Synthesis, solid-state characterization and solution studies of new phytate compounds with Cu(ii) and 1,10-phenanthroline: progress in the structural elucidation of phytate coordinating ability

Abstract

Within all the eukaryotic cells there is an important group of biomolecules that has been potentially related to signalling functions: myo-inositol phosphates (InsP_s). In nature, the most abundant member of this family is the so called phytate (InsP₆, L¹²⁻). The importance of the interaction of InsP₆ with cations has been recognized during the last few years, and any attempt to know the function of this molecule in eukaryotic cells must include the fact that InsP₆ will be strongly associated with simple inorganic or organic ammonium cations. In this work we expand on our earlier findings by studying the systems phen–phytate (phen = 1,10-phenanthroline) and Cu(II)–phen–phytate. The structures of (Hphen)₄(H₈L)·7.5H₂O and [Cu₅(H₇L)₂(H₂O)₂(phen)₅]·23H₂O are presented. Solution studies of the binary and ternary systems were also performed by means of potentiometric titrations at 37.0 °C and 0.15 M ionic strength. The work was completed with a molecular modelling study. All this information is essential in the process of gaining reliable structural knowledge about the most important InsP₆ species in the in vitro and in vivo experiments, and how these features modulate their probable biological functions.