The T, p-dependence of the chemical shift of the hydroxyl protons in deeply supercooled methanol and water

The hydroxyl proton chemical shifts delta ((H) under bar - O) of supercoole d methanol (T-min = 149 K) and water have been determined (T-min = 183 K), and the pressure dependence of these shifts was measured up to 200 MPa. In both compounds the downfield shift of delta ((H) under bar - O) continues d own to the lowest temperatures reached. This result disagrees with the two state models for the hydrogen bond formation in both liquids. The isotherms delta ((H) under bar(2)O) show for T less than or equal to 273 K an upfiel d shift that becomes more pronounced with decreasing temperature. For delta ((H) under bar - O - CH3), increasing p causes at all temperatures a downs hift.