Molecular Recognition with a Large Hydrophobic Component

4 Molecular Recognition with a Large Hydrophobic Component 

Log(Ka) for Various Hydrophobic Guests with Cyclodextrins in Water (298 K)  

The second cyclophane study we examine sheds light on the special nature of water. Is water absolutely unique as a solvent for molecular recognition Or, is the hydrophobic ef- 

The calixarenes (from the Greek calix, meaning chalice) are a family of structures that have seen extensive use in many contexts. Shown below is the remarkable, one-step synthesis of the prototype calixarene. This condensation reaction is a variant of the phenol-aldehyde condensation that produces bakelite, the first synthetic polymer. Early workers spent considerable effort to optimize this synthesis, biasing the product toward the calixarene 

Extensive studies of the conformational preferences of calixarenes have established certain shape preferences, and a view of the cone-shaped form that has found the most use in molecular recognition studies is shown below. It should be remembered, though, that without additional structural constraints that favor this form, a simple calixarene is conformationally mobile and exists in several different forms. 

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