Tag Archive: CMD26

Sep 08

Colloquium on Porous Frameworks: Day 2

Program Porous Frameworks ColloquiumOn Monday, we had the second day of our colloquium on Porous Frameworks, containing no less than 4 full sessions, covering all types of frameworks. We started the day with the invited presentation of Prof. Dirk De Vos of the KU Leuven, who discussed the breathing behavior in Zr and Ti containing MOFs, including the work on the COK-69 in which I was involved myself. In the MOFs presented, the breathing behavior was shown to originate from the folding of the linkers, in contrast to breathing due to the hinging motion of the chains in MIL-47/53 MOFs.

After the transition metals, things were stepped up even further by Dr. Stefania Tanase who talked about the use of lanthanide ions in MOFs. These lanthanides give rise to coordinated water molecules which appear to be crucial to their luminescence. Prof. Donglin Jiang, of JAIST in Japan, changed the subject to the realm of COFs, consisting of 2D porous sheets which, through Van Der Waals interactions form 3D structures (similar to graphite). The tunability of these materials would make them well suited for photoconductors and photoenergy conversion (i.e. solar cells).

With Prof. Rochus Schmid of the University of Bochum we delved into the nitty-gritty details of developing Force-Fields for MOFs. He noted that such force-fields can provide good first approximations for structure determination of new MOFs, and if structure related terms are missing in the force-field these will pop up as missing phonon-frequencies.

Prof. Monique Van der Veen showed us how non-polar guest molecules can make a MOF polar, while Agnes Szecsenyi bravely tackled the activity in Iron based MIL-53 MOFs from the DFT point of view. The row of 3 TU Delft contributions was closed by the invited presentation of Prof. Jorge Gascon who provided an overview of the work in his group and discussed how the active sites in MOFs can be improved through cooperative effects.

Prof. Jaroslaw Handzlik provided the last invited contribution, with a comparative theoretical study of Cr-adsorption on various silicate based materials (from amorphous silicate to zeolites). The final session was then closed by the presentations of Dr. Katrine Svane (Bath University) who discussed the effect of defects in UiO-66 MOFs in further detail and Marcus Rose presenting his findings on hyper-crosslinked Polymers, a type of COFs with an amorphous structure and a wide distribution in different pore sizes.

This brought us to a happy end of a successful colloquium, which was celebrated with a drink in the city center of Groningen. Tuesday we traveled back home, such that Wednesday Sylvia could start at the third part of the conference-holiday roller coaster by leaving for Saltzburg.

Sep 04

Colloquium on Porous Frameworks: Day 1

Program Porous Frameworks ColloquiumToday the CMD26 conference started in Groningen, and with its kick-off also our own 2-day colloquium on porous frameworks (aka MOFs, COFs and Zeolites) was launched. During the two sessions of the day, the focus mainly went out to the Zeolites, with Prof. Emiel Hensen of the Technical university of Eindhoven introducing us to the subject and discussing how new zeolites could be designed in a more rational way. He showed us how the template used during synthesis plays a crucial role in the final growth and structure. Dr. Nakato explained how alkali-metal nanoclusters can undergo insulator to metal transitions when incorporated in zeolites (it is due to the competition between electron-electron repulsion and electron-phonon coupling), while Dr. De Wijs informed us on how Al T-sites need to be ordered and assigned in zeolites to allow for the prediction of NMR parameters.

After the coffee break Dr. Palcic, from the Rudjer Boskovic Institute in Croatia, taught us about the role of heteroatoms in zeolites. She told us that even though more than 2 million theoretical structures exist, only 231 have officially been recognized as having been synthesized, so there is a lot more work to be done. She also showed that to get stable zeolites with pores larger than 7-8 Angstrom one needs to have 3 and 4-membered rings in the structure, since these lead to more rigid configurations. Unfortunately these rings are themselves less stable, and need to be stabilized by different atoms at the T-sites.

Dr. Vandichel, still blushing from his tight traveling scheme, changed the subject from zeolites to MOFs, in providing new understanding in the role of defects in MOFs on their catalytic performance. Dr. Liu changed the subject even further with the introduction of COFs and showing us how Hydrogen atoms migrate through these materials. Using the wisdom of Bruce Lee :

You must be shapeless, formless, like water. When you pour water in a cup, it becomes the cup. When you pour water in a bottle, it becomes the bottle. When you pour water in a teapot, it becomes the teapot.

he clarified how water behaves inside these porous materials. Our first colloquium day was closed by Ir. Rohling, who took us back to the zeolite scene (although he was comparing the zeolites to enzymes). He discussed how reactivity in zeolites can be tweaked by the confinement of the reacting agents, and how this can be used for molecule identification. More importantly he showed how multiple active site collaborate, making chemical reactions much easier than one would expect from single active site models.

After all was said and done, it was time to relax a little during the conference welcome reception. And now time to prepare for tomorrow, day 2 of our colloquium on porous frameworks.