Accessing π‐expanded heterocyclics beyond dibenzothiophene: Syntheses and properties of phenanthrothiophenes

Abstract

A series of phenanthrothiophenes are designed and synthesized from polyarylthiophenes through regioselective Scholl reactions in one step using iron chloride as catalyst. The molecular structures of these heteroarenes displayed multiple twisted fjords, which perturb the shapes of the polycyclic frameworks to pack in slipped to near‐perfect face‐to‐face styles in parallel or antiparallel packings. Field‐effect transistor devices using single crystals of 6,12‐difluorodiphenanthro[9, 10‐b:9′, 10′]thiophene gave a hole mobility of 0.22 cm2 V−1 s−1.

Steering Scholl Oxidative Heterocoupling by Tuning Topology and Electronics for Building Thiananographenes and Their Functional N−/C−Congeners

“…[20][21][22] Particularly, tetraarylthiophenes (TATs) giving thiananographenes can be cited (Figure 1b). [4,23,24] Examples with TATs highlight CÀ C bond formation between two aryl units substituted at the thiophene αand β-positions (Figure 1b). However, a pressing concern is that SOC is sensitive to the substrate design (topology), [25][26][27] electronics of the cyclizing aryl partners, [28][29][30][31][32] reagents, and reaction conditions.…”

“…Most reports have bypassed this by introducing blocking groups (R) or by choosing annulated aryl units at the reactive sites (Figure 1b). [4,23] Another route to construct thiananographenes is by successfully establishing the CÀ C bond intramolecularly between the thiophene (α-/β-positions) and cyclizing arene under Scholl oxidative conditions (Figure 1c). [6,12,[33][34][35] This heretoforeunprecedented approach is challenging, especially due to the competing high reactivity of thiophene's (α-or β-) positions towards oxidative polymerization over thiophene-arene heterocoupling.…”

“…The latter approach explores Scholl oxidative cyclization (SOC), [16–19] besides transition‐metal based annulation methods [20–22] . Particularly, tetraarylthiophenes (TATs) giving thiananographenes can be cited (Figure 1b) [4,23,24] . Examples with TATs highlight C−C bond formation between two aryl units substituted at the thiophene α‐ and β‐positions (Figure 1b).…”

“…As evidenced, tetraphenylthiophene (TPT) under oxidative conditions failed to yield simple diphenanthro[9,10‐ b :9′,10′‐ d ]thiophene (DPT), [4,23,24] a simple thiananographene. Most reports have bypassed this by introducing blocking groups (R) or by choosing annulated aryl units at the reactive sites (Figure 1b) [4,23] …”

“…However, a pressing concern is that SOC is sensitive to the substrate design (topology), [25][26][27] electronics of the cyclizing aryl partners, [28][29][30][31][32] reagents, and reaction conditions. [16,17] As evidenced, tetraphenylthiophene (TPT) under oxidative conditions failed to yield simple diphenanthro[9,10b:9',10'-d]thiophene (DPT), [4,23,24] a simple thiananographene. Most reports have bypassed this by introducing blocking groups (R) or by choosing annulated aryl units at the reactive sites (Figure 1b).…”