Crown Ethers, lonophores, and the Solvation of Metal Ions

3 CROWN ETHERS, lONOPHORES, AND THE SOLVATION OF METAL IONS 

Such interactions are even better when one metal cation can interact with several lone pairs on heteroatoms in the same molecule. Species that can do this are known as bidentate, tridentate. 

Naturally occurring lipid-soluble molecules that are able to transport ions across cell membranes are called ionophores (ion carriers, Greek c )6p(0, phew, to carry), and they play numerous critical roles in biology. They encase metal ions in a mainly hydrocarbon shell, and this allows them to pass through lipid membranes. Sometimes, as with the puffer fish toxin, tetrodotoxin, 4.28, this means that they are very toxic, as they upset the normal ion balance within cells. In other cases, as with amphotericin B, 4.29, there is a medicinal use although it is quite toxic, it can be used in low doses to treat the protozoan infection leishmaniasis. 

Christmas crackers are popular in the United Kingdom and Ireland and some Commonwealth countries they consist of a cardboard tube wrapped in paper, which is pulled with a small bang like a cap gun, at the start of a holiday meal. Inside is a gift and a rather foolish looking paper crown, which is supposed to be worn for the rest of the meal. 

Alcohols are named from the longest chain bearing the OH group. The suffix is -ol. Several schemes are available for naming ethers. 

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