Heteroheptacenes with Fused Thiophene and Pyrrole Rings

Abstract

The preparation of conjugated heteroheptacenes using an electrophilic coupling reaction induced by a super acid is reported. The new molecules containing thiophene and/or pyrrole rings are bisbenzo[b,b']thienodithieno[3,2-b:2',3'-d]pyrrole, bisbenzo[b,b']thienocyclopenta[2,1-b:3,4-b']dithiophene, and bisthieno[3,2-b]thieno[2,3-f:5,4-f']carbazole. Dithieno[3,2-b:2',3'-d]pyrrole, cyclopenta[2,1-b:3,4-b']dithiophene, and carbazole are used as the aromatic cores. This versatility provides access to molecules with systematically controllable physicochemical properties. Single-crystal X-ray analyses demonstrate that the type and position of the alkyl substituents significantly changes the packing properties of the new molecules. The optical and optoelectronic properties of the heteroheptacenes vary considerably depending on the number and position of the sulfur or nitrogen linkages and reveal the improved environmental stability over their hydrocarbon counterparts. The analysis of the experimental results from UV/Vis absorption/photoluminescence (PL) spectroscopy and cyclic voltammetry were combined with DFT quantum-chemical calculations and compared with other model heteroheptacenes. The results suggest that among the acenes with the same number of fused rings, the thiophene ring fusion inside the skeleton stabilizes both HOMO and LUMO levels more effectively than pyrrole and benzene rings. The present study also shows that the new heteroheptacenes are promising candidates for the construction of electronic materials.

Tuning the Optoelectronic Properties of Nonfullerene Electron Acceptors

“…After tetrakis(triphenylphosphine)palladium(0) (4.5 mg, 0.004 mmol) was added, the mixture was deoxygenated af urther five times, and then heated at reflux for 20 h. After cooling to room temperature, the organic layer was separated and the aqueous layer was extracted with dichloromethane (3 5mL). [1,2,5]thiadiazol-4-yl)methylene]malononitrile (10) [18] Am ixture of 9 (450 mg, 1.0 mmol), malononitrile (1.3 g, 20 mmol) and pyridine (0.5 mL) in anhydrous toluene (20 mL) was deoxygenated five times by placing under vacuum (100 mBar) and backfilling with argon, and then heated at 70 8Cf or 16 h. After cooling to room temperature, the solvent was removed and the residue was purified by column chromatography over silica with ad ichloromethane/n-hexane mixture ( [22] (380 mg, 1.44 mmol) in anhydrous tet-rahydrofuran (40 mL) that had been cooled in an acetone/dry ice bath under argon. The solvent was removed under reduced pressure and the residue was purified by column chromatography over silica using ad ichloromethane/nhexane (80:2 0) mixture as the eluent to give 5 as an orange gum (45 mg, 78 %).…”

Self-assembly and charge transport properties of a benzobisthiazole end-capped with dihexyl thienothiophene units

“…17 This strategy avoids trap states 18 that are often seen with pentacene and related materials, leading to instability in air. There has been interest lately in conjugated materials incorporating electron-deficient heterocycles, such as [1,3,4]thiadiazoles [19][20][21][22][23] and dibromobenzo [1,2-…”

“…[1][2][3][4][5][6][7] Increased planarity and rigidity in such structures lead to better p-orbital overlap and a lower HOMO-LUMO gap, whilst the two-dimensional (i.e. flat) nature of the materials leads to efficient p-p stacking between molecules.…”

Thienoacene‐Based Organic Semiconductors

“…The effectiveness of this chemistry was also proven by performing the synthesis of related heteroheptacenes with fused thiophene and pyrrole rings. [ 46 ] Alternative methods for the syntheses of 2a and its selenium analogue ( 2c ) via the consecutive double cyclization approach were also reported ( Scheme 4 ). [ 12 ] Readily available reaction was developed by Müllen and co-workers, which involved the intramolecular coupling reaction of aromatic methyl sulfoxides with an activated aromatic building block in the presence of strong acids (Scheme 2 b).…”