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.