title: Computational and vibrational spectroscopic studies of ipratropium bromide.
abstract: In this study, ipratropium bromide is investigated using vibrational spectroscopy and quantum chemical calculations. The structure of ipratropium bromide was optimised using density functional theory calculations and the geometry optimisation has been carried out on two conformations with and without intramolecular hydrogen bonding. Infrared and Raman spectra were calculated from the optimised structures. Many modes in the calculated spectra could be matched with the experimental spectra and a description of the modes is given. By analysis of the theoretical vibrational modes, it is shown that ipratropium bromide specimens are likely to be a mixture of the two conformations with and without intramolecular hydrogen bonding. In addition, several spectral features and band intensities in the CH and OH stretching regions are explained. Quantum mechanical calculations allowed improved understanding of ipratropium bromide and its vibrational spectra.
authors.affiliation: Molecular Spectroscopy Group, Analytical Centre and Chemical and Forensic Sciences, School of Life Sciences, University of Bradford, Bradford, BD7 1DP, UK.
authors.forename: H R H
authors.initials: HR
authors.lastname: Ali
authors.forename: H G M
authors.initials: HG
authors.lastname: Edwards
authors.forename: J
authors.initials: J
authors.lastname: Kendrick
authors.forename: I J
authors.initials: IJ
authors.lastname: Scowen
mesh_terms: D001993:Bronchodilator Agents / Q000737:chemistry*; D006860:Hydrogen Bonding; D009241:Ipratropium / Q000737:chemistry*; D008958:Models, Molecular; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D001993:Bronchodilator Agents; D009241:Ipratropium