Phenanthrene

Phenanthrene is a polycyclic aromatic hydrocarbon composed of three fused benzene rings. The name phenanthrene is a composite of phenyl and anthracene. In its pure form, it is found in cigarette smoke and is a known irritant, photosensitizing skin to light.] Phenanthrene appears as a white powder having blue fluorescence.
The compound with a phenanthrene skeleton and nitrogens at the 4 and 5 positions is known as phenanthroline.
Phenanthrene is the backbone of morphinan, which in turn is the backbone of a large number of psychoactive chemicals including antitussives, analgesics, and dissociative drugs.