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A history of Hydrophobic Interaction

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INTRODUCTION:
A) Hydrophobic Interaction: A History
Non-polar solutes in water experience a force that causes them to aggregate. This force is important for many biological and self-assembly processes, like the aggregation of amphiphilic lipids into bilayers (micelles and membranes). It also plays a dominant role in protein folding and association. Although, Hydrophobicity is a very commonly observed and explored concept, important for many chemical and biological phenomena, its molecular origin is far from being understood. There have been many theories and controversies for the past five or so decades, trying to come up with a suitable explanation to the problem of hydrophobicity and why it occurs.
Frank and Evan [1] , in 1945, observed that on mixing water with hydrophobic molecules, the enthalpy and entropy of the system is decreased. They suggested that this decrease may be due to the changes in the water structure near the non- polar solutes. In the words of Frank and Evan “when a rare gas atom or a non-polar molecule dissolves in water, at room temperature, it modifies the water structure in the direction of greater crystallinity- the water, so to speak, builds a microscopic cage around it.” This was the famous “iceberg” model. It has been emphasized though, that water structure is not exactly like an ice-cage but more like a clathrate cage formed in gas hydrates.
Figure 1: A clathrate cage containing a guest molecule. (shown here- Type II clathrates)
Later,

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