NMR monitoring of nonequilibrium aggregation in ionic solutions

The complex shaped 1H NMR signal of [C10mim][Br] has been observed after it was mixed with water. Within minutes the contour transformed into Voigt (V) profile with Gauss (G) contribution as dominant and started to evolve towards Lorentz-shaped (L) contour. Relative G/L contribution in V-profile was proposed as the measure of nonequilibrium aggregation in mesoscopic/supramolecular scale. The equilibration kinetics was monitored by time dependence of the half-widths G/L with waiting time up to 2–4 days. The ‘nonequilibrium’ covers only certain degrees of freedom of the guest (ionic liquid) molecules, whereas the matrix, i.e. the hydrogen-bonded network of water, is equilibrated.