Rhodium-Catalyzed Stitching Polymerization of Alkynylsilylacetylenes

Abstract

Polymers possessing a silicon-bridged π-conjugated repeating unit constitute an important class of compounds for their potential utility as optoelectronic materials. Herein we developed a rhodium-catalyzed stitching polymerization of nonconjugated and readily prepared alkynylsilylacetylenes for the synthesis of new πconjugated polymers with ladder-type silicon-bridged repeating units. The polymerization proceeded smoothly by employing a Rh/ tfb complex as the catalyst, and not only diynes but also triynes and tetraynes could be polymerized in a stitching manner to give polymers that are inaccessible by existing methods. The solubility of the polymers in different types of solvents could be controlled by introducing appropriate functional groups on the silicon atoms, and sequence-controlled functionalized polyacetylenes could be accessed by protodesilylation of the stitched polymers. Physical properties of the obtained polymers were also investigated to understand their characteristic features.

Rhodium-Catalyzed Stitching Reactions for the Facile Synthesis of Extended π-Conjugated Compounds

“…In particular, polymerization in the presence of a combination of [RhCl(tfb)] 2 and Et 3 N in THF at –10 °C gave poly-25a ( M n = 84000) in a nearly quantitative yield (Scheme 16 ). 24 Various monomers having different substituents on the alkyne could be used to give the corresponding stitched polymers with M n values of 23000–46000 (Scheme 16 ). In addition, by introducing appropriate substituents on the silicon atoms, the solubility of the polymers toward regular organic solvents, diluted acidic water, or fluorous solvents could be controlled without changing the π-conjugation structures in the main chain.…”

Cascade Cyclopolymerization of 5‐Ethynyl‐1,8‐Nonadiyne Derivatives to Synthesize Low Band Gap Conjugated Polyacetylenes Containing a Fused Bicyclic Structure

“…[7,8] Nonetheless, this strategy is limited to thiophene [9] -and phenylene [10] -based arene monomers, and few reports have addressed the synthesis of polyacetylene (PA) from alkyne monomers. [11,12] In 2019, Shintani et al reported pioneering works on a novel strategy for Rh-catalyzed stitching polymerization to synthesize conjugated polymers containing a fused bicyclic ring from non-conjugated 1-aryl-1,5hexadiyne monomers. [11] However, the synthetic method showed broad dispersity, and despite the formation of a rigid bridged conjugated structure during polymerization, the effective conjugation length was somewhat shorter than the previous PAs containing the ring in the backbone, thereby increasing the optical band gap to 2.02 eV (Scheme 1a).…”

“…Starting with poly(isothianaphthene) [6] first reported in 1984, various fused ring systems have been introduced to semiconducting materials and widely used in polymer electronics [7, 8] . Nonetheless, this strategy is limited to thiophene [9] ‐ and phenylene [10] ‐based arene monomers, and few reports have addressed the synthesis of polyacetylene (PA) from alkyne monomers [11, 12] . In 2019, Shintani et al.…”

Synthesis of Poly(arylenevinylene)s by Rhodium-Catalyzed Stitching Polymerization/Alkene Isomerization

“…On the other hand, we recently developed a rhodium-catalyzed stitching polymerization as a new method to synthesize π-conjugated polymers possessing a ladder-type repeating unit (Scheme a) . In this polymerization, readily accessible non-conjugated oligo­(alkyne)­s were used as monomers, and construction of bridged π-conjugated repeating units and chain propagation were achieved at the same time through inter- and intramolecular multiple alkyne insertion processes under rhodium catalysis.…”