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Perfluorobutyric Acid and Its Monohydrate: A Chirped Pulse and Cavity Based Fourier Transform Microwave Spectroscopic Study
Author(s) -
Thomas Javix,
Serrato Agapito,
Lin Wei,
Jäger Wolfgang,
Xu Yunjie
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201304321
Subject(s) - conformational isomerism , chemistry , hydrogen bond , dipole , trifluoroacetic acid , ab initio , fourier transform , ab initio quantum chemistry methods , pulse sequence , microwave , spectral line , rotational spectroscopy , molecule , nuclear magnetic resonance , physics , organic chemistry , quantum mechanics , astronomy
Rotational spectra of perfluorobutyric acid (PFBA) and its monohydrate were studied with a broadband chirped pulse and a narrow‐band cavity based Fourier transform microwave spectrometer, and high‐level ab initio calculations. Extensive conformational searches were performed for both the acid and its monohydrate at the MP2/6‐311++G(2d,p) level of theory. Two and three conformers were predicted to exist for PFBA and its monohydrate, respectively. One set of rotational transitions was observed and assigned for each, PFBA and its monohydrate. Based on the measured broadband spectra, we confidently conclude that only one dominant conformer exists in each case. The orientation of the hydroxyl group in PFBA was determined by using isotopic analysis. Comparison of the observed transition intensities and the calculated electric dipole moment components allowed us to identify the most stable monohydrate conformation, which takes on an insertion hydrogen‐bonding topology. Comparisons to the shorter chain analogues, that is, trifluoroacetic acid, perfluoropropionic acid, and their monohydrates, are made to elucidate the general trend in their conformational preference and binding topologies.