Freeze-drying Fourier transform infrared attenuated total reflection spectroscopy of surface adsorbed layers. Water-assisted proton transfer in cytidine-5′-phosphoric acid

Abstract

The zwitterionic structure of cytidine-5′-phosphoric acid (5′-CMP) in the acid form has been studied by means of freeze-drying ATR spectroscopy. Surface deuteration and protonation studies of the hydrated sample were accomplished and some band assignments are made. The dependence of the proton transfer process in the zwitterionic CMP(H) on relative humidity is evidenced. The ability of the water molecules adsorbed on the thallium bromide iodide crystal to act as proton donors and the enhancement of the degree of dissociation of the adsorbed water are demonstrated.