Raman Optical Activity of Glucose and Sorbose in Extended Wavenumber Range

• Published in: Chemphyschem Vol. 21; no. 12; pp. 1272 - 1279
• Main Authors: Palivec, Vladimír, Michal, Pavel, Kapitán, Josef, Martinez‐Seara, Hector, Bouř, Petr
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 16.06.2020
• Subjects: Anharmonicity; Aqueous solutions; Carbohydrates; CH stretching; Density functional theory; Glucose; Molecular dynamics; Optical activity; Raman optical activity; saccharide structure; Sorbose; Spectra; spectral modeling; Stretching; Sugar; Wavelengths; CH stretching; Raman optical activity; saccharide structure; spectral modeling; density functional theory
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.202000261

Raman optical activity (ROA) is pursued as a promising method for structural analyses of sugars in aqueous solutions. In the present study, experimental Raman and ROA spectra of glucose and sorbose obtained in an extended range (50–4000 cm−1) are interpreted using molecular dynamics and density functional theory, with the emphasis on CH stretching modes. A reasonable theoretical basis for spectral interpretation was obtained already at the harmonic level. Anharmonic corrections led to minor shifts of band positions (up to 25 cm−1) below 2000 cm−1, while the CH stretching bands shifted more, by ∼180 cm−1, and better reproduced the experiment. However, the anharmonicities could be included on a relatively low approximation level only, and they did not always improve the harmonic band shapes. The dependence on the structure and conformation shows that the CH stretching ROA spectral pattern is a sensitive marker useful in saccharide structure studies. Sweet stretching range: We have measured the so far unexplored CH stretching Raman optical activity signal in two simple sugars and analyzed it with the help of MD and DFT simulations. It appears that the ROA much depends on the structure and conformation, and it is thus suitable for future structural studies as an important spectral mark for saccharides.