Macromolecular stereochemistry: Effect of pendant group structure on the conformational properties of polyisocyanides

Mark M. Green, Richard A. Gross, Frederic C. Schilling, Karl Zero, Charles Crosby

Research output: Contribution to journalArticle

Abstract

The hydroxyl function of the S enantiomer of the 1,2-acetone ketal of propylene glycol was converted, via the amine, to the isocyanide ([α]546 +32.9° (CHCl3)), which was polymerized by using NiCl2 hexahydrate in the neat state to the derived poly((S)-2,2-dimethyl-1,3-dioxolane-4-methyl isocyanide) ([α]546 +68.5° (p-dioxane); Mw = 165 000). The ultraviolet spectrum of this brown solid in CHCl3 exhibited a band, as a shoulder on lower wavelength absorptions, with λmax = 295 nm and 3.2 × 102 L mol-1 cm-1, and a long low-intensity visible region tail. The circular dichroism (CD) spectrum was similar to published spectra for α-substituted asymmetric polyisocyanides and showed three maxima (λmax, nm; Δ∈, L mol-1 cm-1): 328, -0.082; 290, +0.015; 275, -0.047. High-field 13C NMR studies exhibited extensive chemical shift dispersion for both the backbone carbon and the pendant carbons. Similar shift dispersion was encountered in poly(n-butyl isocyanide) and in poly(benzyl isocyanide). Poly((R)-α-phenylethyl isocyanide) also exhibited chemical shift dispersion superimposed on symmetrical but broadened lines in its 13C NMR spectrum. Zimm plots constructed from wide-angle 633-nm light scattering data on poly((R)-α-phenylethyl isocyanide) (Mw = 107 000) and on poly((5)-2,2-dimethyl-1,3-dioxolane-4-methyl isocyanide) (Mw = 165 000) showed no angular dependence. The weight average hydrodynamic radii of these polymers in tetrahydrofuran were determined by photon correlation spectroscopy to be 51 and 24 Å, respectively. If one adopts a 4/1 helix with a pitch of 4 Å proposed in the literature for poly(α-phenylethyl isocyanide), our data yield a persistence length of 32 Å, which is substantially larger than that for poly((S)-2,2-dimethyl-1,3-dioxolane-4-methyl isocyanide). The results show that some form of stereoirregularity, which could involve syn-anti isomerism about the carbon-nitrogen double bond, is seen in each of the polymers studied. In addition, the chain dimension is strongly dependent on the pendant group structure.

Original languageEnglish (US)
Pages (from-to)1839-1846
Number of pages8
JournalMacromolecules
Volume21
Issue number6
StatePublished - 1988

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Stereochemistry
Cyanides
Chemical shift
Carbon
Nuclear magnetic resonance
Photon correlation spectroscopy
Enantiomers
Dichroism
Polymers
Glycols
Acetone
Light scattering
Propylene
Amines
Hydrodynamics
Propylene Glycol
Nitrogen
Wavelength
Hydroxyl Radical
formal glycol

ASJC Scopus subject areas

  • Materials Chemistry

Cite this

Green, M. M., Gross, R. A., Schilling, F. C., Zero, K., & Crosby, C. (1988). Macromolecular stereochemistry: Effect of pendant group structure on the conformational properties of polyisocyanides. Macromolecules, 21(6), 1839-1846.

Macromolecular stereochemistry : Effect of pendant group structure on the conformational properties of polyisocyanides. / Green, Mark M.; Gross, Richard A.; Schilling, Frederic C.; Zero, Karl; Crosby, Charles.

In: Macromolecules, Vol. 21, No. 6, 1988, p. 1839-1846.

Research output: Contribution to journalArticle

Green, MM, Gross, RA, Schilling, FC, Zero, K & Crosby, C 1988, 'Macromolecular stereochemistry: Effect of pendant group structure on the conformational properties of polyisocyanides', Macromolecules, vol. 21, no. 6, pp. 1839-1846.
Green, Mark M. ; Gross, Richard A. ; Schilling, Frederic C. ; Zero, Karl ; Crosby, Charles. / Macromolecular stereochemistry : Effect of pendant group structure on the conformational properties of polyisocyanides. In: Macromolecules. 1988 ; Vol. 21, No. 6. pp. 1839-1846.
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abstract = "The hydroxyl function of the S enantiomer of the 1,2-acetone ketal of propylene glycol was converted, via the amine, to the isocyanide ([α]546 +32.9° (CHCl3)), which was polymerized by using NiCl2 hexahydrate in the neat state to the derived poly((S)-2,2-dimethyl-1,3-dioxolane-4-methyl isocyanide) ([α]546 +68.5° (p-dioxane); Mw = 165 000). The ultraviolet spectrum of this brown solid in CHCl3 exhibited a band, as a shoulder on lower wavelength absorptions, with λmax = 295 nm and 3.2 × 102 L mol-1 cm-1, and a long low-intensity visible region tail. The circular dichroism (CD) spectrum was similar to published spectra for α-substituted asymmetric polyisocyanides and showed three maxima (λmax, nm; Δ∈, L mol-1 cm-1): 328, -0.082; 290, +0.015; 275, -0.047. High-field 13C NMR studies exhibited extensive chemical shift dispersion for both the backbone carbon and the pendant carbons. Similar shift dispersion was encountered in poly(n-butyl isocyanide) and in poly(benzyl isocyanide). Poly((R)-α-phenylethyl isocyanide) also exhibited chemical shift dispersion superimposed on symmetrical but broadened lines in its 13C NMR spectrum. Zimm plots constructed from wide-angle 633-nm light scattering data on poly((R)-α-phenylethyl isocyanide) (Mw = 107 000) and on poly((5)-2,2-dimethyl-1,3-dioxolane-4-methyl isocyanide) (Mw = 165 000) showed no angular dependence. The weight average hydrodynamic radii of these polymers in tetrahydrofuran were determined by photon correlation spectroscopy to be 51 and 24 {\AA}, respectively. If one adopts a 4/1 helix with a pitch of 4 {\AA} proposed in the literature for poly(α-phenylethyl isocyanide), our data yield a persistence length of 32 {\AA}, which is substantially larger than that for poly((S)-2,2-dimethyl-1,3-dioxolane-4-methyl isocyanide). The results show that some form of stereoirregularity, which could involve syn-anti isomerism about the carbon-nitrogen double bond, is seen in each of the polymers studied. In addition, the chain dimension is strongly dependent on the pendant group structure.",
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T2 - Effect of pendant group structure on the conformational properties of polyisocyanides

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N2 - The hydroxyl function of the S enantiomer of the 1,2-acetone ketal of propylene glycol was converted, via the amine, to the isocyanide ([α]546 +32.9° (CHCl3)), which was polymerized by using NiCl2 hexahydrate in the neat state to the derived poly((S)-2,2-dimethyl-1,3-dioxolane-4-methyl isocyanide) ([α]546 +68.5° (p-dioxane); Mw = 165 000). The ultraviolet spectrum of this brown solid in CHCl3 exhibited a band, as a shoulder on lower wavelength absorptions, with λmax = 295 nm and 3.2 × 102 L mol-1 cm-1, and a long low-intensity visible region tail. The circular dichroism (CD) spectrum was similar to published spectra for α-substituted asymmetric polyisocyanides and showed three maxima (λmax, nm; Δ∈, L mol-1 cm-1): 328, -0.082; 290, +0.015; 275, -0.047. High-field 13C NMR studies exhibited extensive chemical shift dispersion for both the backbone carbon and the pendant carbons. Similar shift dispersion was encountered in poly(n-butyl isocyanide) and in poly(benzyl isocyanide). Poly((R)-α-phenylethyl isocyanide) also exhibited chemical shift dispersion superimposed on symmetrical but broadened lines in its 13C NMR spectrum. Zimm plots constructed from wide-angle 633-nm light scattering data on poly((R)-α-phenylethyl isocyanide) (Mw = 107 000) and on poly((5)-2,2-dimethyl-1,3-dioxolane-4-methyl isocyanide) (Mw = 165 000) showed no angular dependence. The weight average hydrodynamic radii of these polymers in tetrahydrofuran were determined by photon correlation spectroscopy to be 51 and 24 Å, respectively. If one adopts a 4/1 helix with a pitch of 4 Å proposed in the literature for poly(α-phenylethyl isocyanide), our data yield a persistence length of 32 Å, which is substantially larger than that for poly((S)-2,2-dimethyl-1,3-dioxolane-4-methyl isocyanide). The results show that some form of stereoirregularity, which could involve syn-anti isomerism about the carbon-nitrogen double bond, is seen in each of the polymers studied. In addition, the chain dimension is strongly dependent on the pendant group structure.

AB - The hydroxyl function of the S enantiomer of the 1,2-acetone ketal of propylene glycol was converted, via the amine, to the isocyanide ([α]546 +32.9° (CHCl3)), which was polymerized by using NiCl2 hexahydrate in the neat state to the derived poly((S)-2,2-dimethyl-1,3-dioxolane-4-methyl isocyanide) ([α]546 +68.5° (p-dioxane); Mw = 165 000). The ultraviolet spectrum of this brown solid in CHCl3 exhibited a band, as a shoulder on lower wavelength absorptions, with λmax = 295 nm and 3.2 × 102 L mol-1 cm-1, and a long low-intensity visible region tail. The circular dichroism (CD) spectrum was similar to published spectra for α-substituted asymmetric polyisocyanides and showed three maxima (λmax, nm; Δ∈, L mol-1 cm-1): 328, -0.082; 290, +0.015; 275, -0.047. High-field 13C NMR studies exhibited extensive chemical shift dispersion for both the backbone carbon and the pendant carbons. Similar shift dispersion was encountered in poly(n-butyl isocyanide) and in poly(benzyl isocyanide). Poly((R)-α-phenylethyl isocyanide) also exhibited chemical shift dispersion superimposed on symmetrical but broadened lines in its 13C NMR spectrum. Zimm plots constructed from wide-angle 633-nm light scattering data on poly((R)-α-phenylethyl isocyanide) (Mw = 107 000) and on poly((5)-2,2-dimethyl-1,3-dioxolane-4-methyl isocyanide) (Mw = 165 000) showed no angular dependence. The weight average hydrodynamic radii of these polymers in tetrahydrofuran were determined by photon correlation spectroscopy to be 51 and 24 Å, respectively. If one adopts a 4/1 helix with a pitch of 4 Å proposed in the literature for poly(α-phenylethyl isocyanide), our data yield a persistence length of 32 Å, which is substantially larger than that for poly((S)-2,2-dimethyl-1,3-dioxolane-4-methyl isocyanide). The results show that some form of stereoirregularity, which could involve syn-anti isomerism about the carbon-nitrogen double bond, is seen in each of the polymers studied. In addition, the chain dimension is strongly dependent on the pendant group structure.

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