l-Histidine sulfates

In the l-His + H2SO4 + H2O system, in addition to known 2l-His·2H2SO4·3H2O and l-His·H2SO4 crystals, new crystalline compounds 2l-His·H2SO4·H2O and 2l-His·H2SO4 have been obtained. The better quality of 2l-His·H2SO4·H2O allowed determining its crystal structure. IR and Raman spectra of the crystals are shown and discussed. The crystals of l-histidine sulfates are not noticeable by their nonlinear optical properties.