Construction of rod-like diketopyrrolopyrrole oligomers with well-defined length

Oligomers of well-defined length were prepared by a stepwise sequence of Suzuki couplings using brominated 1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DPP) derivatives and 1,4-dibromo-2,5-di-n-hexylbenzene as the monomers. The resulting oligomers contained three, five and seven DPP units, respectively, and could be characterized by 1H NMR spectroscopy. These compounds could be of potential use as new electroluminescent materials.