Pressure-freezing with conformational conversion of 3-aminopropan-1-ol molecules.

3-Aminopropan-1-ol, NH(2)(CH(2))(3)OH, was pressure-frozen and its structure determined at 0.2, 0.9 and 1.31 GPa by single-crystal X-ray diffraction. The freezing pressure of 0.13 GPa at 296 K was measured by ruby fluorescence in the diamond-anvil cell and from compressibility measurement in the piston-and-cylinder reaction press. The molecules assume an extended conformation in the crystalline state, different from the pseudo-ring conformers, with the terminal groups linked by an intramolecular hydrogen bond, present in the gaseous and liquid states. The polar arrangement in the 3-aminopropan-1-ol crystals is explained in terms of the pattern of intermolecular hydrogen bonds.