Amorphization of metal-organic framework MOF-5 at unusually low applied pressure

So far, amorphization of solid materials at ambient temperature required a high pressure (several gigapascal). This raises an important question: is it possible to induce amorphization of solid materials by a low pressure at ambient temperature? Herein, our x-ray diffraction measurements demonstrated that ${\text{Zn}}_4\text{O}{\left(\text{BDC}\right)}_3$ metal-organic framework (MOF-5) can be irreversibly amorphized at ambient temperature by employing a low compressing pressure of 3.5 MPa, which is 100 times lower than that required for amorphization of other solids. This was further supported by the collapse of pores. Furthermore, the Raman spectra indicated that the irreversible pressure-induced amorphization (PIA) was due to the destroying of some carboxylate groups. One can conclude that the availability of thousands of MOFs can allow ones to reveal relationships between structures and PIA at a low pressure.

Figure 1

(Color online) Calculation model for MOF-5.

Figure 2

(Color online) (a) Cubic crystalline MOF-5 and (b) XRD patterns of MOF-5 subjected to compressing treatments at room temperature with various pressures from 0.0 to 10.3 MPa (the original sample is MOF-5 without the treatment).

Figure 3

(Color online) Surface areas of MOF-5 subjected to compressing treatments at room temperature with various pressures from 0.0 to 10.3 MPa (BET and Langmuir surface areas are the surface areas calculated by using BET equation and Langmuir equation, respectively).

Figure 4

(Color online) Raman spectra of (a) crystal MOF-5 and (b) amorphous MOF-5 formed via compression at 10.3 MPa at room temperature.

Figure 5

(Color online) TGA curves of (a) crystal MOF-5 and (b) amorphous MOF-5 formed via compressing treatment at room temperature with a pressure of 10.3 MPa.