Water: From Clusters to the Bulk

Abstract

Water is of fundamental importance for human life and plays an important role in many biological and chemical systems. Although water is the most abundant compound on earth, it is definitely not a simple liquid. It possesses strongly polar hydrogen bonds which are responsible for a striking set of anomalous physical and chemical properties. For more than a century the combined importance and peculiarity of water inspired scientists to construct conceptual models, which in themselves reproduce the observed behavior of the liquid. The exploration of structural and binding properties of small water complexes provides a key for understanding bulk water in its liquid and solid phase and for understanding solvation phenomena. Modern ab initio quantum chemistry methods and high-resolution spectroscopy methods have been extremely successful in describing such structures. Cluster models for liquid water try to mimic the transition from these clusters to bulk water. The important question is: What cluster properties are required to describe liquid-phase behavior?

UV Resonance Raman Determination of Molecular Mechanism of Poly(N-isopropylacrylamide) Volume Phase Transition

“…The formation of these water clusters is highly cooperative, e.g. cooperative effects in a water pentamer cluster result in hydrogen bonds energies that are almost twice as large as the linear hydrogen bonded dimer 90. Presumably, by providing a nucleation site the amide bond lowers the free energy barrier to formation of large water clusters.…”

17O NMR Investigation of Water Structure and Dynamics

“…1–3 Accordingly, there have been many NMR studies of H 2 O and they generally involve 1 H spectroscopy, but the resolution in these experiments is often not high for a number of reasons. Two other approaches to studying water involve either 2 H or 17 O NMR spectroscopy.…”

Removing endotoxin from metallic biomaterials with compressed carbon dioxide-based mixtures

“…Consequently, the endotoxin attenuation after CO 2 -water treatment was most likely due to endotoxin removal. It is believed that water acted as a co-solvent, increasing important bulk properties for solvation in CO 2 such as the dielectric constant and polarity [29–31], thus enhancing endotoxin removal. For instance, the dielectric constant for the mixture of CO 2 and water will be 2.46, whereas for pure CO 2 at the same conditions is 1.59.…”