Semiconducting Polymers via Microwave-Assisted Suzuki and Stille Cross-Coupling Reactions

• Published in: Advanced functional materials Vol. 14; no. 4; pp. 352 - 356
• Main Authors: Nehls, B. S., Asawapirom, U., Füldner, S., Preis, E., Farrell, T., Scherf, U.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.04.2004; WILEY‐VCH Verlag
• Subjects: Microwave-assisted synthesis; Semiconducting polymers; Suzuki coupling
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.200400010

A fully conjugated para‐phenylene ladder polymer (P1) and the alternating copolymers {2,7‐[9,9‐bis(2‐ethylhexyl)fluorene]‐5,5′‐(2,2′‐bithiophene)} (P3) and {2,7‐[9,9‐dioctylfluorene]‐5,5′‐(2,2′‐bithiophene)} (P4) have been prepared via metal‐mediated cross‐coupling reactions, using microwaves as a heat source. The procedure, which yields polymeric material in ca. ten minutes, has no adverse effects on the quality of the polymers and displays a high degree of reproducibility. Transfer of the optimized conditions to the synthesis of a new naphthalene‐based polyarylene‐ketone (P2) and a (1,5‐dioctoxynaphthylene‐2,6‐diyl‐alt‐2,2′‐bithiophene‐5,5′‐diyl) copolymer (P5) confirmed the versatility of the procedure and the dramatic reduction in reaction times compared with conventional heating. In the case of the Stille‐type coupling reaction of the electron‐rich, less reactive dibromo monomer 1,5‐dioctoxy‐2,6‐dibromo‐naphthalene, the microwave‐assisted protocol results in a marked increase in both yield and molecular weight. Microwave‐assisted protocols developed for the preparation of semiconducting polymers, in dramatically reduced reaction times and, in some cases, better yields and molecular weights, are reported. Synthesis is achieved via palladium‐mediated Suzuki‐ and Stille‐type reactions.