Structural, electronic, and optical properties of representative Cu-flavonoid complexes.

Area of Science:

• Computational Chemistry
• Materials Science
• Biochemistry

Background:

• Flavonoids are natural compounds with antioxidant properties.
• Copper-flavonoid complexes are of interest for their potential biological activities.
• Understanding complexation mechanisms is crucial for elucidating their function.

Purpose of the Study:

• To investigate the structural, electronic, and optical properties of copper-flavonoid complexes using DFT.
• To determine preferred chelating sites and analyze electronic transitions.
• To correlate theoretical findings with experimental UV-vis spectra and pH-dependent behavior.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Analysis of structural, electronic, and optical properties.
• Time-dependent DFT for optical absorption spectra.

Main Results:

• Identified preferred chelating sites involving the 4-oxo group and B-ring dihydroxy groups.
• Observed significant bathochromic shifts in optical absorption due to reduced energy gaps.
• HOMO-LUMO transitions were characterized, with pi-pi transitions dominating and sigma-pi transitions present in the 1:1 complex.
• Correlated specific complexes (1:1 and 1:2) with experimental spectra at different pH values (5.5 and 7.4).

Conclusions:

• DFT provides detailed insights into copper-flavonoid complexation.
• The study elucidates the electronic origins of observed optical properties.
• Theoretical predictions support experimental findings and aid in understanding antioxidant mechanisms.