Synthesis and binding pattern of Calix[4]Pyrrole compounds

In this short review, focus has been on the improvisations in the synthetic procedures of the Calix[4] pyrrole type compounds, since their first discovery in the year 1886 and subsequent discussion on their binding pattern towards different chemical species. Calix[4] pyrrole, which is an analogue of hetero calixarenes, is the representative of a group of macrocycles. It has an ability to bind neutral and anionic species. The selectivity towards guest species emerges from the energetics and conformational features of this compound. Different structural modifications and fuctionalizations have been incorporated in the parent Calix[4] pyrrole moiety in order to achieve better selectivity.