Research data for manuscript: Pressure-induced aggregation of associating liquids as a driving Force enhancing hydrogen bond cooperativity

The behavior of hydrogen bonds under extreme pressure is still not well understood. Until now, the shift of the stretching vibration band of the X–H group (X = the donor atom) in infrared spectra has been attributed to the variation in the length of the covalent X–H bond. Herein, we combined infrared spectroscopy and X-ray diffraction experimental studies of two H-bonded liquid hexane derivatives, i.e., 2-ethyl-1-hexanol and 2-ethyl-1-hexylamine, in diamond anvil cells at pressures up to the GPa level, with molecular dynamics simulations covering similar thermodynamic conditions. Our findings revealed that the observed changes in the X–H stretching vibration bands under compression are not primarily due to H-bond shortening resulting from increased density but mainly due to cooperative enhancement of H-bonds caused by intensified molecular clustering. This sheds new light on the nature of H-bond interactions and the structure of liquid molecular systems under compression.The dataset contains high-pressure FTIR spectra of 2-ethyl-1-hexanol (2E1H) and 2-ethyl-1-hexylamine (2E1HA).