The metal-organic frame is well described in Wikipedia.

https://en.wikipedia.org/wiki/Metal–organic_framework

You can change the pore size by changing the parameters of hydrothermal synthesis (T, P, pH, concentration) or by the addition of surfactants.

Hi @ Nima Tabatabaei

i recommend the previous answer.

The synthesis of MOF is depended on the ligand, metal center and the nature of the solvent and the pH of the medium. Most of the previous literature were used the hydrothermal or the solvothermal method for the synthesis from the best of my knowledge. The metal has to be bind with the selected ligand and the application depends on the porosity of the synthsized material i.e. the efficiency towards adsorption or any kind of catalytic efficiency. The porosity of the material could be determined by the SEM study. So for the synthesis of MOF one must choose properly the ligand, metal, pH of the reaction mixture, temperature.

Regards

I am a bit confused about the answers, although they are correct.

For the question:

"How can I adjust the pore size without changing the metal and ligand?"

the answer must be simply: You basically CANNOT for a ridig linker (and most of the linkers so far used are rigid).

The size and shape of a rigid ligand together with the coordination are determining the maximum pore size, there are no synthesis parameters whatsoever than can change this.

E.g. if you use the rigid terephthalate as linker (ligand), the space between two metal atoms (ions) is rather fixed. For flexible linkers there is a lot of room for variation, see e.g. Article Construction of hierarchically porous metal-organic framewor...

But also for them, there is an upper limit given through the bonds and angles within the linker.