IntramolecularInteractions in 2-Aminoethanoland 3-Aminopropanol.

Gas-phasevibrational spectra of 2-aminoethanol and 3-aminopropanolwere recorded up to the third OH-stretching overtone using Fouriertransform infrared spectroscopy, cavity ringdown spectroscopy, andintracavity laser photoacoustic spectroscopy. The experimental investigationwas supplemented by local mode calculations, and the intramolecularinteractions were investigated using atoms in molecules (AIM) andnoncovalent interactions (NCI) theories. All calculations were performedat the CCSD(T)-F12a/VDZ-F12 level of theory. For both compounds themost abundant conformer has a structure that allows for hydrogen bondinteraction from the OH group to the N atom of the amino group (OH–N).The spectra show signals from both hydrogen bonded and free OH stretches,implying the presence of several conformers. We observe hydrogen-bond-likeinteractions in both compounds. The red shift of the bonded OH-stretchingfrequency and intensity enhancement of the fundamental transitionsuggest that the hydrogen bond interaction is more pronounced in 3-aminopropanol.AIM analysis supports the presence of a hydrogen bond in 3-aminopropanolbut not in 2-aminoethanol, whereas NCI analysis shows hydrogen bondingin both compounds with the stronger interaction found in 3-aminopropanol. [ABSTRACT FROM AUTHOR]