Discovery and Synthesis Optimization of Isoreticular Al(III) Phosphonate-Based Metal-Organic Framework Compounds Using High-Throughput Methods

I see the periodic table as a huge playground, and in our research, we focus on the synthesis of new materials, porous materials, such as this here, that’s a structural model, and we see holes in the framework, and that can be used to store molecules or also to separate molecules based off on the size of these. And in addition to that kind of studies, we also develop new reactor systems in order to accelerate the discovery process. The current experimental challenges are to further accelerate the synthesis and characterization process with additional high throughput instrumentation, such as high throughput absorption characterization device.

The leg of detail and publications regarding the synthesis and characterization procedure affecting reproducibility is a well known problem in chemistry. By providing a thorough description of our method and setup, we aim to encourage other groups to adopt the described methodology, thereby increasing the reproducibility of experimental studies. We do not know what the future will bring, since we work on the discovery of new materials, and we never know what kind of properties these materials will have.

Nevertheless, I think that the use of linker molecules from renewable feedstocks will play a major role. And regarding the application, the use in sensing and the separation of gas molecules will be very important. To begin, add the linker H4PMP as a solid to the polytetrafluoroethylene or PTFE inserts, for Aluminum-CAU-60.

Then use a pipette to add the aluminum chloride solution, demineralized water, and the solution of additives to the inserts. Insert the discs into the sample plate and place the filled PTFE inserts into the sample plate. Mark the ground plate of the reactor in a way that allows the identification of the PTFE inserts.

And insert the sample plate with the filled PTFE inserts into the ground plate. Prepare two PTFE sheets and place them on the sample plates ensuring full coverage. Ensure that the PTFE sheet is correctly positioned and fits the head plate using the guide pins.

Add the screws and tighten them by hand. Then seal the initially-closed reactor with the help of a mechanical or hydraulic press and tighten the screws by hand again. Place the multiclave in a programmable forced convection oven.

For Aluminum-CAU-60, set the temperature time program shown on the screen. Then start the temperature time program. Remove the multiclave from the oven once it cools down to room temperature.

Place it on a mechanical or hydraulic press and gently compress it until the screws can be loosened by hand. Place the multiclave inside a fume hood and remove the head plate of the reactor. Then remove the PTFE sheets and the sample plate with the PTFE inserts from the ground plate of the reactor.

Now, assemble the high throughput filtration block by connecting the filter block to a vacuum pump via two wash bottles. Place two filter papers between two silicone ceiling mats with the corresponding recesses in the filter block. Then place the PTFE filling block on top, ensuring that the appropriate recesses match the ceiling mats and the filter block.

Tighten the layers using the clamping frame, which is held in place by six stud bolts. To properly seal the unit, use wing nuts on the stud bolts and tighten them by hand. Close the recesses of the filling block that are not to be filled with plugs.

Turn on the membrane vacuum pump and set it to a mode in which it will pump down to the best possible vacuum. Transfer the contents of the PTFE inserts into the designated wells of the filling block with disposable pipettes. Once all the inserts are empty, take a second look for crystals and isolate them if present.

Carefully disassemble the filtration block once all the wells are drained. A product library is now available on filter paper. Allow it to air dry inside the fume hood.

Place the product library between the base plate and the cover plate to characterize the obtained product by powder X-ray diffraction later. Ensure that the recesses and the plates match the product locations. After aligning the plates, secure them with two screws.

Insert the product library into the sample holder of the defractometer. Carefully place the loaded sample holder into the XY stage of the defractometer. Close the instrument before starting the measurements.

The parameter space is shown in this figure. The synthesis with sodium hydroxide as an additive are highlighted in blue, the synthesis with no additive are highlighted in green, and the synthesis with the additive hydrochloric acid are highlighted in orange and red. The molar ratios of the reagents are shown on the left side and on the top.

The stacked plot of all the measured powder X-ray diffraction patterns is shown in this figure. Here, the additive sodium hydroxide is highlighted in blue, no additive is highlighted in green, and the additive hydrochloric acid is highlighted in red. The sample names are shown here, which correlate to the molar ratios of the starting materials used in the synthesis mixture.

These results suggest that the products with low crystallinity were obtained from the synthesis, where the molar ratio of sodium hydroxide to aluminum was one to one, or no sodium hydroxide or hydrochloric acid was present. Products of higher crystallinity were obtained from synthesis where hydrochloric acid was used as an additive.