INS, DFT and temperature dependent IR studies on dynamical properties of acetylcholine chloride

•Acetylcholine chloride was investigated by INS and IR.•DFT calculation for solids state model was performed.•Full vibrational analysis was performed.•Activation energy for reorientation of the whole N(CH3)3 group was obtained.

The acetylcholine chloride (2-acetoxy-N,N,N-trimethylethanaminium chloride) was investigation by inelastic neutron scattering and temperature dependent infrared spectroscopy. The infrared spectra in the temperature range 9–300 K were collected. The density functional theory calculation with the periodic boundary conditions was used for an experimental data analysis. Bands assigned to the CH3 torsion vibration in the acetylcholine cation were observed at 207, 296, 345 and 359 cm−1 in INS spectrum. Activation energy for reorientational motion of the whole N(CH3)3 fragment was determined by means of band shape analysis performed for symmetric stretching vibration of this group. The estimated energy is equal to Ea = 5.3(3) kJ/mol.