Crown Ethers. From Serendipity to Design

Typically, in cases where some minor impurity is isolated instead of the expected product, the whole stuff is washed into the waste and the experiment repeated with purified reactants and greater control over the reaction conditions. If Pedersen had followed this pattern of behavior (especially because product 214 was unable to complex the cation and therefore useless from the viewpoint of the initial practical request ), he probably would never again have had the chance to go to Stockholm to receive the Nobel Prize subsequently awarded to him (together with Donald Cram and Jean-Marie Lehn) in 1987. Fortunately, peculiarities displayed by 214 did not escape Pedersen s attention. In fact, while ether 214 was only slightly soluble in methanol, its solubility increased dramatically in the presence of sodium hydroxide. Additional tests showed that this effect was not base dependent and could be observed with many sodium salts, as well as with many other salts of inorganic cations. Even more intriguing was the observation that inorganic salts which were 

The initial finding was made in 1962 and over the next five years the author devoted very intensive studies at elaborating the preparative methods and outlining the scope and ramifications of his discovery. As a result, his full publication in 1967 contained an in-depth description of a new phenomenon and opened an entry into an enormously huge area of exploration for hundreds of laboratories all over the worlda striking example of the ability of one outstanding chemist to create jobs for the entire chemical community  

Below we will concentrate our attention only at the main trends of molecular design that were based upon the original concept of macrocyclic binding. From the very beginning, the strategies of numerous investigations in this field were distinctly different. 

Now it seems appropriate to comment, at least very briefly, on one of the major reasons underlying the increased interest toward the various aspects of complexing phenomena. Why it is considered to be important to pursue studies 

Both in their general pattern of structure and mode of cation binding, 222 and 223, as well as many other naturally occurring ionophores, are similar to crown 

---