A metallosupramolecular [Pd2L4](4+) cage can be cleanly converted into a [Pd2L2Cl4] metallo-macrocycle upon addition of chloride ions. The process is reversible, treatment of the [Pd2L2Cl4] macrocycle with silver(I) ions regenerates the [Pd2L4](4+) cage. Additionally, it is shown that guest molecules could be released on chloride triggered cage dis-assembly and taken up anew on re-assembly.

We describe the direct post-synthetic hydroxylation of UiO-66 through the photogeneration of hydroxyl radicals. Three approaches have been investigated, and levels of conversion up to 77% have been observed within 48 h.