1983
DOI: 10.1021/ma00245a001
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Helical configuration of poly(iminomethylenes). Synthesis and CD spectra of polymers derived from optically active isocyanides

Abstract: Each of nine chiral isocyanides, R*-N=C, in enantiomerically pure or almost pure form, is polymerized to the corresponding poly(iminomethylene), [R*-N=C<]n. The group R* either contains at least one substituent (carboxylic ester, phenyl, phosphinyl) or is unsaturated (C=C, C=C). The polymers are of the rigid-rod type with a helical main chain of carbon atoms. Because of the chirality of R*-N=C either the P or the M helix is preferentially formed. CD spectra and optical rotation at 578 nm are determined and com… Show more

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Cited by 62 publications
(41 citation statements)
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“…This kind of reasoning has been applied to approximately 20 optically active monomers. 13 In most cases the predicted helix sense was found to be in agreement with the helix sense derived from optical rotation data and circular dichroism spectra. From this result one may conclude that the process of helix selection takes place at the catalytic centre.…”
Section: Chiral Isocyanidessupporting
confidence: 68%
“…This kind of reasoning has been applied to approximately 20 optically active monomers. 13 In most cases the predicted helix sense was found to be in agreement with the helix sense derived from optical rotation data and circular dichroism spectra. From this result one may conclude that the process of helix selection takes place at the catalytic centre.…”
Section: Chiral Isocyanidessupporting
confidence: 68%
“…In the case of the longer spacers the induction is also increased, and CD measurements show that, surprisingly, for the spacer with a biphenyl unit and one benzoate group (15) the optical activity of the polymer is of the same magnitude but opposite sign to that with two benzoate moieties (16) (Fig. 6).…”
Section: Spacer Effects In Chiral Inductionmentioning
confidence: 95%
“…The slow equilibration of conformations of a nonsterically encumbered aromatic poly (isocyanide) has been observed experimentally, and was interpreted as a slow interconversion as an asformed 4 1 helix to a more open s-trans zigzag conformation which can adopt a helical twist along its length. 15 The stereoselectivity of the polymerization reactions leading to the formation of poly(isocyanide)s as well as their chiroptical properties have been studied in some detail, 16,17 generally with monomers in which the stereogenic center is the carbon atom connected to-or in close proximity to-the nitrogen atom of the isocyanide group. The backbone conformation is determined largely by steric interactions, in polymerizations operating under predominantly kinetic control.…”
Section: Introductionmentioning
confidence: 99%
“…The O-formyl group was selectively removed by heating in aqueous m ethanol (1:1 v/v) at 65 °C for 10 h [18]. The resulting com pound was acetylated with excess acetic anhydride and a catalytic am ount of pyridine [18].…”
Section: N-formyl-o-acetyl-l-tyrosine M Ethyl Estermentioning
confidence: 99%