Thermally activated structural phase transitions and processes in metal–organic frameworks

Abstract

The structural knowledge of metal–organic frameworks is crucial for understanding and developing new efficient materials for industrial implementation.

Synthetic and analytical considerations for the preparation of amorphous metal–organic frameworks

“…Thermal amorphisation, assumed to involve the breakage and reformation of M–L bonds (M = metal cation, L = organic ligand), is limited to certain MOFs because of the high enthalpy of crystallisation and structural reordering, relative to their low decomposition temperatures, T d . 34 The same challenge is observed with forming MQG, as the melting temperature, T m , of MOFs is often greater than their temperature of decomposition. Several a g MOFs are reported in the literature, with a large majority based on zeolitic imidazolate frameworks (ZIFs).…”

“…114 An interesting example of the Ostwald ripening in MOFs is the multimetal [Zn 1− x Co x (H 2 fipbb)] (H 2 fipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid)) which, after the nucleation of the needle-shape crystallites containing the Zn-SBU, ZnCo-SBU MOF shell grows around the Zn-SBU MOF core, generating a hole in the crystals. 172…”

“…33 Post-synthetic introduction of defects primarily utilises partial thermal decomposition of the linker, known as decarboxylation, whilst maintaining the parent MOF structure. 34 These defects were found to increase the number of accessible metal sites, resulting in improved catalytic activity and porosity. 35–37 Given that partial linker decarboxylation was observed with classical carboxylate linkers, common within MOF structures, this methodology could be applied to a wide range of materials.…”