Synthesis of side-chain regioregular and main-chain alternating poly(bichalcogenophene)s and an ABC-type periodic poly(terchalcogenophene)

• Published in: Chemical science (Cambridge) 2020-03, Vol.11 (15), p.3836-3844
• Main Authors: Liu, Huai-Hsuan, Liang, Wei-Wei, Lai, Yu-Ying, Su, Yen-Chen, Yang, Hau-Ren, Cheng, Kuang-Yi, Huang, Sheng-Cih, Cheng, Yen-Ju
• Format: Article
• Language: English
• Subjects: Bulk density; Catalysts; Chains; Chemistry; Electron density; Metathesis; Nickel; Walking
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d0sc00404a

Three unsymmetrical diiodobichalcogenophenes SSeI 2 , STeI 2 , and SeTeI 2 and a diiodoterchalcogenophene SSeTeI 2 were prepared. Grignard metathesis of SSeI 2 , STeI 2 , SeTeI 2 , and SSeTeI 2 occurred regioselectively at the lighter chalcogenophene site because of its relatively lower electron density and less steric bulk. Nickel-catalyzed Kumada catalyst-transfer polycondensation of these Mg species provided a new class of side-chain regioregular and main-chain AB-type alternating poly(bichalcogenophene)s- PSSe , PSTe , and PSeTe -through a chain-growth mechanism. The ring-walking of the Ni catalyst from the lighter to the heavier chalcogenophene facilitated subsequent oxidative addition, thereby suppressing the possibility of chain-transfer or chain-termination. More significantly, the Ni catalyst could walk over the distance of three rings ( ca. 1 nm)-from a thiophene unit via a selenophene unit to a tellurophene unit-to form PSSeTe , the first ABC-type regioregular and periodic poly(terchalcogenophene) comprising three different types of 3-hexylchalcogenophenes. Three unsymmetrical diiodobichalcogenophenes SSeI 2 , STeI 2 , and SeTeI 2 and a diiodoterchalcogenophene SSeTeI 2 were prepared to synthesize a new class of polychalcogenophenes with precisely controlled sequences by catalyst-transfer polycondensation.