Two new cases of polymorphism in diagonally substituted rubrene derivatives.

The crystal structures of two rubrene derivatives, 5,11-diphenyl-6,12-bis-[4-(tri-fluoro-meth-yl)phen-yl]tetra-cene, C 44 H 26 F 6 , and 5,11-bis-(4- tert -butyl-phen-yl)-6,12-di-phenyl-tetra-cene, C 50 H 44 , are presented. Each are substituted on diagonal (5/11) phenyl rings. Each derivative has one polymorph reported previously. A discussion of the differences between each derivative and its previously reported polymorph is provided. The triclinic packing of the CF 3 -substituted structure is similar to the packing of the parent rubrene's triclinic polymorph. In the tert -butyl-substituted structure, a planar tetra-cene core formed, which has been hypothesized but never published. Crystallization conditions are provided as they differ from previous reports.