(2-Hydroxyphenyl)phosphonic acid: complexation with the copper(ii) cation, toxicity, and accumulation in HeLa cells

The copper( ii ) complex [Cu(H 2 L 1 ) 2 (H 2 O) 2 ] with (2-hydroxyphenyl)phosphonic acid (H 3 L 1 ) was synthesized. The composition and structure of the complex were determined by X-ray diffraction, elemental analysis, and IR spectroscopy. Quantum chemical calculations of the structure of the H 3 L 1 molecule were performed by the density functional theory (DFT). The protonation constants of H 3 L 1 and the stability constants of its complexes with Cu 2+ in water were determined by potentiometric titration. The cytotoxic properties and the accumulation of the [Cu(H 2 L 1 ) 2 (H 2 O) 2 ] complex in human cervical adenocarcinoma HeLa cells were evaluated for the first time, thereby demonstrating that this complex is promising for further biological studies.