ABSTRACT Two dithienonaphthothiazole derivatives, b ‐DNT and l ‐DNT , were synthesized via photoinduced 6π‐electrocyclization–dehydrogenation of the bithiophene‐substituted benzothiazole 1 . The direct photoirradiation reaction of 1 in the presence of molecular iodine (I 2 ) and propylene oxide preferentially forms b ‐DNT , but under photoinduced electron‐transfer conditions using p ‐chloranil as the photosensitizer, b ‐DNT is generated exclusively. Investigations using nanosecond absorption spectroscopy in conjunction with laser flash photolysis, along with density‐functional theory calculations, led to the identification of potential intermediates in these photochemical processes. X‐ray crystallographic analysis showed that both b ‐DNT and l ‐DNT crystallize in a slipped π‐stacking packing motif. PBEPBE/6‐31G* level calculations suggest that crystals of these substances have large charge‐transfer integrals ( t ) between neighboring molecules that are π‐stacked along the b ‐axis. The t value for l ‐DNT (101 meV) is nearly twofold larger than that for b ‐DNT (54 meV), which is attributed to the existence of more extensive π‐overlap in the former. Based on the Marcus hopping model, theoretical hole mobility along the π‐stacking direction in l ‐DNT is predicted to be as high as 4.0 cm 2 V −1 s − 1 . These results suggest that, owing to their excellent charge transport properties, crystals of b ‐DNT and l ‐DNT have the potential of serving as p‐type organic semiconductors.
Uenaga et al. (2026) studied this question.