Infrared and Raman spectra of DL ‐histidinium dinitrate and L ‐histidinium sulphamate

A comparative study of the infrared and Raman spectra of DL-histidinium dinitrate and L-histidinium sulphamate helps in determining the effect of hydrogen bonding in these crystals. The nitrate compound has a carboxylic group whereas the sulphamate compound has an ionized carboxyl group. However, the protonated imidazolium ring makes the histidine group in both cases ionic. Several group wavenumbers have been shifted in both molecules, indicating extensive hydrogen bonding. Some of the forbidden modes of the nitrate group have been observed. The removal of degeneracy of certain modes of both the nitrate and sulphamate anions suggests that the symmetry of both of these groups have been affected in their respective environments.