A potentiometric, spectrophotometric and NMR study of protonation and formation equilibria of four new iron chelators

The use of chelating agents for iron overload diseases has found ever increasing attention [1-2]. The different drawbacks presented by the chelating agents nowadays in use ask for research on new chelating drugs. In the frame of our research on FeIII and AlIII chelators, a number of ligands containing two kojic acid units joined by different linkers were designed, synthesized, characterized by solid state X-ray diffraction and quantum chemical calculation, and their protonation and FeIII and AlIII complex formation equilibria, using a variety of techniques such as potentiometry, spectrophotometry, ESI-MS, NMR, were exhaustively studied [3-7]. ligands bearing in the linker a vanillin/ortho-vanillin residue were found promising as iron chelators. Here we will present four similar molecules in which the vanillin/orthovanillin residue has been substituted by an aromatic ring containing a carboxylic or a phenolic substituent. Being a phenolic group characterized by a pK ~ 9 and a carboxylic by a pK ~ 4, this substitution was intended to evaluate how the protonation constant affects the pMe value. The topic of this poster will be the study of protonation and metal complex formation equilibria by potentiometric, spectrophotometric and NMR methods.