A cobalt(ii) complex with unique paraSHIFT responses to anionsElectronic supplementary information (ESI) available. See DOI: 10.1039/c7cc00619e

ParaSHIFT agents have shown promise in detecting chemical targets in biological systems by magnetic resonance, but few studies have used transition metal complexes for this purpose. Here we report our investigations into CoMe 6 trenCl (tren = tris(2-aminoethyl)amine) as a paraSHIFT agent. The paramagnetic region of the 1 H NMR spectrum shows characteristic spectral profiles in the presence of fluoride, acetate, lactate and citrate in aqueous solution. These distinctive NMR shifts of each anion are maintained even in mixtures of anions. A cobalt( ii ) complex can distinguish between anions by observing the paramagnetic 1 H NMR shift.