4,4′-Dipyridyl-d8 is the deuterium labeled 4,4'-Dipyridyl. 4,4′-Dipyridyl is a heterocyclic compound. 4,4′-Dipyridyl is utilized as an electronic and photosensitive building block and bidentate ligand in supramolecular chemistry. 4,4′-Dipyridyl can also be used as a drug intermediate in the synthesis of paraquat, a widely used herbicide.