In as ystematic investigation,t he synthesis of metal-organicf rameworks (MOFs) with MIL-140 structure was studied. The precursors of this family of MOFs are the same as for the formation of the well-known UiO-typeM OFs although the synthesis temperature for MIL-140 is significantly higher. This study is focused on the formationo fZ rbased MIL-140M OFs with terephthalic acid (H 2 bdc), biphenyl-4,4'-dicarboxylic acid (H 2 bpdc), and4 ,4'-stilbenedicarboxylic acid (H 2 sdc)a nd the introduction of synthesis field diagrams to discover parameters for phase-pure products. In this context, aM IL-140n etwork with H 2 sdc as linkerm ole-cule is first reported. Additionally,a ni mportanta spect is the reduction of the synthesis temperature to make MIL-140 MOFsm ore accessible even though linkersw ith am ore delicate nature are used.T he solvothermal syntheses were conductedi nh ighly concentratedr eactionm ixtures whereby a targeted synthesis to yield the MIL-140p hase is possible. Furthermore, the effect of the often-used modulator approachi se xamined for these systems. Finally, the characteristics of the synthesized MOFs are compared with physisorption measurements, thermogravimetric analyses, and scanning electron microscopy.

Solvent-assisted linker exchange was used as tool to modify a MIL-140D-sdc (sdc = 4,4′-stilbenedicarboxylate) MOF with azostilbene dicarboxylic acid. The azo groups can act as coordination sites for copper ions and allow the use of this material as sensor for gaseous H2S.

The selective detection of hydrogen sulfide (H 2 S) is an important task because of its potentially hazardous effects not only on the environment but also on human health. Here, we present the zirconium-based MOF-808, which was modified with copper salts, as a colorimetric sensor material for the visible, reversible and sensitive H 2 S detection at room temperature. The copper cations, which are incorporated in the oxidation state + II, are installed at the inorganic building units (IBUs) of the framework so that they are accessible for interactions with H 2 S. The activated copper doped MOF-808 powder shows significant and fast color change in the presence of H 2 S, which can be detected by UV-vis spectroscopy. Moreover, the detection process is reversible by heating the material to 120 °C under ambient conditions leading to its decolorization. The detection performance of the material was studied by in situ UV-vis measurements in a reaction chamber. The material was able to respond to 100 ppm H 2 S in several cycles of exposure and heating to 120 °C under moist air conditions in a defined wavelength range. This reversibility is very uncommon for copper-based H 2 S sensing reactions and highlights the potential of MOFs as selective sensing materials.