Radiation-induced Cis to Trans isomerization of poly(n-butylpropiolate) prepared with a [Rh(norbornadiene)Cl]2 complex as a stereospecific catalyst

Kozuka, Munehiro; Sone, Toshio; Tabata, Masayoshi; Sadahiro, Yoshikazu; Enoto, Takeaki

doi:10.1016/s0969-806x(01)00482-0

Cited by 15 publications

(7 citation statements)

References 7 publications

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“…Hexagonal packing was interestingly found to make polyvinylenes, mainly poly(propiolic ester)s, more resistant to autoxidative degradation 112,113 . The macromolecules assembled in columnar nanostructures were found to undergo the cis-to-trans isomerization when exposed to high pressure 73,95,110,114,115 , UV or γ irradiation 116,117 . The radical mechanism has been proposed for this isomerization.…”

Section: Helical Polyvinylenes Columnar Structuresmentioning

confidence: 99%

Controlled and Living Polymerizations Induced with Rhodium Catalysts. A Review

Sedláček¹,

Vohlı́dal²

2003

Collect. Czech. Chem. Commun.

101

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In the last fifteen years, a large variety of specialty polymers of diverse chemical structure and functionality have been synthesized with the rhodium-based catalysts. The high tolerance to the reaction medium and functional groups of monomers, as well as ability to control various structure features of the polymer formed are typical properties of these catalysts. In addition, some rhodium catalysts can be anchored to inorganic or organic supports or dissolved in ionic liquids to form heterophase polymerization systems, which opens the way to pure, well-defined polymers free of the catalyst residues, as well as to recycling rhodium catalysts. This review provides a survey on the polymerization reactions induced with rhodium-based catalysts, in which one or more structure attributes of the polymer formed are subject to control. The structure attributes considered are (i) sequential arrangement of monomeric units along polymer chains; (ii) head-tail isomerism of polymer molecules; (iii) configurational structure of polymer molecules; (iv) conformation of polymer molecules; and (v) molecular weight and molecular-weight distribution of the polymer formed. A review with 188 references.

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Section: Helical Polyvinylenes Columnar Structuresmentioning

confidence: 99%

Controlled and Living Polymerizations Induced with Rhodium Catalysts. A Review

Sedláček¹,

Vohlı́dal²

2003

Collect. Czech. Chem. Commun.

101

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“…The former factor influences the length of π-conjugation in the main chain, e.g., substituted polyacetylenes prepared using the Rh-complex-based catalyst are normally yellow, having a cis-transoidal ( ct ) main chain with relatively short-range π-conjugation (over two or three monomer units) [42]. In the case when the main chain contains the trans-transoidal ( tt ) isomer (e.g., as a result of cis -to- trans isomerization induced by external stimuli such as pressure [29,30,31], UV irradiation [32,33], and heat treatment [28]), the corresponding polymers tend to be brown, red, or black, since the π-conjugation of the tt isomer is more extended than that of the ct isomer. Therefore, the main chain of the yellow polymers described herein (poly( 1 ), poly( 3 ), poly( 4 ), poly( 5 ), and poly( 6 )) was concluded to exhibit ct geometry.…”

Section: Resultsmentioning

confidence: 99%

“…PPAs form helical structures only when their main chain has a cis -configuration. However, the cis -to- trans isomerization is easily induced by external stimuli such as heat treatment [28], compression [29,30,31], and irradiation [32,33], which is accompanied by the collapse of the helical structure. Therefore, practical applications of helical molecules necessitate the development of robust helical structures.…”

Section: Introductionmentioning

confidence: 99%

Methoxy-Group Control of Helical Pitch in Stereoregular Poly(2-ethynylmethoxynaphthalene) Prepared by Rhodium Complex Catalyst

Mawatari

Yoshida

Huang³

et al. 2019

Polymers

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The position of the methoxy group in a poly(n-methoxy-2-ethynylnaphthalene) (PnMeO2EN) was found to control the helical pitch of the π-conjugated polymer in the solid state. These PnMeO2ENs were stereoregularly synthesized using an Rh-complex catalyst in ethanol or toluene as the solvent. The helical structure in the solid phase was confirmed by conventional analytical methods, namely diffuse reflective ultraviolet–visible light (UV–Vis) and Raman spectroscopies, X-ray diffraction, and 13C cross-polarization magic angle spinning NMR spectroscopy, together with molecular mechanics calculations, because the as obtained polymers were insoluble in common solvents. The color of poly(6-methoxy-2-ethynylnaphthalene) (P6MeO2EN) (yellow or red) depended on the polymerization solvent, whereas no such dependency was observed for the yellow-colored P7MeO2EN and P8MeO2EN. The helical structures energetically optimized by molecular mechanics indicate that the red- and yellow-colored P6MeO2ENs form contracted and stretched helices, respectively. Due to the relatively unconstrained rotations of the 6-methoxynaphthyl moieties, the methoxy groups in P6MeO2EN are less sterically hindered along the helical axis. On the contrary, P7MeO2EN and P8MeO2EN have stretched helices due to the considerable steric hindrance imparted by their methoxy groups. The thermal cis-to-trans isomerization of P6MeO2EN in the contracted-helix form required a somewhat higher temperature than that of the stretched helix.

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“…16 In addition, the colors can be controlled after polymerization by external stimuli such as temperature, pressure, and γ-ray irradiation. 15,[17][18][19] Another important feature of HSPAs is that they contain so-called π-conjugated cis and trans radicals gene-rated through the rotational scission of the cis CvC bond in the main chain when the polymers are subjected to compression 18,[20][21][22][23] or thermal treatment, 20,22,23 or even during polymerization 24 or on keeping the polymer solution at room temperature 25,26 (Scheme 1). Note that the two radicals are completely different from ordinary cation radicals because they were not generated by chemical doping.…”

Section: Introductionmentioning

confidence: 99%