calix[4]pyrroles are easy to make and functionalize. As such, they have been employed in the production of separation media for anionic and neutral species. Calixpyrroles also provide useful precursors for the generation of novel calixpyridinopyrroles and calixpyridines.