A theoretical study of hydrogen-bonded molecular clusters of sulfuric acid and organic acids with amides

Qingzhu Zhang , Chenpeng Zuo , Xianwei Zhao , Hetong Wang , Xiaohui Ma , Siyuan Zheng , Fei Xu


Received August 14, 2019,Revised , Accepted July 25, 2020, Available online August 16, 2020

Volume 100,2021,Pages 328-339

Amides, a series of significant atmospheric nitrogen-containing volatile organic compounds (VOCs), can participate in new particle formation (NPF) throught interacting with sulfuric acid (SA) and organic acids. In this study, we investigated the molecular interactions of formamide (FA), acetamide (AA), N-methylformamide (MF), propanamide (PA), N-methylacetamide (MA), and N,N-dimethylformamide (DMF) with SA, acetic acid (HAC), propanoic acid (PAC), oxalic acid (OA), and malonic acid (MOA). Global minimum of clusters were obtained through the association of the artificial bee colony (ABC) algorithm and density functional theory (DFT) calculations. The conformational analysis, thermochemical analysis, frequency analysis, and topological analysis were conducted to determine the interactions of hydrogen-bonded molecular clusters. The heterodimers formed a hepta or octa membered ring through four different types of hydrogen bonds, and the strength of the bonds are ranked in the following order: SOsingle bondH•••O > COsingle bondH•••O > Nsingle bondH•••O > Csingle bondH•••O. We also evaluated the stability of the clusters and found that the stabilization effect of amides with SA is weaker than that of amines with SA but stronger than that of ammonia (NH3) with SA in the dimer formation of nucleation process. Additionally, the nucleation capacity of SA with amides is greater than that of organic acids with amides.

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