Kunio Fukushima

Molecular Vibrations and Structure of High Polymers. III. Polarized Infrared Spectra, Normal Vibrations, and Helical Conformation of Polyethylene Glycol

The polarized infrared spectra of highly oriented crystalline films of polyethylene glycol were measured in the region 3500–400 cm—1. Five parallel bands and eleven perpendicular bands due to the fundamental vibrations were observed in the region 1500–600 cm—1. From the analysis of these bands, the polyethylene glycol chain was found to belong to the dihedral group and have twofold axes intersecting the helix axis at right angles. The structural models of polyethylene glycol were discussed by the use of the equations for the helical parameters (the second paper of this series). The most likely model (TGT) contains seven repeating units and two helical turns per fiber period of 19.25 A. The internal rotation angles for this model are calculated to be 60° for the C–C bond and 191.5° for the C–O bond. The A1, A2, and E(θ) normal vibrations of polyethylene glycol were calculated by the general method for treating helical polymers (the first paper of this series). The normal vibrations of p‐dioxane were also c...

Infrared spectrum and normal vibrations of cyclohexane

The infrared spectra of cyclohexane have been studied in the region of 4000-150 cm−1 in the liquid and vapor states. The infrared band due to the Eu skeletal deformation vibration was found at 248 cm−1. The calculation of Coriolis coupling constants has also been carried out along with the normal coordinate treatment using a modified Urey-Bradley force field. The assignment of the infrared and Raman bands was made with reference to the results of this calculation.

Molecular Vibration and Structure of High Polymers. IV. A General Method of Treating Degenerate Normal Vibrations of Helical Polymers and Infrared‐Active Vibrations of Isotactic Polypropylene

Polarized infrared spectra of an oriented crystalline film of isotactic polypropylene have been measured in the region 600–300 cm—1. Two parallel bands and three perpendicular bands due to the skeletal deformation modes have been observed. A general method for treating the normal vibrations (with any given phase difference) of infinite helical chain polymers has been restudied. The method has been applied to the infrared active normal vibrations, A and E(⅔π), of isotactic polypropylene. The modified Urey—Bradley force field has been used and the potential constants have been transferred from aliphatic hydrocarbons. The calculated frequencies and potential energy distributions have been used as aids in assigning the infrared bands of isotactic polypropylene in the region 1500–300 cm—1.

Normal coordinate treatments of internal-rotation vibrations

Abstract The general formulas of the G-matrix elements associated with internal-rotation coordinates are tabulated. The normal vibrations of the trans and gauche isomers of dichloroethane were treated by the use of the internal-rotation potential.

Far Infrared Spectra, Chain Vibrations and Conformations of Polypeptides

The far infrared spectra of poly-L-alanine, poly-γ-methyl-L-glutamate, poly-γ-benzyl-L-glutamate and lysozyme were measured in the region below 800 cm-1. For lysozyme, the amide V bands due to the extended form, the disordered form and the α-helical form are observed at about 690, 650 and 600 cm-1 respectively. Low-frequency bands possibly arising from the α-helical main chain were observed at 375 cm-1 for poly-L-alanine and at about 410 cm-1 for poly-α, L-glutamate esters (methyl or benzyl). The infrared active chain vibrations were treated for the poly-L-alanine chains in the right-handed α-form and in the extended ∈-form and the nature of the observed infrared bands were elucidated. The correlations between the amide V bands and the chain conformations of polypeptide chains were also analysed. The chain vibrations of the left-handed α-helical form were also treated for analysing the infrared spectra of poly-L-aspartate esters. The dependences upon the helical senses are discussed for the amide I, II and V bands of the α-helical form.