Direct Arylation Polycondensation of 2,5-Dithienylsilole with a Series

Jun 9, 2017 - This result demonstrates the power of the DArP method to prepare ... These low LUMO energies result from the overlap between the σ* orb...
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Article pubs.acs.org/Macromolecules

Direct Arylation Polycondensation of 2,5-Dithienylsilole with a Series of Difluorobenzodiimine-Based Electron Acceptors Colleen N. Scott,*,† Milind D. Bisen,‡ Dominik M. Stemer,§ Samuel McKinnon,† and Christine K. Luscombe§ †

Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39769, United States Department of Chemistry and Biochemistry, Southern Illinois University Carbondale, Carbondale, Illinois 62901, United States § Materials Science and Engineering Department, University of Washington, Seattle, Washington 98195, United States ‡

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ABSTRACT: This paper describes the use of direct arylation polymerization (DArP) reaction to synthesize three new 2,5-dithienylsilole polymers with a series of difluorobenzodiimine-based electron acceptors: 5,6-difluoro[2,1,3]benzothiadiazole (DFBT), 5,6-difluoro[2,1,3]benzoselenadiazole (DFBSe), and 5,6-difluoro[2,1,3]benzotriazole (DFBTA). The Stille crosscoupling polycondensation reaction was performed to confirm the structural quality of the polymers; however, only low molecular weight oligomers were obtained. This result demonstrates the power of the DArP method to prepare polymers containing strong electron-deficient monomers. During our investigation, it was found that Fagnou’s condition did not produce polymers, whereas the condition reported by Ozawa and co-workers gave polymers with moderate molecular weights. This is the first known example of the synthesis of 2,5-dithienylsilole-containing polymers by the DArP. Our polymers have reduced band gaps (