The crucial role of the inter-ring hydrogen bond to explain the properties of morin

Abstract

The interaction of the Zn^II cation with a multi-site ligand (morin) has been studied to find out the structure of the complex that was not precisely determined in previously published works. The association of electronic spectroscopy measurements and quantum chemistry computations was fruitful to assign the binding site of the cation to the α-hydroxy-ketone site and to bring more precision on part of its environment. The important role of the inter-ring hydrogen bond is especially illustrated by its influence on acid–base properties. Post-analyses based on quantum chemistry (electronic transitions and electron density studies) give more insights into the nature of bonding in this complex and into some fortuitous similarities between the electronic spectra of the deprotonated morin and its complexes.