Curcuminoids and acetylacetone: iron complexes as studied by electrospray ionization mass spectrometry

Curcumin complexes with iron ions were investigated by electrospray ionization mass spectrometry. It was shown that in methanol solutions of curcumin and iron(III) ions, complexes are formed with a stoichiometry of 1 : 1, 2 : or 3 : 1. Curcumi-iron(II) complexes were created only with the 1 : 1 stoichiometry. Abundances of the 1 : 1 ions depend on the source of iron [(II) or (III)] and the reduction process of iron(III) by higher cone- voltage values. A counter-ion for the iron cation does not affect the types of formed complexes. For comparison, methanol solutions of acetylacetone (acac) and mixtures of acac and curcumin with iron salts were also investigated.