Thermodynamic model of inclusion process of alpha-cyclodextrin I have a question about thermodynamic model of inclusion process of CD, published by Tabushi (DOI: 10.1021/ja00471a043). Here, in 3rd step, action is described as: "An apolar solute (guest molecule) is transferred from water to the ideal gaseous state leaving a structured cavity behind. The cavity then collapses with redistribution of the water molecules." I don´t understand this part where guest molecule is transferred to the gaseous state (why this state). Can somebody try to explain this in some simple way if it is possible, please? Thanks for all the answers!
This is a variation on the application of Hess's Law (or looks like it, not having read the article). The idea is that the individual steps add up to the complete reaction 

cyclodextrin with included water + hydrated guest $\rightarrow$ hydrated cyclodextrin with included guest

According to Hess's Law you can break up this process into a sum of intermediate steps. One of those steps is dehydrating the guest molecules and shoving the waters into the bulk solvent. That last step is what is meant by collapse of the cavity  with redistribution of the water molecules..