On the CD2 probe infrared method for determining polymethylene chain conformation

M. Maroncelli, H. L. Strauss, R. G. Snyder

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


The rocking mode frequency of a CD2 group substituted in a polymethylene chain is sensitive to conformation in the immediate vicinity of the CD2 group. This sensitivity forms the basis of a commonly used infrared method for determining site-specific conformation in polymethylene systems. In the present work, the CD2 probe method has been extended and quantified with the use of infrared data on model CD2-substituted n-alkanes. The frequency of the CD2 rocking band is determined primarily by the conformation of adjoining CC bonds, i.e., by tt, gt, and gg pairs. However, we have found that there are significant frequency shifts associated with other factors. These include the conformation of the next nearest CC bonds, both with the CD2 positioned at the end and in the interior of the chain, and chain length. In addition, the ratio of the absorptivities of the tt to gt bands has been established. These results enable the method to provide new details about the conformation of the chains in polymethylene systems and reliable estimates of the concentrations of specific kinds of short conformational sequences.

Original languageEnglish (US)
Pages (from-to)4390-4395
Number of pages6
JournalJournal of physical chemistry
Issue number20
StatePublished - 1985

All Science Journal Classification (ASJC) codes

  • General Engineering
  • Physical and Theoretical Chemistry


Dive into the research topics of 'On the CD2 probe infrared method for determining polymethylene chain conformation'. Together they form a unique fingerprint.

Cite this