Résumé : A series of five new hexaalkylthiohexaazatriphenylenes 2a-e has been synthesized. Their thermotropic behaviour has been investigated and compared with the corresponding series of hexaalkylthiotriphenylenes 1a-e and hexaalkylthiohexaazatrinaphthylenes 3a-e. Unexpectedly, hexaalkylthiohexaazatriphenylenes 2a-e, hexaalkylthiotriphenylenes 1d-e and hexaalkylthiohexaazatrinaphthylenes 3e, do not form columnar liquid crystalline mesophases.