We further prove the robustness of the MOF-CVD process by demonstrating this time for MAF-6, a large pore MOF. The CVD process is based on the reaction of ZnO with 2-ethylimidazole vapor at temperatures ≤ 100 °C. A combination of PALS and Kr physisorption measurements confirmed the porosity of these MOF-CVD films and the size of the MAF-6 supercages (diam. ~2 nm), in close agreement with powder data and calculations.
In collaboration with Prof. Coclite's lab at TU Graz, we report the solvent-free powder synthesis and thin film CVD of a crystalline coordination polymer obtained from the reaction of ZnO with a vaporized bipyridyl-triazole linker. The article can be accessed here.
Following the proof-of-concept work on the chemical vapor deposition of metal-organic frameworks (MOF-CVD) and a demonstration of its potential in microelectronics integration, we now present the fully cleanroom-compatible process for the deposition of large-area MOFs. Led by Alex, the output of this international collaboration was recently published in Chemistry of Materials. In this work, we thoroughly discussed the optimization process and unraveled the mechanism of MOF-CVD which led to a process chart—a guiding paradigm in developing future MOF-CVD formulations.
This marks an important milestone in bringing MOFs a step closer to the industrial-scale microfabrication lines and the production of MOF-based devices.
Although generally stable, ZIFs can undergo post‐synthetic linker exchange (PSLE) in solution under mild conditions. In this work, Joao led an international team of researchers and reported this novel, solvent‐free approach to post‐synthetic linker exchange through exposure to linker vapor. The paper can be accessed here or on the Publications page of our website.
Collaborative work on the role of structural defects in the adsorption and separation of C3 hydrocarbons in Zr-fumarate-MOF (MOF-801) is now published in ACS Chemistry of Materials. Led by Llwellyn's Group in Marseille, this work was made possible by the Marie Skłodowska-Curie Action Innovative Training Network, DEFNET (DEFect NETwork Materials Science and Engineering), a trans-European consortium of 9 academic institutions and 7 partner organizations. We are happy to be part of this collaboration!
Our Cu-MOF-CVD paper, entitled, "Vapour-phase deposition of oriented copper dicarboxylate metal-organic framework thin films", is ChemComm's front cover for September 2019 (68) issue.
Our work on the vapor-deposited zeolitic imidazolate frameworks as gap-filling ultra-low-k dielectrics has now been published in Nature Communications. Here we report a strategy for the integration of metal-organic frameworks (MOFs) as gap-filling low-k dielectrics in advanced on-chip interconnects. The proposed strategy is validated for thin films of the zeolitic imidazolate frameworks ZIF-8 and ZIF-67, formed in 2-methylimidazole vapor from ALD ZnO and native CoOx, respectively. Both materials show a Young’s modulus and dielectric constant comparable to state-of-the-art porous organosilica dielectrics.
The paper is accessible via an open-access platform through this link.
Together with the groups of Prof. Paolo Falcaro and Prof. Roland Resel (TU Graz, Austria), we expanded the scope of materials for MOF-CVD with Cu-MOF thin films. The orientation (crystallinity) was investigated by synchrotron measurements at the European Synchrotron Radiation Facility. Our study was accepted for publication in ChemComm.
Following a typical MOF-CVD protocol thin Cu and CuO precursor layers were deposited from the vapor phase and subsequently reacted with vaporized 1,4-benzenedicarboxylic acid (H2BDC) or trans-1,4-cyclohexanedicarboxylic acid (H2CDC). The resulting CuBDC and CuCDC films have an out-of-plane orientation with pore channels perpendicular to the surface, hence readily accessible for guest molecules as shown by QCM measurements.
UiO-66 is known as one of the most robust metal-organic framework materials. Nevertheless, UiO-66 has also been shown to undergo post-synthetic exchange of structural linkers with surprising ease in some solvents. To date, the exchange mechanism has not yet been fully elucidated. Here, we show how time-resolved monitoring grants insight into the selected case of exchanging 2-minoterephthalate into UiO-66 in methanol. Analysis of both the solid and liquid phase, complemented by computational insights, revealed the active role of methanol in the creation and stabilization of dangling linkers. Similar to monocarboxylate defects that can be introduced during UiO-66 synthesis, such dangling linkers undergo fast exchange. The presence of missing linker or missing cluster defects at the start of the exchange process was shown to have no considerable impact on the equilibrium composition. After the exchange process, the incoming 2-aminoterephthalate and remaining terephthalate linkers were distributed homogeneously in the framework for the typical sub-micron size of UiO-66 crystallites.
We are grateful to the concerted efforts from the excellent researchers of Ghent University and National Institute of Chemistry in Slovenia! Online version of the paper can be accessed here.
Review on Porous Organic and Carbon-based films
Our review paper on Bringing Porous Organic and Carbon‐Based Materials toward Thin‐Film Applications was accepted in Advance Functional Materials. Porous materials have attracted tremendous scientific and industrial interest due to their broad commercial applicability. However, some applications require that these materials are deposited on surfaces to create thin films. In this review, the recent progress of new porous thin‐film material classes is described: porous organic molecular materials, porous organic polymers, covalent organic frameworks, and nanoporous carbon. In each case, the state of the art and current barriers in their thin‐film fabrication, as well as intrinsic material advantages that are suited for different applications are presented. By highlighting the unique structural characteristics and properties of these materials, it is hoped that increased research development and industrial interest will be fostered, which will lead to new methods of thin‐film synthesis and consequently to new applications.
This work was a successful collaboration with several european research groups.