Gold‐Catalyzed Facile Synthesis and Crystal Structures of Benzene‐/Naphthalene‐Based Bispentalenes as Organic Semiconductors

Abstract

The gold‐catalyzed facile synthesis of U‐shaped and S‐shaped bispentalenes is described from easily available tetra(arylethynyl)‐benzenes and ‐naphthalenes. The optoelectronic and transistor properties were also investigated. The selectivity between the U‐shaped and S‐shaped bispentalene isomers can be tuned by the bulkiness of the ligand and the substrates. The S‐shaped naphthalene‐based bispentalene shows a one‐dimensional face‐to‐face packing pattern in solid state and a good hole mobility, indicating that the S‐shaped bispentalene core is highly suitable for transistor applications. The gold‐catalyzed annulation of tetraynes provides a useful protocol in the synthesis of bispentalenes for organic semiconductors.

Gold‐Catalyzed Regiospecific Annulation of Unsymmetrically Substituted 1,5‐Diynes for the Precise Synthesis of Bispentalenes

“…When the cyclization of 6a was performed using (IPr)AuCl/AgNTf 2 , isomers 7 a and 8 a were produced in a 22:78 ratio. In our previous report, the bulkiness of the ligand had a significant effect on the ratio of the resulting bispentalene isomers. Therefore, a set of differently sized ligands on the catalysts was investigated to prove this effect on the selectivity of isomeric bispentalenes 7 a and 8 a .…”

“…The connectivity of 5 b in the solid state was confirmed by X‐ray crystallography (Figure ). Due to the mesityl group, the previously reported n ‐pentyl substituted S‐shape bispentalene B (Figure ) shows significantly smaller torsion angles (34.2–37.9°) between the pentalene core and the peripheral aryl group than pentalene 5 b (63.5–69.3°).…”

“…The optical properties of bispentalenes 5 a , 5 b , 7 a and 7 b were examined by UV–Vis absorption spectroscopy in dichloromethane (Figure ). Based on previous work, the two characteristic absorptions ( λ =450–550 nm) of 5 a , 7 a , and 7 b might be assigned to HOMO→LUMO+1 and HOMO−1→LUMO transitions. The introduction of mesityl groups has a significant effect on the absorption.…”

“…Our recent work also contributed to the gold‐catalyzed synthesis of dibenzo[ a , e ]pentalene and quinoxaline/phenazine‐fused pentalene derivatives from 1,5‐diynes . Moreover, the gold catalyst led to both U‐shaped and S‐shaped bispentalenes from the readily available tetra(arylethynyl)benzenes and ‐naphthalenes, albeit fortunately those mixtures could be separated (Scheme , top) . During that study, the naphthalene‐based linear bispentalene (S‐shaped) was found to be a highly suitable scaffold for transistor applications.…”

Cations and Anions of Dibenzo[a,e]pentalene and Reduction of a Dibenzo[a,e]pentalenophane

“…[23] The oxidation and reduction products of DBP are also of interest regarding the application of DBPs as semiconductors in organic field-effectt ransistors (OFETs). DBP derivatives and further benzannulated diaceno[a,e]pentalenes have been employed in both p- [24][25][26][27][28][29] and n-type [30] OFET devices. The charge transport is thought to proceed throughe ither the cation radical in the case of p-type doping or the anion radicalf or an ntype device.…”