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Substituent Effects on the Low‐Frequency Vibrational Modes of Benzoic Acid and Related Compounds
Author(s) -
Ge Min,
Zhao HongWei,
Wang WenFeng,
Yu XiaoHan,
Li WenXin
Publication year - 2007
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.200790054
Subject(s) - chemistry , substituent , benzoic acid , intermolecular force , hydrogen bond , density functional theory , terahertz radiation , absorption spectroscopy , absorption (acoustics) , spectroscopy , spectral line , infrared spectroscopy , inductive effect , photochemistry , analytical chemistry (journal) , computational chemistry , molecule , stereochemistry , organic chemistry , optics , physics , quantum mechanics , astronomy
Well‐resolved absorption spectra of benzoic acid and its derivatives with one hydrogen atom replaced by a substituent group CH 3 , OH, NH 2 or NO 2 were reported in the frequency region between 6 and 67 cm −1 at room temperature with terahertz time‐domain spectroscopy (THz‐TDS). These substances can be distinguished easily based on the terahertz absorption spectra. The measurements suggested that even minor changes in the molecular configuration and chemical composition lead to distinct differences in THz spectrum. Density functional theory (DFT) method was used to assist the analysis and assignment of the individual THz absorption spectra of benzoic acid and its methyl derivatives. Observed THz responses of samples can be assigned to the collective vibrations associated with intermolecular hydrogen bonds.