Highly Fluorescent Oligothiophenes through the Incorporation of Central Dithieno[3,2-<i>b</i>:2‘,3‘-<i>d</i>]pyrrole Units

Dithieno[3,2-<i>b</i>:2‘,3‘-<i>d</i>]pyrrole-based terthiophene (<b>2a</b><b>−</b><b>c</b>) and quaterthiophene (<b>3a</b><b>−</b><b>c</b>) analogues have been prepared from dithieno[3,2-<i>b</i>:2‘,3‘-<i>d</i>]pyrrole (<b>1</b>) via Stille coupling utilizing a one-pot method. In comparison to the parent oligothiophenes (T<i><sub>n</sub></i>, where <i>n</i> = 2−4), the resulting dithieno[3,2-<i>b</i>:2‘,3‘-<i>d</i>]pyrrole-based systems exhibit enhanced fluorescence efficiencies in solution (up to 53%). These new oligomeric systems also allow the incorporation of solubilizing side chains without the negative steric interactions that typically reduce backbone planarity.