Spectroscopic and theoretical study of the pH effect on the optical properties of the calcium-morin system.

Morin (2-(2,4-dihydroxyphenyl)-3,5,7-trihydroxychromen-4-one) is an abundant flavonoid with various pharmacological and biological activities. Considering the ubiquitous presence of calcium cations in biological systems, it seems relevant to study the interaction of this ion with morin and the influence of pH on this system. In a first step, among the four hypothetical chelation sites, the preferential fixing site, its protonation state and the Ca environment have been determined by combining electronic spectroscopies and density functional theory (DFT) and time-dependent DFT calculations.