Figure 1.

An example of (a) intrinsic topological flexibility in MIL-53(Al) and (b) intrinsic linker flexibility in CAU-13 is shown in the left and right parts of the figure, respectively. The particular linker type which is the main difference between both structures is highlighted in the figure. In both cases, the hypothetical free energy profile reveals two (meta)stable phases as a function of an order parameter that governs the transition between a close pore (cp) and a large pore (lp) phase: either a topology parameter (MIL-53) or a linker parameter (CAU-13).