Terpyridine (2,2';6',2"-terpyridine, often abbreviated to Terpy or Tpy) is a heterocyclic compound derived from pyridine.

[3] The base-catalyzed reaction of 2-acetylpyridine with carbon disulfide followed by alkylation with methyl iodide gives C5H4NCOCH=C(SMe)2.

Terpyridine is a tridentate ligand that binds metals at three meridional sites giving two adjacent 5-membered MN2C2 chelate rings.

Terpyridine complexes, like other polypyridine complexes, exhibit characteristic optical and electrochemical properties: metal-to-ligand charge transfer (MLCT) in the visible region, reversible reduction and oxidation, and fairly intense luminescence.

Because they are pi-acceptors, terpyridine and bipyridine tend to stabilize metals in lower oxidation states.