Conformational equilibrium of aminoethanol in the gas phase and in solution driven by intra- and intermolecular interactions and solvent polarity.

This article focuses on the conformational equilibrium of aminoethanol (NH₂CH₂CH₂OH) across gas-phase and solution environments using temperature-dependent photoacoustic Raman spectroscopy (PARS) combined with theoretical calculations. Five low-energy conformers were identified in the gas phase, including one with an intramolecular O–H⋯N hydrogen bond (g′Gg′) and four free-OH conformers (gGt, tGt, gGg, tGg). In nonpolar CCl₄ solution, intramolecular hydrogen bonding weakens, favoring conformers stabilized by the gauche effect, while in polar water solutions, aminoethanol preferentially adopts the tGt conformation due to its higher dipole moment, consistent with molecular dynamics simulations. These findings enhance understanding of how solvent polarity influences conformational stability and suggest potential for designing molecular switches responsive to environmental changes.