Terahertz Spectral Investigation of L-Cysteine Hydrochloride and its Monohydrate

Although terahertz waves are susceptible to water of crystallization (bound water), we found that the absorption spectra cysteine hydrochloride (LCH) and its monohydrate (LCHM) highly similar. To explain this particular phenomenon, density functional theory (DFT) independent gradient model (IGM) were used obtain vibration mode intermolecular interaction LCH LCHM. The molecular polarities LCHM then obtained by calculating their polarity index (MPI). characteristic peak positions in basically corresponded, with superimposed interference modes van der Waals between molecules concealing expression hydrogen bonds produced bound spectrum. In addition, intensity peaks spectrum was higher because polarity. general, analysis method combining THz-TDS MPI provides a new theoretical reference for studying relationship biomolecules water.