Synthesis and properties of Oligo-6-(2-thienyl)pentafulvenes

Oligomeric and Polymeric Systems with a Cross-conjugated π-Framework

“…Oda and co-workers reported the first examples, 125a-d, incorporating up to four fulvene units (Scheme 34). 96 The oligomers were dark red solids with moderate stability, and UV-vis spectroscopic analysis showed that extending the cross-conjugated framework from 125b (λ max ) 415 nm) to the tetramer 125d (λ max ) 408 nm) had little effect on the HOMO-LUMO energy. The oligomers could be reduced by reaction with 3% Na/Hg, and the dimer 125b and tetramer 125d gave the corresponding di-and tetraanions, respectively, composed of an oligoacetylene spine with pendent cyclopentadienyl anions (125b 2-and 125d 4-, respectively).…”

“…Cross-conjugated oligomers based on a thienyl rather than a phenyl spacer are also known. Oda and co-workers reported the first examples, 125a − d , incorporating up to four fulvene units (Scheme ) . The oligomers were dark red solids with moderate stability, and UV−vis spectroscopic analysis showed that extending the cross-conjugated framework from 125b (λ max = 415 nm) to the tetramer 125d (λ max = 408 nm) had little effect on the HOMO−LUMO energy.…”

Recent Advances in the Chemistry of Pentafulvenes

“…Pentafulvene derivatives have been synthesized to better understand their electrochemical properties. For example, oligo-6-(2-thienyl)­pentafulvenes have been well studied . In this case, the 2-thienyl moiety offers two benefits: (1) electron-donating properties, which stabilize the dipolar structure of pentafulvene, and (2) a convenient site for metalation at the α-position, which provides a site for oligomer extension.…”

“…For example, oligo-6-(2-thienyl)pentafulvenes have been well studied. 465 In this case, the 2-thienyl moiety offers two benefits: (1) electrondonating properties, which stabilize the dipolar structure of pentafulvene, and (2) a convenient site for metalation at the αposition, which provides a site for oligomer extension. Novel donor−π−acceptor chromophores have been developed on the basis of fulvene as an accepting moiety due to its higher polarizability, 17 and 1,3-dithiole-2-ylidene as a donor moiety.…”