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Ionophores.

This page shows some interactive JSmol views of two ionophore complexes; sodium with monensin A and potassium with valinomycin. These can transport Na⁺ or K⁺ across lipid membranes.

The first view shows the sodium complex of monensin A. The Na⁺ ion is coloured purple and hydrogen bonds are shown as dashed red bonds. The sodium ion is 7-coordinate, bonded to hard oxygen donors. The ligand is wrapped around the ion and the wrapping is supported by the hydrogen bonding - both intramolecular and involving two water molecules.

The space-filling view emphasises the ability of the ligand to "hide" the positively charged ion from the environment. Note that aliphatic groups lie on the outside of the complex.

Valinomycin complexes a K⁺ ion in a 6-coordinate site. Again, all the donors are oxygen, the conformation is supported by hydrogen bonding, and there are aliphatic groups around the outside.

The spacefilling view shows the potassium cation inside a "barrel-shaped" host ligand.


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