Colossal Monotonic Response to Hydrostatic Pressure in Molecular Crystal Induced by a Chemical Modification

Monotonic compression of 2-methylbenzimidazole mimics the pressure-induced discontinuous transition between benzimidazole phases β and γ. Both are built of similarly arranged chains of NH···N bonded molecules. Although the methyl substituents prevent the collapses of voids, 2-methylbenzimidazole monotonically follows the abrupt lattice strain of benzimidazole. This generates the effects of giant linear compression and negative-area compression in 2-methylbenzimidazole. The observation of converted discontinuous and monotonic compression provides a new method for engineering materials of required elastic properties