Terahertz spectral identification and low-frequency vibrational analysis of dinitrotoluene isomers

Liu Quancheng; Deng Hu; Li Hongzhen; Wang Minchang; Zhang Qi; Kang Ying; Shang Liping

doi:10.1016/j.saa.2022.121722

Terahertz spectral identification and low-frequency vibrational analysis of dinitrotoluene isomers

Spectrochim Acta A Mol Biomol Spectrosc. 2022 Dec 15:283:121722. doi: 10.1016/j.saa.2022.121722. Epub 2022 Aug 6.

Authors

Liu Quancheng¹, Deng Hu², Li Hongzhen³, Wang Minchang⁴, Zhang Qi³, Kang Ying⁴, Shang Liping²

Affiliations

¹ School of Information Engineering, Southwest University of Science and Technology, Mianyang, China. Electronic address: Liuqc@swust.edu.cn.
² School of Information Engineering, Southwest University of Science and Technology, Mianyang, China.
³ Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang, China.
⁴ State Key Laboratory of Fluorine&Nitrogen Chemicals, Xi'an Modern Chemistry Research Institute, Xi'an, China.

PMID: 35952591
DOI: 10.1016/j.saa.2022.121722

Abstract

Identifying dinitrotoluene (DNT) isomers has always been a challenging problem. In this study, five DNT isomers were investigated using terahertz time-domain spectroscopy (THz-TDS), which demonstrated significant spectral differences including variations in absorption positions and intensities. This suggests that THz-TDS is ideal for rapid identification of DNT isomers. We also employed density functional theory to further discuss the origin of these spectral differences. The results indicate that steric effects between substitute groups, rather than inter-molecular hydrogen bonding, lead to differences in low-frequency vibrations.

Keywords: Density functional theory; Dinitrotoluene isomers; Low-frequency vibration; Steric effects; Terahertz spectroscopy.