This bicyclic compound consists of the fusion of benzene and imidazole. Imidazolidinones are a class of 5-membered ring heterocycles structurally related to imidazole. This is treated with iodine, triphenyl phosphine, and imidazole to form 2-iodo-3-(2-iodoethyl)-1H-indole. The imidazole/imidazolium ring of histidine is aromatic at all pH values. In the presence of an imidazole ligand, this ferrous complex reversibly binds O. The most pervasive is the amino acid histidine, which has an imidazole side-chain. These salts are formed from the protonation or substitution at nitrogen of imidazole. Ketoconazole was introduced as the prototypical medication of the imidazole group of antifungals. The xanthine core of caffeine contains two fused rings, a pyrimidinedione and imidazole. Deprotonation gives the imidazole anion, which is symmetrical. Econazole is an antifungal medication of the imidazole class. After, His3 forms imidazole acetol-phosphate releasing water. Many natural products, especially alkaloids, contain the imidazole ring. Losartan carries a heterocycle imidazole while valsartan carries a nonplanar acylated amino acid. SpyDock-bound proteins are eluted by incubating the resin with 2.5 M imidazole in neutral buffer.