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π‐Extended Pentalenes: The Revival of the Old Compound from New Standpoints
Author(s) -
Kawase Takeshi,
Nishida Junichi
Publication year - 2015
Publication title -
the chemical record
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.61
H-Index - 78
eISSN - 1528-0691
pISSN - 1527-8999
DOI - 10.1002/tcr.201402093
Subject(s) - pentalene , derivative (finance) , conjugated system , ring (chemistry) , organic semiconductor , heterojunction , combinatorial chemistry , materials science , organic electronics , chemistry , computational chemistry , nanotechnology , organic chemistry , molecule , optoelectronics , polymer , transistor , physics , quantum mechanics , voltage , financial economics , economics
Polycyclic conjugated systems bearing carbocyclic five‐membered rings have attracted much attention due to their novel electronic properties and utility in organic electronic devices. Despite possessing a 4 n π electron periphery, dibenzopentalenes have a planar structure and are fairly stable. Thus, appropriate modifications should provide desirable electronic properties. Recently, we have discovered novel N i‐catalyzed coupling reactions that constitute a versatile new route to dibenzopentalene derivatives from readily available o ‐bromoethynylbenzenes. Moreover, we developed another dibenzopentalene synthesis using indenone derivatives as important intermediates. These methods are applicable to π‐extended pentalene derivatives possessing various functional groups and aromatic ring systems. Among them, a dinaphthylpentalene derivative shows a high hole mobility (1.8 × 10 −3 cm 2 V −1 s −1 ) for an amorphous material. Furthermore, this is the first pentalene derivative that can be employed as a p‐type material for organic heterojunction photovoltaic cells ( PCE = 0.94%, V OC = 0.96 V ) and as organic thin‐film semiconductors.