A DSC study of the non-isothermal cold crystallization and relaxation effects in ubiquinone and ubiquinol†

Cold crystallization effects, the kinetics-dependent crystallization behaviour of amorphous ubiquinone and ubiquinol produced in a series of quenching from-the-melt experiments, have been extensively studied through the combination of differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) techniques under a big diversity of experimental conditions, which has allowed the exploration of their poorly understood polymorphic landscapes. The investigation revealed the existence of a non-previously described polymorph together with a rich set of kinetically dependent transformations, which were observed for the first time by thermal analysis conducted at different heating rates in both oxidized and reduced solid forms of Coenzyme Q10.