Conformational equilibria in acrolein–CO2: the crucial contribution of n → π interactions unveiled by rotational spectroscopy

• Published in: Physical chemistry chemical physics : PCCP 2024-07, Vol.26 (27), p.18865-18870
• Main Authors: Wang, Hao, Chen, Junhua, Tian, Xiao, Wang, Chenxu, Lan, Junlin, Liu, Xingchen, Zhang, Zhenhua, Wen, Xiaodong, Gou, Qian
• Format: Article
• Language: English
• Subjects: Acrolein; Aldehydes; Carbon dioxide; Carbon sequestration; Fourier transforms; Hydrogen bonds; Isomers; Luminous intensity; Rotational spectra; Spectroscopic analysis; Vapor phases
• ISSN: 1463-9076; 1463-9084; 1463-9084
• DOI: 10.1039/d4cp01650e

Using gas phase Fourier-transform microwave spectroscopy complemented by theoretical analysis, this study delivers a comprehensive depiction of the physical origin of the ‘n → π* interaction' between CO2 and acrolein, one of the most reactive aldehydes. Three distinct isomers of the acrolein–CO2 complex, linked through a C⋯O tetrel bond (or n → π* interaction) and a C–H⋯O hydrogen bond, have been unambiguously identified in the pulsed jet. Relative intensity measurements allowed estimation on the population ratio of the three isomers to be T1/T2/C1 ≈ 25/5/1. Advanced theoretical analyses were employed to elucidate the intricacies of the noncovalent interactions within the examined complex. This study not only sheds light on the molecular underpinnings of n → π* interactions but also paves the way for future exploration in carbon dioxide capture and utilization, leveraging the fundamental principles uncovered in the study of acrolein–carbon dioxide interactions.