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Quercetin and its analogues: optical and acido-basic properties
Michal Biler1, David Biedermann, Kateřina Valentová
1Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University, Šlechtitelů 27, 783 71, Olomouc, Czech Republic. martin.kubala@upol.cz michal.biler@seznam.cz.
Physical Chemistry Chemical Physics : PCCP
|September 28, 2017
Summary
Structural analysis of eight natural flavonoids reveals how their UV/Vis absorption properties change with pH. Key structural features, like the C2-C3 bond, dictate spectral shifts and deprotonation behavior, impacting their use in various industries.
Area of Science:
- * Photochemistry and Molecular Spectroscopy
- * Natural Product Chemistry
- * Computational Chemistry
Background:
- * Flavonoids are natural compounds with diverse biological activities relevant to pharmacy, cosmetics, and food.
- * Understanding their physico-chemical properties is crucial for optimizing their applications.
- * UV/Vis absorption and pH dependence are key properties influenced by molecular structure.
Purpose of the Study:
- * To correlate the structure of eight analogous natural flavonoids with their fundamental physico-chemical properties.
- * To investigate the UV/Vis absorption characteristics and pH-dependent behavior of these flavonoids.
- * To elucidate the role of specific structural motifs, such as the C2-C3 bond and hydroxyl/sugar substitutions, on spectral properties.
Main Methods:
- * Combined experimental spectroscopic measurements and theoretical computational approaches.
- * Analysis of UV/Vis absorption spectra across a range of pH conditions.
- * Molecular Orbital (MO) analysis to rationalize observed spectral changes and electronic properties.
Main Results:
- * The presence or absence of the C2-C3 double bond significantly alters UV/Vis absorption, shifting bands between UVB and UVA regions.
- * Deprotonation in alkaline conditions causes distinct spectral changes: intensity shifts for single bonds (allowing pKa calculation) and bathochromic shifts for double bonds.
- * High pH can induce multiple deprotonations, forming long-wavelength peaks; C3 substitution effects vary with the specific flavonoid structure.
Conclusions:
- * Fundamental physico-chemical properties, particularly UV/Vis absorption and pH response, are directly linked to flavonoid structural motifs.
- * The C2-C3 bond is a critical determinant of spectral behavior and pH-induced electronic changes.
- * These findings provide insights into the behavior of flavonoids in different environments, aiding their application in various industries.
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