The pH-specific synthesis, spectroscopic, structural, and magnetic properties of a new Ni(II) species containing the plant physiological binder d-(−)-quinic acid: Association with the aqueous speciation of the binary Ni(II)–quinate system

Nickel is an element present in the abiotic and biological world. In its capacity to promote chemistry at the cellular level, Ni(II) interacts with physiological ligands, thus influencing physiological or pathological conditions. Efforts to comprehend the underlying chemistries led to the investigation of Ni(II) reactivity toward the physiological d-(−)-quinic acid, under pH-specific conditions, facilitating the isolation of a new species Na[Ni(C7H11O6)3] · 2.75H2O (1). Compound 1 was characterized by elemental analysis, spectroscopic techniques (FT-IR, UV–Visible), magnetic susceptibility studies, and X-ray crystallography. The lattice of 1 reveals the presence of an octahedral Ni(II) complex bound to three quinate ligands through the α-hydroxycarboxylate group, thus projecting a stable entity. Concurrent aqueous speciation studies on the Ni(II)–quinate binary system unravel the nature and properties of species arising from Ni(II)–quinate interactions. To this end, the structural and spectroscopic properties of 1, in the solid state and in solution, are in line with the aqueous speciation, exemplifying key features of Ni(II) interactions with the low molecular mass quinic acid in biologically relevant fluids. The overall physicochemical profile of 1 projects well-defined soluble and potentially bioavailable Ni(II) species that could be involved in specific chemical processes and (bio)chemical reactivity patterns at the physiological or molecular toxicity level.

Reaction of Ni(II) with d-(−)-quinic acid (pH ∼5.5) leads to a new species Na[Ni(C7H11O6)3] · 2.75H2O(1), characterized analytically, spectroscopically, magnetically, and structurally. The physicochemical profile of 1 is reflected into its partner [NiL2]0 species in the aqueous speciation of the Ni(II)–quinate binary system, thus aiding in understanding of Ni(II)–hydroxycarboxylate interactions in cellular physiology/toxicity.Figure optionsDownload as PowerPoint slide