A ‘shiftless’ relaxation reagent for metal nuclide and nitrogen-15 magnetic resonance in aqueous solution†

Addition of small amounts of [Gd(2 : 2 : 1)]^(3+) cryptate to aqueous solutions containing ^(111)Cd^(2+) or formamide decreases metal nuclide or nitrogen-15 spin-lattice (T_1) relaxation times without affecting cadmium or nitrogen chemical shifts. This cryptate is thereby demonstrated to have substantial promise for greatly decreasing the time necessary to obtain natural abundance metal nuclide or ^(15)N NMR spectra with satisfactory signal-to-noise ratios for many compounds with long metal or ^(15)N relaxation times.