Hydrogen Bond Effect on the Raman Shift of theCarbonyl Stretching Mode of Various Amide Solutions
✍ Scribed by Ying-Te Lee
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 476 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0377-0486
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✦ Synopsis
The Raman spectra of the CxO stretching mode of formamide, N-methylformamide and N,Ndimethylformamide mixed with various solvents were systematically studied as a function of concentration. It was found that the hydrogen bond e †ect plays an important role in reducing the carbonyl stretching wavenumbers for both isotropic and anisotropic vibrational modes. By interpreting the results of Raman shifts through the dilution e †ect and hydrogen bond-forming and -breaking e †ects, the relative strengths of various amide-amide and amidesolvent hydrogen bonds were determined. The results also indicated that the anisotropic vibrational wavenumbers are more sensitive to the hydrogen bond e †ect than to the dilution e †ect. Moreover, it was found that stronger hydrogen bond formation will decrease the non-coincidence values of the CxO stretching mode, as has been suggested elsewhere. Both the theoretical predictions based on LoganÏs model and the qualitative interpretations are discussed in analyzing the non-coincidence values of the CxO stretching modes of di †erent solutions.