What does heterocyclic mean?
Heterocyclic is a technical chemistry adjective describing a ring or ring system that contains more than one kind of atom. In most uses, the ring combines carbon with a heteroatom—typically nitrogen, oxygen, sulfur, or phosphorus—and the term may apply to the entire compound rather than only to its ring. This distinguishes heterocyclic molecules from carbocyclic ones, whose rings contain only carbon, and from acyclic molecules, which have no ring at all. The word appears frequently in discussions of pharmaceuticals, agrochemicals, dyes, and biomolecules because many biologically active and commercially useful compounds have heterocyclic cores. Familiar examples include the nitrogen-containing bases in DNA and RNA and the fused-ring structures of medicines such as caffeine. For general readers, “heterocyclic” identifies a broad and important family of organic molecules in which small differences among the atoms in a ring can substantially change a compound’s properties and biological activity.
adjectiveRelating to or consisting of a ring containing two or more kinds of atom, usually carbon together with one or more heteroatoms such as nitrogen, oxygen, or sulfur.
- Having or relating to a chemical ring that contains two or more kinds of atom.
"The researchers screened a library of heterocyclic compounds for antiviral activity."
"The researchers screened a library of heterocyclic compounds for antiviral activity."
"Each of the four nucleobases in DNA is a heterocyclic molecule."
DNA is written with heterocyclic letters: each of the four bases contains a ring made from carbon and nitrogen.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does heterocyclic come from?
Heterocyclic combines the Greek combining form hetero-, from heteros meaning “different,” with cyclic, based on Greek kyklos meaning “circle” and kyklikos meaning “pertaining to a circle.” The compound adjective developed in chemistry to distinguish rings containing different elements from carbocyclic rings, in which every ring atom is carbon. Its close chemical relatives include heterocycle and heterocyclization, the latter describing the formation of a heterocyclic ring.
Related word forms
How heterocyclic is actually used
This is a specialized, formal term used chiefly in chemistry and biochemistry. It commonly modifies words such as compound, ring, system, molecule, and scaffold; it is not a general synonym for aromatic.
Easily confused with heterocyclic
A carbocyclic ring contains only carbon atoms, whereas a heterocyclic ring contains at least one other kind of atom.
Acyclic describes a molecule or structure with no closed ring, whereas heterocyclic describes a structure that does contain one.