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

Abstract

Infrared spectra of the neutral dimethylamine−methanol cluster, DMA− CH 3 OH, were measured in the spectral range of 2800−3900 cm −1 using an infraredvacuum ultraviolet (IR-VUV) scheme. Quantum chemical calculations and ab initio molecular dynamic (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 the intermolecular interaction between DMA and CH 3 OH. The present work provides the fundamental understanding of hydrogen-bonding networks in the amine−alcohol complexes.

Vibrational study of methylamine dimer and hydrated methylamine complexes in solid neon supported by ab initio calculations

“…The high concentration of water in Earth's atmosphere makes its interactions with trace molecules important in atmosphere chemistry [2]. The polar NH 2 functional group in amines can form a strong hydrogen bond with water and alcohols and these complexes have given rise to many theoretical studies [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”

Structure, Stability, and Spectroscopic Properties of Small Acetonitrile Cation Clusters

“…As for the N–H stretching in the water complexes, there are two modes combined with the H–O–H bending mode, whose wavenumbers are 1560 and 1802 cm –1 for (CH 2 CNH + )­H 2 O, and 1603 and 2022 cm –1 for (CH 3 CNH + )­H 2 O. Therefore, a strong redshift of the N–H stretch is present for both complexes when compared to the analogous CH n CNH + species, which is a fingerprint of hydrogen bond formation. − All relevant wavenumbers are listed in Table .…”

“…For (CH 3 CN) 2 H + , there are six modes composed of symmetric and asymmetric N–H–N stretching. All of them are significantly red-shifted, which is a further indicative of hydrogen bond formation. − Selected simulated vibrational spectra are present in Figure S8.…”

Determinant Factor for Thermodynamic Stability of Sulfuric Acid–Amine Complexes

“…As the ternary inorganic reaction of sulfuric acid, water, and ammonia was confirmed to be responsible for aerosol nucleation under extremely cold conditions of the middle and upper troposphere, , ammonia was proposed to play an important reactant role in stabilizing small sulfuric acid-water clusters by forming ammonium sulfate and bisulfate salts. − ,, However, this inorganic reaction mechanism was unable to explain the unexpectedly fast formation rate and high concentration of sulfuric acid-containing aerosol particles in the atmosphere yet. Therefore, nucleation and subsequent growth of newly formed particles should be contributed by other chemicals, especially in the highly polluted urban atmosphere. ,,, The corresponding acid–base reactions might predominantly contribute to atmospheric aerosol formation and their growth. − …”

“…Therefore, nucleation and subsequent growth of newly formed particles should be contributed by other chemicals, especially in the highly polluted urban atmosphere. 22,27,38,39 The corresponding acid−base reactions might predominantly contribute to atmospheric aerosol formation and their growth. 40−43 Amines are the common organic derivatives of ammonia and can be released from wide sources.…”