Cofacially constrained organic semiconductors

We present the synthesis, spectroscopy, and electrochemistry of bis[oligo(thiophene)] monomers where the sterics of covalently attached subunits enforced oblique spatial orientations. The synthetic scheme applied to a variety of chromophores; standard bromination and cross-coupling chemistry afforded bis(terthienyl)benzene systems in high yield. We prepared model systems consisting of mono(terthiophene)s to probe the effects that van der Waals contacts impose during electropolymerization. and methyl-blocked analogues to examine the electrochemical properties of derivatives that do not undergo polymerization. We discuss the extent of delocalization between chromophores as deduced from electrochemical studies and demonstrate that these materials provide viable electrochromic polymers. (C) 2003 Wiley Periodicals, Inc.