Complexation of flavonoids with iron: structure and optical signatures

The complexation mechanism of several flavonoids with iron is examined by using the first-principles electronic structure calculations based on density functional theory (DFT). Optical absorption spectra have served as signatures for identifying various complexes and for the iron-quercetin complexes, the redshift of the first absorbance peak is described by narrowing the optical gap of quercetin because of Fe(d)-O(p) orbital hybridization.