High pressure phase transformations in Bis(glycinium)oxalate - An infrared absorption study

► Bis(glycinium)oxalate shows high pressure transformations across 1.6 and 4.5 GPa. ► Raman modes appear in the IR spectra above 1.6 GPa. ► The high pressure phase above 1.6 GPa is non centrosymmetric in nature. ► The short O-H⋯O hydrogen bond gets strengthened with pressure up to 1.6 GPa. ► Relatively weaker than parent phase, yet strong O-H⋯O bonds exist above 1.6 GPa.