Effect of catalyst isospecificity on the structure of poly(phenylacetylene) with Ziegler‐Natta catalysts

Deuterium Nuclear Quadrupole Coupling and cis−trans Isomerization in Poly(phenylacetylene-d1)

“…The thermal isomerization of the polyene chain is of interest because the change from the cis form to the trans form affects molecular properties such as conductivity, second harmonic generation, and magnetism. − All of these physical properties are closely related to the electronic states of the polyacetylene backbone. There have been many X-ray, IR, and NMR reports on the chain structure and the cis − trans isomerization of substituted polyacetylene polymerized using the various catalysts. − In the case of NMR measurements, the thermal isomerization gave rise to an anomalous spectra in which the high-resolution 13 C and 1 H NMR signals of the main chain become broader with the decrease of the resonance intensity. ,− Nevertheless, it is believed that the main chain structure would be the trans -transoidal when the isomerization occurred, but no experimental evidence has been confirmed. In order to clarify the relationship between the broadening of the NMR spectrum and the isomerization, therefore, it is important to determine, from experiment and theory, the cis and trans forms of the main chain.…”

“…[4][5][6][7] In the case of NMR measurements, the thermal isomerization gave rise to an anomalous spectra in which the high-resolution 13 C and 1 H NMR signals of the main chain become broader with the decrease of the resonance intensity. 5,[7][8][9][10][11][12][13] Nevertheless, it is believed that the main chain structure would be the transtransoidal when the isomerization occurred, but no experimental evidence has been confirmed. In order to clarify the relationship between the broadening of the NMR spectrum and the isomerization, therefore, it is important to determine, from experiment and theory, the cis and trans forms of the main chain.…”

Precursor route to ethenyl-substituted polyacetylenes: synthesis of homopolymers of o-trimethylsilyl-ethers of 1-alkyl and 1-aryl substituted but-3-yn-1-ols. Desilylation, dehydration and pyrolysis to conducting films

“…Sharp ~3C signals at 34.2 and 129.9 ppm were assigned to small amounts of trimer. The broad signal of the vinylic region clearly indicates atactic microstructures for all polymers [17,18]. Fr-IR spectroscopy (KBr pellets) proved the absence of carbonylic impurities (1705 cm -1) [17].…”

Helical chirality of π‐conjugated main‐chain induced by polymerization of phenylacetylene with chiral bulky pinanyl groups: Effects of the flexible spacer and polymerization catalyst

“…The cis % of the configuration of the double bonds in the main chain was determined by the ratio of the intensity of the peak at δ 5.8, 6.6, and 7.7 ppm in 1 H NMR spectra 20. In addition, polyacetylenes can have four types of backbone configurations: cis‐transoidal (c‐t), cis‐cisoidal (c‐c), trans‐transoidal (t‐t), and trans‐cisoidal (t‐c) 21.…”