Zinc(II) Complex with 2-Hydroxy-5-ethylphenylphosponic Acid: Synthesis, Structure, Toxicity, and Accumulation in HeLa Cells

A complex of zinc(II) with 2-hydroxy-5-ethylphenylphosphonic acid (H3L) of the composition [Zn(H2L)2(Н2О)2][Zn(HL)(Н2О)]·H2O (I) was synthesized, the structure of which was established based on data of X-ray diffraction and elemental analysis, quantum chemical calculations, as well as IR and electron absorption spectroscopies. The stability constants of H3L acid complexes with zinc(II) perchlorate in water were determined by potentiometric titration. The cytotoxic properties of H3L acid and complex I were studied for the first time on HeLa cells (human cervical adenocarcinoma). The results on the accumulation of complex I in HeLa cells were obtained by laser confocal microscopy.