Synthesis of Tetra(3‐thienyl)biphenoquinone and its Charge Transfer Complex with Perylene

Abstract

Te tra(thienyl)biphenoquinones were designeda nd synthesized. An oxidative coupling of 2,6-bis(3-thienyl)phenol with PbO 2 in acetic acid afforded the corresponding biphenoquinonea long with 2,6-bis(3-thienyl)-p-benzoquinone. This biphenoquinone showed properties characteristic of a p-expanded quinone, that is, positively shifted reduction potential and light absorption in the visible region. In contrast to kinetically protected biphenoquinones with bulky substituents at the ortho-positions of carbonyls, the title compoundst ake ap lanar structure because of the small steric repulsion of the five-membered thiophene rings. Its charge transfer complex with perylenei sc haracterized by aw elloverlapped mixed stack.Scheme1.Structures of aryl-substituted biphenoquinones and related quinones. The chemical shifts of -H a and -H a' for 2, 3, 4,a nd 7 in the 1 HNMR spectra (in CDCl 3 )are discussed in the text.