Infrared Spectroscopy of Hydrogen Bonding Interactions in Neutral Dimethylamine-Methanol Complexes

Infrared spectra of neutral dimethylamine-methanol cluster, DMA-CH3OH, were measured in the spectral range of 2800-3900 cm-1 using infrared-vacuum ultraviolet (IR-VUV) scheme. Quantum chemical calculations and ab initio molecular dynamics (AIMD) simulations were carried out to understand the experimental spectral features. Experimental and theoretical results reveal the coexistence of N---HO and O---HN hydrogen-bonded structures. AIMD simulations show that the methyl group in methanol internally rotates around the N---O axis, addressing the dynamic effect of the fluctuation of hydrogen bonds on the vibrational features. The bonding analysis was performed to elucidate the nature of intermolecular interaction between DMA and CH3OH. The present work provides the fundamental understanding of hydrogen bonding networks in the amine-alcohol complexes.