A while ago I wrote a lot about Prussian blue the wonder solid which captures cesium, the fact that people want to read what I write about Prussian blue made me think about the other inorganic ion exchange solids. One important one is the 2D network of zirconium hydrogen phosphate.
This can be quite simple to make, one synthesis is simply boiling together a zirconyl salt with phosphoric acid. This forms a layered solid which contains hydrogen phosphate groups, the hydrogen phosphate groups can be deprotonated and then cations can bind to the solid. One important person in this field is Abraham Clearfield who has written many papers on the subject of this class of solid. (Brian M. Mosby, Agustín Díaz and Abraham Clearfield, Dalton Trans., 2014, 43, 10328-10339).
Here we can see one of the layers in the solid it is a 2D network of zirconium atoms and hydrogen phosphate groups.
The 2D sheets then make a layered solid with many many layers. Here are some pictures of the layers of the solid.
When the zirconium phosphate is immersed in a solution of a metal some of the protons in the hydrogen phosphate groups can be replaced with metal ions, for example in the following diagram the layers in a potassium exchanged zirconium hydrogen phosphate can be seen.
Again the layers can be seen
We will have a look at some other interesting solids soon,