Silicon Promoted Cationic Polymerization of Phenylacetylenes

Abstract

Poly(phenylacetylene)s (PPAs) are widely applied in a variety of research fields due to their good electrical and optical properties. Transition-metal-catalyzed polymerizations are generally performed for the synthesis of PPAs, while the residual metal catalysts might be problematic. In this work, we present a silicon promoted cationic polymerization of phenylacetylenes (PAs) by introducing a labile and electrondonating silyl group at the alkynyl termini of PA monomers. The polymerizations were performed in the presence of trifluoromethanesulfonic acid to rapidly produce the PPA products with good yields. The structures of the PPAs were characterized by NMR, IR, MALDI-TOF MS, UV−vis, and fluorescence spectroscopies, showing that the PPAs consist of conjugated skeletons with high contents of trans-configurations. GPC analysis showed a relatively narrow molecular weight distribution, and the molecular weight reached up to 4.7 kDa. A possible reaction scheme was proposed through further analysis on the structures of three kinds of oligomeric species. As the silyl groups are generally inherited from Sonogashira coupling reactions during the synthesis of PAs, this work presents a straightforward and metal-free method for the synthesis of PPAs.

Synthesis of Conjugated Mesoporous Hyper-cross-linked Polymers for Efficient Capture of Dibenzothiophene and Iodine

“…The elemental analysis of CMHPs-5 is shown in Table S2. The total content of C and H is 77.8%, while the trace amount of sulfur element might come from the terminal triflate groups in SPCP . The remaining contents can be attributed to the adsorbed water and oxygen in the pores, which is consistent with the results of FT-IR and TGA.…”

“…The stretching vibration peaks of the carbon–carbon triple bonds in the monomers near 2150 cm –1 almost disappear in their corresponding CMHPs, confirming the polymerization of the alkynyl groups. The vibrational bands of the double bonds (around 1600 cm –1 ) including those in the aromatic rings and the main chain of polymers resemble the ones in polyphenylacetylenes reported in our previous work, suggesting the formation of the extended π-conjugated structure after polymerization.…”

“…The multialkynyl arene monomers (M1–M5) were readily synthesized through the Sonogashira coupling reaction between TMS acetylene and aromatic bromides in high yields (Supporting Information). As demonstrated in our early work, the TMS group at the alkyne terminal was the key for this SPCP strategy, enabling the fast formation of polyphenylacetylene with high trans-selectivity. Using this new polymerization method, the treatment of M1–M5 with trifluoromethane sulfonic acid gave the corresponding CMHPs (Scheme ) in high yields (Supporting Information).…”

“…The former has excellent chemical stability, while the latter has rich π electrons. Herein, we report the synthesis of a variety of conjugated mesoporous HCPs (CMHPs) by our newly developed silicon-promoted cationic polymerization (SPCP) strategy, which features metal-free polymerization of aromatic alkynes and avoids the use of expensive transition-metal catalysts and the negative effects of the residual catalysts. The introduction of the electron-donating trimethylsilyl (TMS) group at the alkynyl end significantly improves the chain extension ability of the cationic reaction intermediate to give polyphenylacetylene with much higher molecular weight.…”

Room-temperature Barbier single-atom polymerization induced emission as a versatile approach for the utilization of monofunctional carboxylic acid resources

“…2,3,[37][38][39][40][41] Accompanied by the developments of different polymerization methods, different chemical moieties, including dicarboxylic acids, diols, diamines, alkenes, alkynes, thiols, etc., have been successfully developed as building blocks of polymer materials. [42][43][44][45][46][47] The variety and availability of monomers are important factors for evaluating polymerization methods. Carboxylic acid containing compounds are widely available chemicals from both biomass and fossil sources on the Earth, and have been comprehensively used in organic synthesis for centuries.…”