Benzo[ a][1,4]benzothia-zino[3,2- c]phenothia-zine

Abstract

The title compound, C₂₂H₁₂N₂S₂, crystallizes in space group P2₁/c with four mol-ecules in the asymmetric unit. The heterocyclic mol-ecule is quasi-planar with a dihedral angle between the phenyl rings on the periphery of the mol-ecule of 1.73 (19)°. Short H⋯S (2.92 Å) and C-H⋯π [2.836 (3) Å] contacts are observed in the crystal with shorted π-π stacking distances of 3.438 (3) Å along the b axis. Surprisingly, and unlike a closely related material, this mol-ecule readily forms large crystals by sublimation and by slow evaporation from di-chloro-methane. The maximum absorbance in the UV-Vis spectrum is at 533 nm. Emission was measured upon excitation at 533 nm with a fluorescence λ_max of 658 nm and cutoff of 900 nm.

Keywords: crystal structure; donor/acceptor; dyes; fused heterocyclic aromatics; ladder oligomers; organic semiconductors.

Figure 1

Structure of title compound with 50% probability ellipsoids.

Figure 2

Packing of molecules governed by π-stacking and C—H⋯π contacts (H13⋯C13).

Figure 3

Uv–vis spectrum of the title compound in DMF.

Figure 4

Emission spectrum of the title compound excited at 533 nm in DMF.