Structural study on polymorphism of long-chain dicarboxylic acids using oblique transmission method for micro FT-IR spectrometers.
Polymorphism and higher-order structures of even-number dicarboxylic acids from hexadecanedioic acid to eicosanedioic acid have been studied by micro-FTIR spectroscopy and microscopic observation. In order to obtain the three-dimensional structural information, the oblique transmission method was incorporated into a micro-FTIR spectrometer equipped with a couple of Cassegrain lenses. The IR spectra showed that the solid states of dicarboxylic acid bore a marked structural similarity to those of n-saturated fatty acids. It was found that a solution-grown single crystal of dicarboxylic acids was an aggregate of lamellae whose thickness exceeded by far their molecular length. The surfaces of lamellae were covered with hydrocarbon segments taking a hairpin structure, and the linkage of hydrogen-bonded dicarboxylic acids formed a folded chain structure. The result of oblique transmission measurements showed that the stacking mode of lamellae varied depending on crystallization conditions.
Kaneko
Fumitoshi
F
Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560, Japan. toshi@chem.sci.osaka-u.ac.jp
Ishikawa
Eiichi
E
Kobayashi
Masamichi
M
Suzuki
Masao
M
D055592:Biophysical Phenomena; D001703:Biophysics; D003460:Crystallization; D003998:Dicarboxylic Acids / Q000737:chemistry*; D004537:Eicosanoic Acids / Q000737:chemistry; D011110:Polymorphism, Genetic; D017510:Protein Folding; D017550:Spectroscopy, Fourier Transform Infrared / Q000295:instrumentation* / Q000379:methods*
D003998:Dicarboxylic Acids; D004537:Eicosanoic Acids