Infrared spectra of isotopic polyglycines

For infrared absorption measurements, the following five isotopic polyglycines have been prepared: ordinary polyglycine (—NHCH₂CO—)_n, N-deuterated polyglycine (—NDCH₂CO—)_n, C-deuterated polyglycine (—NHCD₂CO—)_n, completely deuterated polyglycine (—NDCD₂CO—)_n, and N¹⁵-substituted polyglycine (—¹⁵NHCH₂CO—)_n. Infrared spectra have been observed both in the I and II forms of each of these five isotopic polyglycines in the spectral region of 4000–300 cm.^?1. On the basis of the comparison of these spectra with each other, a nearly complete set of assignments of the observed bands of polyglycines has been given.