HYDRATION PROCESSES IN BIOLOGICAL AND MACROMOLECULAR SYSTEMS

I discuss several themes arising from the papers presented at this Far aday Discussion that are, in my view, particularly interesting and/or important. With respect to model systems, recent progress in understan ding structural aspects of the hydrophobic interaction, and of through -solvent interactions in general, is highlighted, together with the ne ed to continue to develop more sophisticated (theoretical and computat ional) interpretational techniques if we are to exploit to the full th e power of present-day experimental techniques. The current state of o ur knowledge of hydration effects on the structure and dynamics of bio molecules is discussed, and the importance of being able to see how mo lecular-level structural effects control behaviour at the important me soscopic level is underlined. Issues relating to recent progress in ch aracterising solvent effects in more complex systems and processes, in cluding those of industrial interest, are raised, and the necessity of using a range of appropriate experimental techniques when tackling su ch complex problems is stressed. Progress since the 1975 Royal Society Discussion is highlighted, and interesting issues ripe for fruitful d iscussion at this meeting are raised. A strong case can now be made th at our understanding of both the structure and dynamics of water as a function of its local environment is now sufficiently good to enable u s to use water as a probe of complex system behaviour, rather than, as heretofore, an object of study in itself.