Deep eutectic solvents comprising creatine and citric acid and their hydrated mixtures

We report the phase diagram for the binary creatine–citric acid mixture which features a stable and broad eutectic region. Combinations containing 10–60 mol% creatine yield a deep eutectic solvent with a glass transition temperature at 270 K. Addition of up to 70 mol% water to the binary mixture affords retention of the eutectic nature and a handle to vary solvent viscosity and polarity.