Magnesium(II)‐ATP Complexes in 1‐Ethyl‐3‐Methylimidazolium Acetate Solutions Characterized by (31)Mg β‐Radiation‐Detected NMR Spectroscopy

The complexation of Mg(II) with adenosine 5′‐triphosphate (ATP) is omnipresent in biochemical energy conversion, but is difficult to interrogate directly. Here we use the spin‐ [Formula: see text] β‐emitter (31)Mg to study Mg(II)‐ATP complexation in 1‐ethyl‐3‐methylimidazolium acetate (EMIM‐Ac) solutions using β‐radiation‐detected nuclear magnetic resonance (β‐NMR). We demonstrate that (nuclear) spin‐polarized (31)Mg, following ion‐implantation from an accelerator beamline into EMIM‐Ac, binds to ATP within its radioactive lifetime before depolarizing. The evolution of the spectra with solute concentration indicates that the implanted (31)Mg initially bind to the solvent acetate anions, whereafter they undergo dynamic exchange and form either a mono‐ ((31)Mg‐ATP) or di‐nuclear ((31)MgMg‐ATP) complex. The chemical shift of (31)Mg‐ATP is observed up‐field of (31)MgMg‐ATP, in accord with quantum chemical calculations. These observations constitute a crucial advance towards using β‐NMR to probe chemistry and biochemistry in solution.