Direct Arylation Polycondensation of 2,5-Dithienylsilole with a Series of Difluorobenzodiimine-Based Electron Acceptors

• Published in: Macromolecules Vol. 50; no. 12; pp. 4623 - 4628
• Main Authors: Scott, Colleen N, Bisen, Milind D, Stemer, Dominik M, McKinnon, Samuel, Luscombe, Christine K
• Format: Journal Article
• Language: English
• Published: American Chemical Society 27.06.2017
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/acs.macromol.7b00046

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 cross-coupling 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 (<2.0 eV), and P1 provided hole mobility values in the range of 10–2 cm2/(V s), which is superior to previously reported values for 2,5-dithienylsilole-containing polymers (10–4–10–6 cm2/(V s)) and comparable to dithienosilole-containing polymers.