Vibrational spectra and assignments of histamine dication in the solid state and in solution

The infrared and Raman spectra of histamine dihydrochloride and its N-deute rated derivative were recorded in the solid state. Raman spectra of samples dissolved in both normal and heavy wafer were also obtained. A general ass ignment of the fundamental vibrations of this cationic species of the hista mine molecule was proposed on the basis of the isotopic shifts and correlat ions with similar molcules. Wavenumber assignments to the imidazole stretch ing vibrations indicate a small increase in the ring electronic density wit h respect to histamine monocation, although the isotopic shifts involved le ad to some differences between the two sets of normal modes. The deviations observed on comparing the Raman spectra of solid and dissolved histamine d ication are not significant, agreeing with the fact that the two inidazole nitrogen sites are occupied. Copyright (C) 2000 John Whey & Sons, Ltd.