Deferiprone: new environmental perspectives. Insights into its sequestering ability vs. different metal cations

Area of Science:

• Coordination Chemistry
• Environmental Chemistry
• Analytical Chemistry

Background:

• Deferiprone (DFP) is a known iron (Fe³⁺) chelator.
• Limited data exists on DFP's interaction with other metal cations.
• Understanding DFP's broader metal-binding capabilities is crucial for potential new applications.

Purpose of the Study:

• To investigate the complexing and sequestering abilities of deferiprone (DFP) towards calcium (Ca²⁺), magnesium (Mg²⁺), cadmium (Cd²⁺), and lead (Pb²⁺).
• To determine the speciation models and formation constants for DFP-metal complexes.
• To evaluate DFP's affinity for these metal ions under varying conditions.

Main Methods:

• Potentiometry and ¹H NMR spectroscopy were employed to study metal-DFP interactions.
• Experiments were conducted in aqueous KCl solutions across a range of ionic strengths (0.1–1.0 mol dm^-3) at 298.15 K.
• Density Functional Theory (DFT) calculations were used to elucidate binding modes.

Main Results:

• Deferiprone forms ML, ML₂, ML₃, and ML(OH) species with Cd²⁺ and Pb²⁺, and ML and ML₂ species with Ca²⁺ and Mg²⁺.
• Formation constants indicate DFP exhibits the strongest complexing and sequestering ability towards Pb²⁺, followed by Cd²⁺, Mg²⁺, and Ca²⁺.
• ¹H NMR and DFT studies confirm DFP's affinity for Cd²⁺ and Pb²⁺, with binding occurring at the hydroxo-oxo moiety of the pyridinone ring.

Conclusions:

• Deferiprone demonstrates significant chelating and sequestering potential for Pb²⁺ and Cd²⁺.
• The findings suggest deferiprone's utility in addressing Pb²⁺ accumulation and overload in environmental and biological contexts.
• This research expands the understanding of deferiprone's coordination chemistry beyond iron.