Linker depletion for missing cluster defects in non-UiO metal-organic frameworks

Defect engineering is a valuable tool to tune the properties of metal-organic frameworks. However, defect chemistry remains still predominantly limited to UiO-type MOFs. We describe the preferential formation of missing cluster defects in heterometallic titanium-organic frameworks of the MUV-10 family when synthesised in sub-stoichiometric linker conditions. Our results show the value of integrating experimental work, computational modelling and thorough characterization in rationalizing the impact of defects over the porosity and structure of this family of materials. Correlation of experiment with computational models reveals the dominance of missing cluster vacancies in the pore size distribution of defective MUV-10. These same models were used to investigate the correlation of defects by synchrotron X-ray diffraction. The diffraction at low reflection angles is dominated by diffuse scattering that is indicative of short-range order and cannot be indexed to the defective structural models generated. In addition to the low atomic scattering factor of titanium, these results confirm the need for high-resolution electron microscopy methods for modelling nanoscale disorder in titanium MOFs.

Automated summary

Defect engineering is important for tuning the properties of metal-organic frameworks, with a focus on the preferential formation of missing cluster defects in heterometallic titanium-organic frameworks. Integration of experimental work, computational modeling, and thorough characterization helps rationalize the impact of defects on the porosity and structure of materials. Synchrotron X-ray diffraction reveals the dominance of missing cluster vacancies in defective structures, while high-resolution electron microscopy methods are needed to model nanoscale disorder in titanium MOFs.