Exploring the biological, catalytic, and magnetic properties of transition metal coordination complexes incorporating pyrophosphate

Polyphosphate anions are ubiquitous in nature, none more so than the diphosphate tetra-anion P₂O₇ ⁴⁻, commonly referred to as pyrophosphate (PPi). The past decade has seen a rise in the number of pyrophosphate coordination complexes synthesized and characterized, and the areas of research interest expanded to include magnetic, medicinal, nutraceutical, catalytic and bioinorganic. The aim of the present review is to collect and organize the multidisciplinary information of the inorganic pyrophosphate system paying special attention to the following points: (i) the structural diversity of the PPi-containing metal complexes from discrete species to coordination polymers, which is due to the variety of its coordination modes; (ii) the ability of the PPi ligand to mediate electronic effects between paramagnetic centers when acting as a bridge; (iii) and the biological properties of the PPi complexes, in particular their cytotoxicity and antibacterial and antifungal aspects, having in mind the biocompatibility, solubility and low toxicity of PPi.