6,13-dihydropentacene and pentacene single co-crystals
  6,13-dihydropentacene and pentacene co-crystallise in a ratio of 2:1 during vapour transport of commercial pentacene in a gas flow. The crystal structure is monoclinic P2_1/n and contains one dihydropentacene molecule, and half a pentacene molecule in the asymmetric unit. 
Christine C. Mattheus, Jakob Baas, Auke Meetsma, Jan L. de Boer,   Christian Kloc, Theo Siegrist, and Thomas T.M. Palstra