文摘
External stimuli trigger conformational up-conversion in the molecules of di-p-tolyl disulfide (CH3–C6H4–S−)2, compensating the stress and absorbing its energy. These mechanochemical transformations explain at the molecular level the lubricating performance of di-p-tolyl disulfide and suggest new applications for storing energy. High pressure induces the conversion either in the solid state, as a phase transition, or at the nucleation stage on the solution-solid interphase as a detour of crystallization preference. The discontinuous transition at 1.6 GPa reduces the symmetry of ambient-pressure monoclinic phase α (space group P21) to triclinic phase β (space group P1). The recrystallizations above 0.45 GPa yield a new polymorph γ (space group P21/c), most spectacular in the conformational up-conversion absorbing 6 kJmol–1.