The formation of complexes between alum with morin and quercetin in aqueous solution with and
without pH control have been studied by UV-visible spectroscopy. The stoichiometries of the complexes
were evaluated using the molar ratio method. The association ratio of alum with morin and quercetin
without pH control were 3 : 2 and 1 : 1, respectively. In the buffer system pH 4.5, the stoichiometry of
alum with morin and quercetin were 1 : 1 and 1 : 1, respectively. The heats of formation of complex,
obtained by semi-empirical PM3 method, indicated that the proposed complexes can be favorably
formed.