Study of N-Acetylamino Saccharides with Synchrotron-Based Ultraviolet Resonance Raman Spectroscopy: In Combination...

Area of Science:

• Spectroscopy
• Biochemistry
• Quantum Chemistry

Background:

• Resonance Raman (RR) effects, including pre-resonance and true resonance, are crucial for understanding molecular vibrations.
• Electronic transitions in the far-ultraviolet (FUV) region involve σ and π orbitals, but their geometric orientations in resonance effects are not well-studied.
• Monosaccharides and their derivatives, particularly those with amino groups, exhibit strong FUV absorption.

Purpose of the Study:

• To investigate resonance Raman (RR) effects in glucose, galactose, N-acetylglucosamine, and N-acetylgalactosamine using ultraviolet resonance Raman (UVRR) and FUV spectroscopies.
• To elucidate the role of electronic transitions in the FUV region and their geometric orientations in RR enhancement.
• To explore the contribution of amino and saccharide groups to the observed Raman signals.

Main Methods:

• Utilized ultraviolet resonance Raman (UVRR) spectroscopy with excitation wavelengths of 213, 226, and 250 nm.
• Employed far-ultraviolet (FUV) spectroscopy to analyze electronic transitions.
• Performed quantum chemical calculations to interpret spectral data and electronic transitions.

Main Results:

• Quantum chemical calculations indicated that the FUV absorption band near 190 nm comprises multiple electric transitions.
• UVRR spectra demonstrated significant enhancement of Raman bands associated with the amino group, attributed to multiple electronic transitions.
• Raman bands originating from the saccharide groups showed only slight enhancement.

Conclusions:

• Combined UVRR and FUV spectroscopies offer valuable insights into the geometry and symmetry of electronic transitions within σ and π orbitals.
• The amino group plays a significant role in enhancing UVRR signals through multiple electronic transitions.
• This approach provides a deeper understanding of the spectroscopic properties of monosaccharides and their derivatives.