The five-membered, aromatic, heterocyclic compound imidazole (C₃N₂H₄) was the subject of two unsuccessful searches, by Dezafra et al. in the 1970s and by Irvine et al in the 1980s. The earlier search was made with the old 140 foot telescope telescope at Green Bank observatory. The later search was made with the 20m millimeter wave telescope at Onsala Space Observatory in Sweden.

Imidazole is a well known organic compound, and it is a common component of many macromolecules. Perhaps most notably, is part of the amino acid histidine and thus commonly found in proteins and enzymes.