@article{63883, abstract = {{Proton exchange membranes (PEMs) are essential for fuel cells, yet conventional materials like Nafion suffer from humidity dependence and limited thermal stability. This study introduces sulfonated phenylene-bridged periodic mesoporous organosilicas (PMOs) as promising inorganic–organic hybrid PEMs, synthesized via surfactant-templating with varying alkyl chain lengths for different mesopore sizes. Post-synthetic functionalization involves nitration of phenylene moieties, reduction to amines, and ring-opening of propane or butane sultones to graft sulfonic acid groups via flexible spacers, achieving homogeneous distribution along pore walls. Post-functionalization is confirmed by powder X-ray diffraction (PXRD), revealing preserved 2D hexagonal p6mm ordering and phenylene stacking. N2 physisorption shows type IV isotherms with reduced pore volumes and pore sizes. 1H NMR is used to quantify functionalization degrees. Impedance spectroscopy on pressed pellets demonstrates proton conductivities up to 2 × 10−3 S cm−1 at 30 °C and 90% RH, depending on the functionalization degree, confirming sulfonic acid-mediated conduction.}}, author = {{Wagner, Tobias and Tiemann, Michael}}, issn = {{2079-4991}}, journal = {{Nanomaterials}}, number = {{3}}, publisher = {{MDPI AG}}, title = {{{Proton-Conducting Sulfonated Periodic Mesoporous Organosilica}}}, doi = {{10.3390/nano16030203}}, volume = {{16}}, year = {{2026}}, } @article{63099, abstract = {{Spray-induced gene silencing (SIGS) employing double-stranded RNA (dsRNA) offers a promising, species-specific approach for protecting crops from insect pests such as the cabbage stem flea beetle (Psylliodes chrysocephala). However, the environmental instability of dsRNA presents a major limitation to its field application. In this study, we evaluate two distinct dsRNA formulation strategies for improved stability and delivery: a bottom-up approach using chitosan-based interpolyelectrolyte complexes (IPEC) and a top-down approach employing functionalized mesoporous silica carriers (SBA-15). Both systems were comprehensively characterized in terms of size, surface potential, porosity, and release behavior. The results revealed that IPECs exhibited release kinetics that were approximately one order of magnitude faster than those of SBA-15 across all tested conditions. The two formulations significantly improved dsRNA stability against UV and heat exposure compared to free dsRNA. In feeding assays with P. chrysocephala, both carriers achieved comparable gene silencing efficacy, though dsRNA@IPEC induced more immediate effects, while dsRNA@SBA-15 displayed delayed but ultimately stronger reduction in consumed leaf area, consistent with its slower release kinetics. We demonstrate that despite structural and mechanistic differences, both delivery platforms effectively stabilized and delivered dsRNA, and offered distinct advantages depending on application needs. This work highlights how formulation strategies are key to successful SIGS and supports the development of robust, field-adaptable formulation technologies for sustainable pest management.}}, author = {{Moorlach, Benjamin W. and Epkenhans, Robert and Ju, Di and Ravidas, Banuja and Weinberger, Christian and Tiemann, Michael and Buente, Judith and Gaerner, Maik and Wortmann, Martin and Scholten, Stefan and Rostas, Michael and Keil, Waldemar and Patel, Anant V.}}, issn = {{0141-8130}}, journal = {{International Journal of Biological Macromolecules}}, publisher = {{Elsevier BV}}, title = {{{DsRNA-based carriers with pH-tuneable release kinetics for effective control of Psylliodes chrysocephala}}}, doi = {{10.1016/j.ijbiomac.2025.149697}}, volume = {{338}}, year = {{2026}}, } @article{63721, abstract = {{Defect engineering offers an effective route to tailor the local coordination environment, gas transport and excited-state processes in metal-organic frameworks (MOFs). We establish a quantitative structure-property relationship linking defect-modulated porosity...}}, author = {{Zhao, Zhenyu and Tiemann, Michael}}, issn = {{2050-7526}}, journal = {{Journal of Materials Chemistry C}}, pages = {{4743--4752}}, publisher = {{Royal Society of Chemistry (RSC)}}, title = {{{Defect Structure-Performance Correlation in Eu³⁺@UiO-66: Design of Coordination Sites for Rapid Optical O₂ Sensing}}}, doi = {{10.1039/d5tc04319k}}, volume = {{14}}, year = {{2026}}, } @article{58193, abstract = {{Zinc tin oxide (ZTO) is investigated as a photoluminescent sensor for oxygen (O2); chemisorbed oxygen quenches the luminescence intensity. At the same time, ZTO is also studied as a resistive sensor; being an n‐type semiconductor, its electrical conductance decreases by adsorption of oxygen. Both phenomena can be exploited for quantitative O2 sensing. The respective sensor responses can be described by the same modified Stern‐Volmer model that distinguishes between accessible and non‐accessible luminescence centers or charge carriers, respectively. The impact of the temperature is studied in the range from room temperature up to 150 °C.}}, author = {{Kothe, Linda and Klippstein, Josefin and Kloß, Marvin and Wengenroth, Marc and Poeplau, Michael and Ester, Stephan and Tiemann, Michael}}, issn = {{1439-4235}}, journal = {{ChemPhysChem}}, pages = {{e202400984}}, publisher = {{Wiley}}, title = {{{Oxygen‐dependent Photoluminescence and Electrical Conductance of Zinc Tin Oxide (ZTO): A Modified Stern‐Volmer Description}}}, doi = {{10.1002/cphc.202400984}}, volume = {{26}}, year = {{2025}}, } @article{59906, abstract = {{The cationic molybdenum alkylidyne N-heterocyclic carbene (NHC) complex [Mo(C-p-OMeC6H4)(OCMe(CF3)2)2 (IMes)][B(ArF4] (IMes = 1,3-dimesitylimidazol-2-ylidene) was selectively immobilized inside the pores of ordered mesoporous silica (OMS) with pore diameters of 66, 56, and 28 Å and used in the ring-expansion metathesis polymerization (REMP) of cyclic olefins to yield cyclic polymers. A strong confinement effect was observed for cis-cyclooctene (cCOE), 1,5-cyclooctadiene (COD), (+)-2,3-endo,exo-dicarbomethoxynorborn-5-ene ((+)-DCMNBE), and 2-methyl-2-phenylcycloprop-1-ene (MPCP), allowing for the synthesis of low-molecular-weight cyclic polymers even at a high monomer concentration. The exclusive formation of cyclic polymers was demonstrated by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry. Confinement also influences stereoselectivity, resulting in a pronounced increase in Z-selectivity and in an increased cis-syndiospecificity.}}, author = {{Probst, Patrick and Lindemann, Moritz and Bruckner, Johanna R. and Atwi, Boshra and Wang, Dongren and Fischer, Felix Richard and Högler, Marc and Bauer, Matthias and Hansen, Niels and Dyballa, Michael and Buchmeiser, Michael R.}}, issn = {{0002-7863}}, journal = {{Journal of the American Chemical Society}}, number = {{10}}, pages = {{8741--8750}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Ring-Expansion Metathesis Polymerization under Confinement}}}, doi = {{10.1021/jacs.4c18171}}, volume = {{147}}, year = {{2025}}, } @article{59842, author = {{Kothe, Linda and Kloß, Marvin and Wagner, Tobias and Wengenroth, Marc and Poeplau, Michael and Ester, Stephan and Tiemann, Michael}}, issn = {{1932-7447}}, journal = {{The Journal of Physical Chemistry C}}, number = {{19}}, pages = {{9239--9245}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Temperature Studies of Zinc Tin Oxide Photoluminescence for Optical O2 Sensing}}}, doi = {{10.1021/acs.jpcc.5c01678}}, volume = {{129}}, year = {{2025}}, } @article{60815, abstract = {{AbstractThe increasing demand for advanced sensing technologies drives the development of chemical sensors using innovative materials. In gas sensing, optical sensors are often used to detect gases such as CO, NOx, and O2. Oxygen sensors typically incorporate dyes into oxygen‐permeable matrices like polymers, silica, or zeolites. Alternatively, semiconductor surface chemistry can enable O2 detection. However, these approaches are often limited by slow response and recovery times and low selectivity, restricting their practical applications. The metal‐organic framework MOF‐76(Eu) and its yttrium‐modified variant, MOF‐76(Eu/Y) are reported to exhibit highly reversible and fast optical responses to varying O2 concentrations. Time‐resolved emission measurements are performed over short (seconds) and long (hours) timescales using N2 and synthetic air mixtures. Cross‐sensitivity to humidity is analyzed. Multichannel scaling photon‐counting experiments confirm quenching at the linker level, as the emission lifetime remains nearly constant. Yttrium significantly improves stability and performance at room temperature. Structural and optical changes induced by yttrium are investigated. Additionally, MIL‐78(Eu), another Eu‐BTC‐based MOF with a different coordination environment, is synthesized. Unlike MOF‐76(Eu), MIL‐78(Eu) exhibits distinct optical properties but lacks a reversible response to O2. These results highlight the potential of MOF‐76‐based materials for high‐performance O2 sensing.}}, author = {{Zhao, Zhenyu and Weinberger, Christian and Steube, Jakob and Bauer, Matthias and Brehm, Martin and Tiemann, Michael}}, issn = {{1616-301X}}, journal = {{Advanced Functional Materials}}, publisher = {{Wiley}}, title = {{{Fast‐Responding O2 Gas Sensor Based on Luminescent Europium Metal‐Organic Frameworks (MOF‐76)}}}, doi = {{10.1002/adfm.202511190}}, year = {{2025}}, } @article{60862, author = {{Grotevent, Matthias J. and Kothe, Linda and Lu, Yongli and Krajewska, Chantalle J. and Shih, Meng-Chen and Tan, Shaun and Tiemann, Michael and Bawendi, Moungi G.}}, issn = {{0897-4756}}, journal = {{Chemistry of Materials}}, number = {{15}}, pages = {{5866–5873}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Nontoxic and Rapid Chemical Bath Deposition for SnO2 Electron Transporting Layers in Perovskite Solar Cells}}}, doi = {{10.1021/acs.chemmater.5c01081}}, volume = {{37}}, year = {{2025}}, } @article{60600, abstract = {{In the search for noble metal free photocatalytic systems, iron is the dream candidate. To increase excited state lifetimes of iron complexes, the multichromophoric approach is promising, combining organic chromophores with photoactive iron complexes, potentially enabling a reservoir effect. We present a series of chromophore-functionalized complexes based on the parental FeIII complex [Fe(ImP)2][PF6] (HImP = 1,1′-(1,3-phenylene)bis(3-methyl-1-imidazole-2-ylidene)). The four organic chromophores benzene, naphthalene, anthracene, and pyrene are attached to the ImP-ligand in para-position to the coordination site to systematically investigate the influence of the steric demand and electronic properties of the chromophore on charge transfer lifetimes as well as photodynamics. A thorough ground state characterization was conducted in addition to investigations of the excited state dynamics by transient absorption spectroscopy and streak camera emission measurements. The conclusions drawn are supported by extensive DFT calculations. The emission coefficients could be significantly improved by the addition of chromophores. After excitation of the complexes with larger chromophores, coplanarization of the backbone and complex motif occurs to stabilize the formal charge. This results in population of a superligand state that exhibits a much faster radiationless relaxation to the ground state compared to the parent complex, hindering a reservoir effect.}}, author = {{Schmitz, Lennart and Argüello Cordero, Miguel A. and Al-Marri, Mohammed J. and Schoch, Roland and Egold, Hans and Neuba, Adam and Steube, Jakob and Bracht, Bastian Johannes and Bokareva, Olga S. and Lochbrunner, Stefan and Bauer, Matthias}}, issn = {{0020-1669}}, journal = {{Inorganic Chemistry}}, keywords = {{Photo}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Chromophore Induced Effects in Iron(III) Complexes}}}, doi = {{10.1021/acs.inorgchem.5c00526}}, year = {{2025}}, } @article{58180, abstract = {{A series of CoIII complexes [Co(RImP)2][PF6], with HMeImP = 1,1′-(1,3-phenylene)bis(3-methyl-1-imidazole-2-ylidene)) and R = Me, Et, iPr, nBu, is presented in this work. The influence of the strong donor ligand on the ground and excited-state photophysical properties was investigated in the context of different alkyl substituents at the imidazole nitrogen. X-ray diffraction revealed no significant alterations of the structures and all differences in the series emerge from the electronic structures. These were probed via cyclic voltammetry and UV–vis spectroscopy, detailing the influence of the different alkyl substituents on the ground-state properties. All complexes are emissive at 77 K from a 3MC state, which exhibits lifetimes in the range of 1–5 ns at room temperature, depending on the alkyl substituent. Therefore, it is clearly shown that even small differences in the electronic structure have a large impact on the details of the excited state landscape. The observed behavior was rationalized by a detailed DFT analysis, which shows that the minimum-energy crossing point to the ground-state is located only slightly above the MC energy: Consequently, nonradiative decay to the ground state at room temperature is enabled, while at 77 K this path is prohibited, leading to low-temperature 3MC emission.}}, author = {{Krishna, Athul and Fritsch, Lorena and Steube, Jakob and Argüello Cordero, Miguel A. and Schoch, Roland and Neuba, Adam and Lochbrunner, Stefan and Bauer, Matthias}}, issn = {{0020-1669}}, journal = {{Inorganic Chemistry}}, keywords = {{Photo}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Low Temperature Emissive Cyclometalated Cobalt(III) Complexes}}}, doi = {{10.1021/acs.inorgchem.4c04479}}, year = {{2025}}, } @article{61015, author = {{Baier, Dominik and Kieke, Laureen and Voth, Sven and Kloß, Marvin and Huck, Marten and Steinrück, Hans-Georg and Tiemann, Michael}}, issn = {{2379-3694}}, journal = {{ACS Sensors}}, number = {{8}}, pages = {{5664--5673}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Selective H2 Gas Sensing Using ZIF-71/In-SnO2 Bilayer Sensors: A Size-Selective Molecular Sieving Approach}}}, doi = {{10.1021/acssensors.5c00770}}, volume = {{10}}, year = {{2025}}, } @article{62819, abstract = {{Novel oxalate-bridged heterotrinuclear complexes [A][Mn2Cr(bpy)2(H2O)2Cl2(C2O4)3] (A = (CH3)2(C2H5)NH+ (1) and (CH3)(C2H5)2NH+ (2); bpy = 2,2′-bipyridine) were synthesized using an aqueous solution of [A]3[Cr(C2O4)3] as a building block in reaction with Mn2+ ions and with the addition of the N-donor ligand bipyridine. The isostructural heterometallic complex salts were characterized by single-crystal and powder X-ray diffraction, infrared and impedance spectroscopy, thermal analysis and magnetization measurements. The trinuclear anion [{Mn(bpy)(H2O)Cl(μ-C2O4)}2Cr(C2O4)]− consists of two [Mn(bpy)(H2O)Cl]+ units bridged by the [Cr(C2O4)3]3− anion, which acts as a bidentate ligand towards each of the manganese atoms. The anions are hydrogen bonded to each other via coordinated chloride anions, water molecules and oxygen oxalate atoms, resulting in two-dimensional (2D) hydrogen bonding layers. Compounds exhibit water-assisted proton conductivity behaviour, which was investigated at different temperatures and relative humidities (RH). At 25 °C, an increase in RH from 60% to 93% resulted in an obvious proton conducting switch from 9.1 × 10−11 to 5.6 × 10−5 S cm−1 for 1 and from 7.4 × 10−10 to 1.8 × 10−6 S cm−1 for 2, corresponding to high on/off ratios of about 106 for 1 and 104 for 2. In situ powder X-ray diffraction (PXRD) analysis showed that unit cell parameters of compounds 1 and 2 slightly increase when exposed to humid conditions. This confirmed that incorporation of water molecules into structures with pores and voids causes the proton conductivity switching phenomenon. Magnetic susceptibility measurements indicate a ferromagnetic interaction between Cr3+ and Mn2+ ions bridged by the bis(bidentate) oxalate group. The prepared compounds 1 and 2 were explored as single-source precursors for the formation of spinel oxide by their thermal treatment. With increasing temperature, the spinel composition changed according to the formula Mn1+xCr2–xO4 (0 ≤ x ≤ 1), where x = 0.7 at 500 °C and x = 1 at 900 °C when tet[MnII]oct[MnIIICrIII]O4 is formed. The (micro)structure, morphology, and optical properties of spinel Mn2CrO4 were characterized by PXRD, scanning electron microscopy and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activity of this oxide in degradation of the methylene blue dye under Vis irradiation without and with the support of hydrogen peroxide was further investigated.}}, author = {{Lozančić, Ana and Burazer, Sanja and Wagner, Tobias and Molčanov, Krešimir and Pajić, Damir and Androš Dubraja, Lidija and Tiemann, Michael and Jurić, Marijana}}, issn = {{2050-7526}}, journal = {{Journal of Materials Chemistry C}}, number = {{41}}, pages = {{21179--21195}}, publisher = {{Royal Society of Chemistry (RSC)}}, title = {{{Water-assisted proton conductivity and a magnetic study of heterotrinuclear oxalate-bridged compounds: molecular precursors for the Mn2CrO4 spinel}}}, doi = {{10.1039/d5tc02569a}}, volume = {{13}}, year = {{2025}}, } @article{62816, abstract = {{The increasing demand for advanced sensing technologies drives the development of chemical sensors using innovative materials. In gas sensing, optical sensors are often used to detect gases such as CO, NOx, and O2. Oxygen sensors typically incorporate dyes into oxygen-permeable matrices like polymers, silica, or zeolites. Alternatively, semiconductor surface chemistry can enable O2 detection. However, these approaches are often limited by slow response and recovery times and low selectivity, restricting their practical applications. The metal-organic framework MOF-76(Eu) and its yttrium-modified variant, MOF-76(Eu/Y) are reported to exhibit highly reversible and fast optical responses to varying O2 concentrations. Time-resolved emission measurements are performed over short (seconds) and long (hours) timescales using N2 and synthetic air mixtures. Cross-sensitivity to humidity is analyzed. Multichannel scaling photon-counting experiments confirm quenching at the linker level, as the emission lifetime remains nearly constant. Yttrium significantly improves stability and performance at room temperature. Structural and optical changes induced by yttrium are investigated. Additionally, MIL-78(Eu), another Eu-BTC-based MOF with a different coordination environment, is synthesized. Unlike MOF-76(Eu), MIL-78(Eu) exhibits distinct optical properties but lacks a reversible response to O2. These results highlight the potential of MOF-76-based materials for high-performance O2 sensing.}}, author = {{Zhao, Zhenyu and Weinberger, Christian and Steube, Jakob and Bauer, Matthias and Brehm, Martin and Tiemann, Michael}}, issn = {{1616-301X}}, journal = {{Advanced Functional Materials}}, publisher = {{Wiley}}, title = {{{Fast‐Responding O2 Gas Sensor Based on Luminescent Europium Metal‐Organic Frameworks (MOF‐76)}}}, doi = {{10.1002/adfm.202511190}}, year = {{2025}}, } @article{52372, abstract = {{Due to the hydrolytic instability of LiPF6 in carbonate-based solvents, HF is a typical impurity in Li-ion battery electrolytes. HF significantly influences the performance of Li-ion batteries, for example by impacting the formation of the solid electrolyte interphase at the anode and by affecting transition metal dissolution at the cathode. Additionally, HF complicates studying fundamental interfacial electrochemistry of Li-ion battery electrolytes, such as direct anion reduction, because it is electrocatalytically relatively unstable, resulting in LiF passivation layers. Methods to selectively remove ppm levels of HF from LiPF6-containing carbonate-based electrolytes are limited. We introduce and benchmark a simple yet efficient electrochemical in situ method to selectively remove ppm amounts of HF from LiPF6-containing carbonate-based electrolytes. The basic idea is the application of a suitable potential to a high surface-area metallic electrode upon which only HF reacts (electrocatalytically) while all other electrolyte components are unaffected under the respective conditions.}}, author = {{Ge, Xiaokun and Huck, Marten and Kuhlmann, Andreas and Tiemann, Michael and Weinberger, Christian and Xu, Xiaodan and Zhao, Zhenyu and Steinrueck, Hans-Georg}}, issn = {{0013-4651}}, journal = {{Journal of The Electrochemical Society}}, keywords = {{Materials Chemistry, Electrochemistry, Surfaces, Coatings and Films, Condensed Matter Physics, Renewable Energy, Sustainability and the Environment, Electronic, Optical and Magnetic Materials}}, pages = {{030552}}, publisher = {{The Electrochemical Society}}, title = {{{Electrochemical Removal of HF from Carbonate-based LiPF6-containing Li-ion Battery Electrolytes}}}, doi = {{10.1149/1945-7111/ad30d3}}, volume = {{171}}, year = {{2024}}, } @article{54419, abstract = {{Leaky mode resonances of the setae of Cataglyphis bombycina are found to enhance the thermal emission of the animals by near field coupling to the chitinous exoskeleton. This is remarkable, as the setae are also an adaption to enhance the reflectivity in the visible wavelength range. Both effects are dependent on morphology, dimensions and spatial arrangement. These parameters were experimentally characterized and simulated by finite difference time domain simulations to elucidate the optical impact of the setae in the mid infrared range and the contribution of leaky mode resonances. This mode of action and the setae’s optical properties in the visible range explain evolutionary strains that led to the actual morphology and size of the setae.}}, author = {{Schwind, Bertram and Wu, Xia and Tiemann, Michael and Fabritius, Helge-Otto}}, issn = {{2296-424X}}, journal = {{Frontiers in Physics}}, title = {{{Natural near field coupled leaky-mode resonant anti-reflection structures: the setae of Cataglyphis bombycina}}}, doi = {{10.3389/fphy.2024.1393279}}, volume = {{12}}, year = {{2024}}, } @inproceedings{55392, abstract = {{In dieser Arbeit werden Untersuchungen zur sauerstoffabhängigen Photolumineszenz von Zink-Zinn-Oxid-Partikeln präsentiert, welche perspektivisch für die optische Sauerstoffdetektion eingesetzt werden sollen. Zink-Zinn-Oxid zeigt eine sauerstoffabhängige Photolumineszenz im sichtbaren Spektralbereich und wird hier als eine photostabile Alternative zu den kommerziell verfügbaren metallorganischen Verbindungen vorgestellt. Der Fokus liegt dabei auf dem Einfluss der Temperatur auf die Sauerstoffsensitivität der Photolumineszenz. Wir zeigen, dass bereits leichte Temperaturerhöhungen zu einer signifikanten Verbesserung der Sauerstoffsensitivität der Photolumineszenz führen und gleichzeitig die Signalqualität erhöhen.}}, author = {{Kothe, Linda and Ester, Stephan and Poeplau, Michael and Wengenroth, Marc and Tiemann, Michael}}, booktitle = {{Proceedings 22. GMA/ITG-Fachtagung Sensoren und Messsysteme 2024}}, isbn = {{978-3-910600-01-0}}, pages = {{66 -- 71}}, title = {{{Stabilisierung von O2-sensitiven Photolumineszenzsignalen durch Temperaturvariation}}}, doi = {{10.5162/sensoren2024/A3.1}}, year = {{2024}}, } @article{56947, abstract = {{Pore engineering is commonly used to alter the properties of metal–organic frameworks. This is achieved by incorporating different linker molecules (L) into the structure, generating isoreticular frameworks. CPO-27, also named MOF-74, is a prototypical material for this approach, offering the potential to modify the size of its one-dimensional pore channels and the hydrophobicity of pore walls using various linker ligands during synthesis. Thermal activation of these materials yields accessible open metal sites (i.e., under-coordinated metal centers) at the pore walls, thus acting as strong primary binding sites for guest molecules, including water. We study the effect of the pore size and linker hydrophobicity within a series of Ni2+-based isoreticular frameworks (i.e., Ni2L, L = dhtp, dhip, dondc, bpp, bpm, tpp), analyzing their water sorption behavior and the water interactions in the confined pore space. For this purpose, we apply water vapor sorption analysis and Fourier transform infrared spectroscopy. In addition, defect degrees of all compounds are determined by thermogravimetric analysis and solution 1H nuclear magnetic resonance spectroscopy. We find that larger defect degrees affect the preferential sorption sites in Ni2dhtp, while no such indication is found for the other materials in our study. Instead, strong evidence is found for the formation of water bridges/chains between coordinating water molecules, as previously observed for hydrophobic porous carbons and mesoporous silica. This suggests similar sorption energies for additional water molecules in materials with larger pore sizes after saturation of the primary binding sites, resulting in more bulk-like water arrangements. Consequently, the sorption mechanism is driven by classical pore condensation through H-bonding anchor sites instead of sorption at discrete sites.}}, author = {{Kloß, Marvin and Schäfers, Lara and Zhao, Zhenyu and Weinberger, Christian and Egold, Hans and Tiemann, Michael}}, issn = {{2079-4991}}, journal = {{Nanomaterials}}, number = {{22}}, pages = {{1791}}, publisher = {{MDPI AG}}, title = {{{Water Sorption on Isoreticular CPO-27-Type MOFs: From Discrete Sorption Sites to Water-Bridge-Mediated Pore Condensation}}}, doi = {{10.3390/nano14221791}}, volume = {{14}}, year = {{2024}}, } @article{56080, abstract = {{CPO‐27 is a metal‐organic framework (MOF) with coordinatively unsaturated metal centers (open metal sites). It is therefore an ideal host material for small guest molecules, including water. This opens up numerous possible applications, such as proton conduction, humidity sensing, water harvesting, or adsorption‐driven heat pumps. For all of these applications, profound knowledge of the adsorption and desorption of water in the micropores is mandatory. The hydration and water structure in CPO‐27‐M (M = Zn or Cu) is investigated using water vapor sorption, Fourier transform infrared (FTIR) spectroscopy, density functional theory (DFT) calculations, and molecular dynamics simulation. In the pores of CPO‐27‐Zn, water binds as a ligand to the Zn center. Additional water molecules are stepwise incorporated at defined positions, forming a network of H‐bonds with the framework and with each other. In CPO‐27‐Cu, hydration proceeds by an entirely different mechanism. Here, water does not coordinate to the metal center, but only forms H‐bonds with the framework; pore filling occurs mostly in a single step, with the open metal site remaining unoccupied. Water in the pores forms clusters with extensive intra‐cluster H‐bonding.}}, author = {{Kloß, Marvin and Beerbaum, Michael and Baier, Dominik and Weinberger, Christian and Zysk, Frederik and Elgabarty, Hossam and Kühne, Thomas D. and Tiemann, Michael}}, issn = {{2196-7350}}, journal = {{Advanced Materials Interfaces}}, number = {{35}}, pages = {{2400476}}, publisher = {{Wiley}}, title = {{{Understanding Hydration in CPO‐27 Metal‐Organic Frameworks: Strong Impact of the Chemical Nature of the Metal (Cu, Zn)}}}, doi = {{10.1002/admi.202400476}}, volume = {{11}}, year = {{2024}}, } @article{56075, abstract = {{An isostructural series of FeII, FeIII, and Fe(IV)complexes [Fe(ImP)2]0/+/2+ utilizing the ImP 1,1′-(1,3-phenylene)-bis(3-methyl-1-imidazol-2-ylidene) ligand, combining N-heterocy-clic carbenes and cyclometalating functions, is presented. The strong donor motif stabilizes the high-valent Fe(IV) oxidation state yet keeps the FeII oxidation state accessible from the parent Fe(III)compound. Chemical oxidation of [Fe(ImP)2]+ yields stable [FeIV(ImP)2]2+. In contrast, [FeII(ImP)2]0, obtained by reduction,is highly sensitive toward oxygen. Exhaustive ground state characterization by single-crystal X-ray diffraction, 1H NMR,Mössbauer spectroscopy, temperature-dependent magnetic measurements, a combination of X-ray absorption near edge structureand valence-to-core, as well as core-to-core X-ray emission spectroscopy, complemented by detailed density functional theory (DFT) analysis, reveals that the three complexes[Fe(ImP)2]0/+/2+ can be unequivocally attributed to low-spin d6, d5, and d4 complexes. The excited state landscape of the Fe(II) and Fe(IV) complexes is characterized by short-lived 3MLCT and 3LMCT states, with lifetimes of 5.1 and 1.4 ps, respectively. In the FeII-compound, an energetically low-lying MC state leads to fast deactivation of the MLCT state. The distorted square-pyramidal state, where one carbene is dissociated, can not only relax into the ground state, but also into a singlet dissociated state. Its formation was investigated with time-dependent optical spectroscopy, while insights into its structure were gained by NMR spectroscopy.}}, author = {{Steube, Jakob and Fritsch, Lorena and Kruse, Ayla and Bokareva, Olga S. and Demeshko, Serhiy and Elgabarty, Hossam and Schoch, Roland and Alaraby, Mohammad and Egold, Hans and Bracht, Bastian Johannes and Schmitz, Lennart and Hohloch, Stephan and Kühne, Thomas D. and Meyer, Franc and Kühn, Oliver and Lochbrunner, Stefan and Bauer, Matthias}}, issn = {{0020-1669}}, journal = {{Inorganic Chemistry}}, keywords = {{Photo}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Isostructural Series of a Cyclometalated Iron Complex in Three Oxidation States}}}, doi = {{10.1021/acs.inorgchem.4c02576}}, year = {{2024}}, } @article{56074, abstract = {{Effective photoinduced charge transfer makes molecular bimetallic assemblies attractive for applications as active light‐induced proton reduction systems. Developing competitive base metal dyads is mandatory for a more sustainable future. However, the electron transfer mechanisms from the photosensitizer to the proton reduction catalyst in base metal dyads remain so far unexplored. A Fe─Co dyad that exhibits photocatalytic H2 production activity is studied using femtosecond X‐ray emission spectroscopy, complemented by ultrafast optical spectroscopy and theoretical time‐dependent DFT calculations, to understand the electronic and structural dynamics after photoexcitation and during the subsequent charge transfer process from the Fe(II) photosensitizer to the cobaloxime catalyst. This novel approach enables the simultaneous measurement of the transient X‐ray emission at the iron and cobalt K‐edges in a two‐color experiment. With this methodology, the excited state dynamics are correlated to the electron transfer processes, and evidence of the Fe→Co electron transfer as an initial step of proton reduction activity is unraveled.}}, author = {{Nowakowski, Michał and Huber‐Gedert, Marina and Elgabarty, Hossam and Kalinko, Aleksandr and Kubicki, Jacek and Kertmen, Ahmet and Lindner, Natalia and Khakhulin, Dmitry and Lima, Frederico A. and Choi, Tae‐Kyu and Biednov, Mykola and Schmitz, Lennart and Piergies, Natalia and Zalden, Peter and Kubicek, Katerina and Rodriguez‐Fernandez, Angel and Salem, Mohammad Alaraby and Canton, Sophie E. and Bressler, Christian and Kühne, Thomas D. and Gawelda, Wojciech and Bauer, Matthias}}, issn = {{2198-3844}}, journal = {{Advanced Science}}, keywords = {{Photo, Xray}}, publisher = {{Wiley}}, title = {{{Ultrafast Two‐Color X‐Ray Emission Spectroscopy Reveals Excited State Landscape in a Base Metal Dyad}}}, doi = {{10.1002/advs.202404348}}, year = {{2024}}, }