The metal−organic framework MIL-53(Al) serves as a model system in this study. Its formation mechanism in N,N-dimethylformamide (DMF) is elucidated through simultaneous FTIR and Raman spectroscopy and turbidity measurements collected under in-situ synthesis conditions in a custom-designed solvothermal reactor coupled with reaction sampling. Different synthesis steps are followed over synthesis time including a prenucleation building unit (PNBU) consisting of one linker molecule and one aluminum atom, the assembly of the PNBUs to MIL-53 nuclei in solution, the decomposition of DMF to formic acid and dimethylammonium, and finally the precipitation of the crystalline MOF phase. The rearrangement of the PNBU to form MIL-53 is identified as the rate-limiting reaction step responsible for the long induction time at low temperatures (<80 °C). MOF nucleation and particle growth is followed directly in-situ through a novel methodcomparison of the temporal evolution of the respective FTIR and Raman bands. Analysis of the particles isolated after various synthesis times indicates that MIL-53(H 2 BDC) of low crystalline long-range order is formed initially, which quickly rearranges to form more ordered, crystalline particles with DMF inside of the pores (MIL-53(DMF)). It is to be expected that the synthesis steps elucidated herein can be generalized to the solvothermal synthesis of other metal−organic framework structures from metal salts and organic acid linkers.

The novel MOF hcp UiO-66 is synthesized using the ionic liquid ([PBuMEE]2[BDC]) as a linker precursor.

A facile extrusion approach that can fully retain the breathing behavior of flexible metal-organic frameworks (MOF) like MIL-53 and MIL-53-NH 2 employing methyl cellulose as binder is reported. Shaped MOF extrudates were extensively characterized by nitrogen sorption, X-ray diffraction, thermogravimetric analysis and scanning electron microscopy. A detailed study on the mechanical stability of MIL-53 extrudates with different amounts of binder reveals an increase in stability at low binder fractions while the maximum in attainable stabil- [a] 4700 Figure 2. Powder X-ray diffraction patterns of produced MIL-53 extrudates with different amounts of MC 400 (left). Nitrogen adsorption isotherms at 77 K of the MIL-53 extrudates in comparison to the parent powder (right). Desorption branches are excluded for clarity.

The paper describes a method to induce the formation of MIL-68(Al) rather than MIL-53(Al) using a formic acid modulated synthesis approach.

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