Exploring Functional Photonic Devices made from a Chiral Metal-Organic Framework Material by a Multiscale Computational Method

Electronic circular dichroism is an important optical phenomenon offering insights into chiral molecular materials. On the other hand, metal-organic frameworks (MOFs) are a novel group of crystalline porous thin-film materials that provide tailor-made chemical and physical properties by carefully selecting their building units. Combining these two aspects of contemporary material research and integrating chiral molecules into MOFs promises devices with unprecedented functionality. However, considering the nearly unlimited degrees of freedom concerning the choice of materials and the geometrical details of the possibly structured films, we urgently need to complement advanced experimental methods with equally strong modeling techniques. Most notably, these modeling techniques must cope with the challenge that the material and devices thereof cover size scales from {\AA}ngstr\"oms to mm. In response to that need, we outline a computational workflow that seamlessly combines quantum chemical methods to capture the properties of individual molecules with optical simulations to capture the properties of functional devices made from these molecular materials. We concentrate on chiral properties and apply our work to UiO-67-BINOL MOFs, for which experimental results are available to benchmark the results of our simulations and explore the optical properties of cavities and metasurfaces made from that chiral material

Entwicklung eines Werkzeugs und des Prozesses für das automatisierte Schaben von Metalloberflächen

Das Schaben ist ein Verfahren zur Bearbeitung metallischer Oberflächen und wird bislang ausschließlich manuell angewendet. Der Beitrag handelt von der Entwicklung eines Werkzeugs und des Prozesses für das Schaben von Metalloberflächen. Das im Rahmen eines Forschungsprojekts entwickelte Vorsatzwerkzeug zum Anbau an eine standardisierte CNC-Fräsmaschine bietet unter der Verwendung eines ebenfalls entwickelten Softwaretools die Möglichkeit das Verfahren unabhängig von spezialisierten Fachkräften durchführen zu können. Des Weiteren kann durch die Automation des Verfahrens eine höhere Produktivität realisiert werden. Der Beitrag geht neben dem aktuellen Stand der Technik intensiv auf die Eigenschaften des Vorsatzwerkzeugs, die Entwicklung eines notwendigen spezifischen Softwaretools sowie auf die Qualifizierung des Systems ein. Abschließend werden die gewonnen Ergebnisse in die Thematik eingeordnet und weiteres Forschungspotential ausgewiesen

Entwicklung eines Werkzeugs und des Prozesses für das automatisierte Schaben von Metalloberflächen

Das Schaben ist ein Verfahren zur Bearbeitung metallischer Oberflächen und wird bislang ausschließlich manuell angewendet. Der Beitrag handelt von der Entwicklung eines Werkzeugs und des Prozesses für das Schaben von Metalloberflächen. Das im Rahmen eines Forschungsprojekts entwickelte Vorsatzwerkzeug zum Anbau an eine standardisierte CNC-Fräsmaschine bietet unter der Verwendung eines ebenfalls entwickelten Softwaretools die Möglichkeit das Verfahren unabhängig von spezialisierten Fachkräften durchführen zu können. Des Weiteren kann durch die Automation des Verfahrens eine höhere Produktivität realisiert werden. Der Beitrag geht neben dem aktuellen Stand der Technik intensiv auf die Eigenschaften des Vorsatzwerkzeugs, die Entwicklung eines notwendigen spezifischen Softwaretools sowie auf die Qualifizierung des Systems ein. Abschließend werden die gewonnen Ergebnisse in die Thematik eingeordnet und weiteres Forschungspotential ausgewiesen

Utilizing Machine Learning to Optimize Metal-Organic Framework-Derived Polymer Membranes for Gas Separation

Metal-organic frameworks (MOFs) have gained substantial attention as promising materials for gas separation membranes due to their exceptional porosity, tailorability, and functionalizability. In this study, we present a novel approach to further enhance the properties of porous polymer membranes emerging from MOFs through crosslinking of the organic linker molecules and subsequent metal-atom removal. To ensure reproducibility of the multi-step synthesis process and high quality of the resulting polymeric membranes, we automated the process and followed a machine learning optimization approach. The high-quality MOF-thin films (SURMOFs) were prepared in a layer-by-layer fashion directly on gold-coated porous alumina substrates. This direct synthesis proved crucial to preserve the structural integrity of the membranes and thus avoiding defect formation caused by a substrate-transfer process, which is usually required when advanced materials are used to fabricate a membrane. The initial SURMOF membrane exhibits moderate gas separation performance, once crosslinked, its gas selectivity could be significantly enhanced although with the compromise of lower gas permeance. Interestingly, once we removed the metal centers and thereby converted the SURMOF into a purely organic polymeric membrane, the membrane gas permeance could be restored almost to its initial condition while preserving the enhanced selectivities. In particular, the resulting polymeric membrane outperforms most commercially available polymer membranes for H2 /CO2 gas separation. This research outlines a promising approach to employ MOFs as template in the generation of advanced polymer membranes for various gas and liquid phase separation applications

Post‐synthetic modification of DUT‐5‐based metal organic frameworks for the generation of single‐site catalysts and their application in selective epoxidation reactions

New single‐site catalysts based on mixed‐linker metal‐organic frameworks with DUT‐5 structure, which contain immobilized Co$^{2+}$, Mn$^{2+}$ and Mn$^{3+}$ complexes, have successfully been synthesized via post‐synthetic modification. 2,2’‐Bipyridine‐5,5’‐dicarboxylate linkers were directly metalated, while 2‐amino‐4,4’‐biphenyldicarboxylate linkers were post‐synthetically modified by their conversion to Schiff‐base ligands and a subsequent immobilization of the metal complexes. The resulting materials were used as catalysts in the selective epoxidation of $\it trans$‐stilbene and the activities and selectivities of the different catalysts were compared. The influence of various reaction parameters on conversion, yield and selectivity were investigated. Very low catalyst amounts of 0.02 mol % were sufficient to obtain a high conversion of $\it trans$‐stilbene using molecular oxygen from air as the oxidant. For cobalt‐containing MOF catalysts, conversions up to 90 % were observed and, thus, they were more active than their manganese‐containing counterparts. Recycling experiments and hot filtration tests proved that the reactions were mainly catalyzed $\it via$ heterogeneous pathways

Sunlight exposure exerts immunomodulatory effects to reduce multiple sclerosis severity

Multiple sclerosis (MS) disease risk is associated with reduced sunexposure. This study assessed the relationship between measures of sun exposure (vitamin D [vitD], latitude) and MS severity in the setting of two multicenter cohort studies (n(NationMS) = 946, n(BIONAT) = 990). Additionally, effect-modification by medication and photosensitivity-associated MC1R variants was assessed. High serum vitD was associated with a reduced MS severity score (MSSS), reduced risk for relapses, and lower disability accumulation over time. Low latitude was associated with higher vitD, lower MSSS, fewer gadolinium-enhancing lesions, and lower disability accumulation. The association of latitude with disability was lacking in IFN-beta-treated patients. In carriers of MC1R:rs1805008(T), who reported increased sensitivity toward sunlight, lower latitude was associated with higher MRI activity, whereas for noncarriers there was less MRI activity at lower latitudes. In a further exploratory approach, the effect of ultraviolet (UV)-phototherapy on the transcriptome of immune cells of MS patients was assessed using samples from an earlier study. Phototherapy induced a vitD and type I IFN signature that was most apparent in monocytes but that could also be detected in B and T cells. In summary, our study suggests benefidal effects of sun exposure on established MS, as demonstrated by a correlative network between the three factors: Latitude, vitD, and disease severity. However, sun exposure might be detrimental for photosensitive patients. Furthermore, a direct induction of type I IFNs through sun exposure could be another mechanism of UV-mediated immune-modulation in MS