Crystal structure of 6-(p-tolyl) benzo[b]naphtho[2,3-d]thiophene and of an orthorhombic polymorph of 7-phenylanthra[2,3-b]benzo[d]thiophene

The title compounds, C23H16S, (I), and C26H16S, (II), are benzothiophene derivatives in which the benzothiophene moiety is fused with a naphthalene ring system in (I), and with an anthracene ring system in (II). In (I), the mean plane of the benzothiophene ring system makes a dihedral angle of 2.28 (6)degrees with the naphthalene ring system, and a dihedral angle of 1.28 (6)degrees with the anthracene ring system in (II), showing that the fused units are essentially planar. In (I), the 4-methylbenzene ring substituent makes a dihedral angle of 71.40 (9)degrees with the naphthalene ring system, while the phenyl ring substituent in (II) makes a dihedral angle of 67.08 (12)degrees with the anthracene ring system. In the crystals of both compounds, molecules are linked by C-H center dot center dot center dot pi interactions, leading to the formation of slabs parallel to (001) in (I) and to zigzag chains along [001] in (II). There are also offset pi-pi interactions present within the slabs in (I). In the crystal of (II), they link the chains, forming sheets parallel to (010). The triclinic polymorph of compound (II) has been reported [Sivasakthikumaran et al., (2012). J. Org. Chem. 77, 9053-9071].