α- L -Tyrosine under high pressure: validation of phase transitions and a curious similarity with L -alanine

The baric behavior of α-L-tyrosine, an aromatic amino acid, was investigated using single-crystal X-ray diffraction. Around 2 GPa, the nonlinear behavior in the compression of unit-cell parameters a and c was observed, as N—H...O hydrogen bonds involving the NH 3 + group switched over. This rearrangement is remarkably similar to the changes observed in crystalline L-alanine at comparable pressures. A comparison of intermolecular interactions in L-alanine and α-L-tyrosine is performed in order to suggest an interpretation of structural strain on hydrostatic compression.