1,2,3,4-Tetraphenylnaphthalene is a polyaromatic compounds in which the triplet excited-state of 1,2,3,4-tetraphenylnaphthalene is a primary intermediate of the photochemical transformation of 7,7′-dimethylgerma-1,4,5,6-tetraphenyl-2,3-benzo-norbornadiene (GNB) in hexane solution.