Isomer selective infrared spectroscopy of supersonically cooled cis- and trans-N-phenylamides in the region from the amide band to NH stretching vibration

• Published in: Physical chemistry chemical physics : PCCP Vol. 11; no. 29; pp. 6098 - 6106
• Main Authors: MIYAZAKI, Mitsuhiko, SAIKAWA, Jiro, ISHIZUKI, Hideki, TAIRA, Takunori, FUJII, Masaaki
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.01.2009
• Subjects: Acetanilides - chemistry; Chemistry; Electrons; Exact sciences and technology; Formamides - chemistry; General and physical chemistry; Isomerism; Molecular Conformation; Spectrophotometry, Infrared - methods; Infrared spectrometry; Depletion; Vibration; Substitution; Hydrogen; Methyl group; Frequency; Infrared spectrum; Isomer
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/b822310f

We measured the infrared (IR) spectra of supersonically cooled N-phenylformamide (formanilide) and N-phenylacetamide (acetanilide) in the amide band and X-H stretch vibration regions by using IR-UV depletion spectroscopy combined with a newly developed mid-IR light source based on difference frequency generation in ZnGeP(2). The two rotational isomers, cis- and trans- of the amide group were separately monitored to record the IR spectra. Both of the conformers showed similar features in the amide I and II regions, while major differences of the isomers appeared in the amide III vibration region. The IR spectrum of trans-acetanilide closely resembles that of trans-formanilide, except for vibrations of the methyl group; that is, substitution of the formyl hydrogen to a methyl group has only a minor effect on the amide vibrations.