Structural basis for the discrepancy of spectral behavior in C-H stretching band between steroids and long chain hydrocarbon compounds

Yizhuang Xu, Jing Tao, Zhenhua Xu, Shifu Weng, Jianping Xu, R. D. Soloway, Jinguang Wu, Duanfu Xu, Guangxian Xu

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

The discrepancies of the spectral behavior for the C-H stretching band between some long chain hydrocarbon compounds and steroids were investigated. At low temperature, the C-H stretching bands exhibit complex fine structure in steroids but remain simple in long chain hydrocarbon compounds. MM3 molecular mechanics calculation indicates that, for long chain hydrocarbon compounds, the C-H groups vibrate with large scale coupling. There exist a few bands where the C-H groups vibrate in synchronous and inphase mode. Thus the variations of dipole moment for these bands are enhanced and the intensities are obviously stronger than others and cover other band in the spectra. This is just the reason why the C-H stretching bands are simple even at low temperature environment. Nevertheless, for the steroids, the C-H stretching bands vibrate with local coupling mode. The synchronous enhancement effect does not occur, the differences of intensities for various modes are not as large as those in long chain hydrocarbon compounds. Hence the fine spectral structure could be observed in cryogenic FT-IR spectra. The structural basis for the above phenomenon is that the C-H groups in long chain hydrocarbon compound exist in the similar microenvironment, while the C-H group occurred in different microenvironment for steroids.

Original languageEnglish (US)
Pages (from-to)178-184
Number of pages7
JournalScience in China, Series B: Chemistry
Volume42
Issue number2
DOIs
StatePublished - Apr 1999

Keywords

  • C-H stretching band
  • FT-IR
  • Molecular mechanics
  • Steroid

ASJC Scopus subject areas

  • Chemistry(all)

Fingerprint Dive into the research topics of 'Structural basis for the discrepancy of spectral behavior in C-H stretching band between steroids and long chain hydrocarbon compounds'. Together they form a unique fingerprint.

  • Cite this