The Microwave Response of Water as the Measure of Interactions in a Complex Liquid

Water is the universal solvent in nature. Does this imply, however, that its interaction with its environment is also a universal feature? While this question maybe too fundamental to be answered by one method only, we present evidence that in the broadening of dielectric spectra of water one can define universal features of dipolar interactions with different types of matrices. To explore this statement, we examine the dielectric spectrum of aqueous solutions of ions, monosaccharides, nucleotides, amino acids and finally proteins. In these systems the characteristic relaxation spectrum of bulk water can be described by the Cole-Cole (CC) function. The parameters of the CC function can be used to construct a new phenomenological phase space in which the evolution of the system can be traced as a trajectory, as a parameter such as the solute concentration is varied. The approach, first published in 2010 (Puzenko, A.; Ben Ishai, P.; Feldman, Y. Cole-Cole Broadening in Dielectric Relaxation and Strange Kinetics. Phys. Rev. Lett. 2010, 105), offers new insights into the dynamic of the relaxation and the organization of water in the solute hydration sphere.