Chrysin amd Quercetin complexes with Cu(II): A spectroscopic and photochemical study

VANESA MUÑOZ; SANDRA MISKOSKI; MATIAS I. SANCHO; GABRIELA FERRARI; NORMAN GARCÍA; MARIA P. MONTAÑA

Córdoba

Congreso; 13 Conferencia Latinoamericana de Fisicoquímica Orgánica; 2015

INFIQC-CONICET

Chrysin and Quercetin are natural polyphenolic componds wich presents benefits in human health because of their biological properties. These flavonoids also have the capcacity to complex a wide variety of metallic ions which could affect their bioactivity. In order to assay the complexant capcacity of flavonoids, the metallic ion Cu(II) was selected. Formation of two flavonoid-Cu(II) complexes in ethanolic solutions were studied. A molecular modeling analysis was performed in order to gain an insight of the spectroscopic properties of the complexes. Beside that, a photochemical study of chrysin and its metallic compelex was carried out. Chrysin-Cu(II) and Quercetin-Cu(II) complexes presented 2:1 L:M stoichiometries. The apparent formation constants of Quercetin:Cu(II) are higher than those of Chrysin-Cu(II) ones, suggesting than Quercetin may act as a better analytical reagent. The same trend was observed in the theoretical formation constants obtained by DFT methods. On the basis of TD-DFT results UV-Vis spectra of the complexes were simulated employing different functionals and their absorption bands were characterized by means of Natural Transition Orbital analysis.Riboflavin-sensitized Chrysin and Chrysin-Cu(II) ethanolic solutions were irradiated. The spectral evolution of the systems showed substrates consumption. The oxygen uptake in presence and absence of specific quencher of reactive oxygen species made evident the participation of singlet molecular oxygen (O2 (1Dg)) in the flavonoid and its metallic complex photoconsumption.  Therefore, total O2 (1Dg) quenching (kt), reactive O2 (1Dg) quenching (kr) and 3Rf* quenching constants were determinated.