Characterization of uniaxially aligned chitin film by 2D FT-IR spectroscopy.
Two-dimensional FT-IR spectroscopy (2D FT-IR) was applied to the investigations of crystalline chitin structure. From this study, new information about spectral bands which are not observed in conventional 1D FT-IR was obtained. In 2D spectra, three specific bands were differentiated at 3482, 3421, and 3380 cm(-1) in the OH region. They could be assigned as C(6)OH groups which are hydrogen-bonded to the next C(6)OH; C(3)OH groups hydrogen-bonded to O(5); and C(6)OH groups bifurcated hydrogen-bonded to C(6)OH as well as C=O, respectively. Two pairs of bands appeared in the amide region, indicating the two types of hydrogen-bonded states of C=O groups. This is in good agreement with the results in the OH region; half of the C(6)OH groups are hydrogen-bonded to C=O as well as the next C(6)OH. The results accurately confirmed the Blackwell model which was established by an X-ray diffraction study. The temperature-dependency of hydrogen-bonds was also revealed by 2D FT-IR. Interchain hydrogen-bonds [C(6)OH...O(6)] first respond to a temperature followed by intrachain [C(6)OH...O=C] and [C(3)OH...O(5)] with increasing temperature. Interchain hydrogen-bonds [NH...O=C] are relatively stable in the temperature range of 40-180 degrees C.
Yamaguchi
Yoshimi
Y
Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. janvier1@adh.fp.a.u-tokyo.ac.jp
Nge
Thi Thi
TT
Takemura
Akio
A
Hori
Naruhito
N
Ono
Hirokuni
H
D000577:Amides / Q000737:chemistry; D002686:Chitin / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013696:Temperature
D000577:Amides; D002686:Chitin