Complexation of iron(III) by catecholate-type polyphenols

We report here a complete physico-chemical study of the chelation of iron(III) by catechin (L¹), an abundant polyphenol in green tea. Using a fruitful combination of electrospray mass spectrometry, absorption spectrophotometry and potentiometry, we have characterized three ferric complexes of catechin (L¹Fe, and (L¹)₃Fe) as well as a ternary complex L¹FeNTA when an exogenous ligand (nitrilotriacetic acid) is added to the medium. Thanks to this study, we discuss the influence of an exogenous tetradentate ligand in the ferric recognition processes by catecholate-type polyphenols.