In this study, we explore the interfacing of Photosystem I (PSI) with the metal-organic framework (MOF) ZIF-8 (ZIF = zeolitic imidazolate framework) through encapsulation and surface immobilization methods, aimed at stabilizing PSI through biohybrid composite formation. PSI was successfully encapsulated within ZIF-8 (PSI@ZIF-8) and immobilized on ZIF-8 surfaces (PSI/ZIF-8) using a one-pot synthesis and surface impregnation technique, respectively. Characterization techniques including powder X-ray diffraction, Fourier transform infrared spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy confirmed the formation and first-of-its-kind nanoscale visualization of the PSI/ZIF-8 composites. Spectroscopic analysis revealed that while PSI encapsulation resulted in minor structural changes potentially from scaffolding-induced stress and MOF building blocks, the overall protein integrity was maintained. Our study demonstrates that, in contrast to surface interfacing, ZIF-8 encapsulation provides a protective environment for PSI, enhancing its stability and retaining its functional properties, thereby offering an auspicious approach for the development of biohybrid materials in semi-artificial photosynthesis and other biotechnological applications.

Metal-organic frameworks (MOFs) are promising candidates for drug carrier systems due to their high porosity and tuneable structures, however, their clinical translation is restrained. Integrating MOFs into processable matrices improves mechanical properties, processability, and often drug delivery performance. Hydrogels, as soft, three-dimensional polymer networks with high flexibility and biocompatibility, are particularly favourable candidates for advanced MOF-based drug carriers. However, a lack of fundamental material studies limits full exploitation of the potential and hinders further development of such composites. To address this, this study provides a physicochemical investigation of MOF/alginate hydrogels using ZIF-8 as a benchmark MOF and thioflavin T (ThT) as a model drug. A rapid, in situ encapsulation approach enabled the fabrication of ThT@ZIF-8 (14.2 wt% loading), which was incorporated into an alginate matrix (ThT@ZIF-8@Alg) at 95 wt%, putting MOF carrier functionality in a processable form. Characterisation including X-ray diffraction, infrared and diffuse-reflectance UV/Vis spectroscopy, and electron microscopy enabled a detailed investigation of MOF properties in the composite and confirmed its retained structural integrity. Drug release studies of ThT@ZIF-8@Alg closely mirrored the pure MOF's pH-triggered behaviour. Furthermore, by comparing different methods of incorporating ThT in (ZIF-8@)Alg matrices, we demonstrate the versatility of such composites in achieving customisable release profiles. In vitro preliminary studies of the antiproliferative activity of ThT@ZIF-8@Alg in cancerous and non-tumorigenic cells support the idea of sustained controlled release of ThT over 72 h at pH 7.4. This strategy advances MOF-hydrogel-based drug delivery systems, with potential applications in topical treatments and implant coatings.

The tunability of the reaction parameter space is probed in the presented work through photoswitch-directed energy and charge transfer pathways induced by organic chromophores, hierarchically organized within a well-defined, light-harvesting metal-organic framework. Unique matrix-imposed changes in photoswitch photophysical properties, including the first report of visible light-induced photoisomerization of a spiropyran derivative, illustrate the critical synergy between the selected matrix and the photoresponsive compound. Moreover, the confined space of the utilized porous matrix allowed for mimicking isomerization kinetics of integrated sterically demanding photochromic moieties in solution. More importantly, such photoisomerization suppresses the charge transfer processes in favor of resonance energy transfer pathways instead. The demonstrated ability to shift between multiple relaxation pathways (e.g., charge transfer, energy transfer, or photoluminescence) as a function of the excitation wavelength resulted in photoswitch-directed tailoring of model phosphinylation reaction outcomes. Thus, incorporating spiropyran moieties within the framework allows for visible light to be harvested and funneled toward either a ligand-based reactive center or an acceptor molecule such as a photochromic unit. Moreover, the framework's chemical activity was promoted exclusively by organic linkers without the participation of metal nodes, the addition of (co)catalysts, or the use of harsh conditions at room temperature. Overall, this work paves the way for the development of stimulus-responsive platforms, for which chemical activity could be controlled through a photochromic moiety.

Abstract To reduce the costs of proton exchange membrane fuel cells, the amount of Pt necessary to drive efficient oxygen reduction reaction (ORR) should be minimized. Particle nanostructuring, (nano‐)alloying, and metal‐doping can yield higher activities per Pt mass through tailoring catalysts owning a high number of active sites and precise electronic properties. In this work, the atom‐precise [NBnMe3]2[Co8Pt4C2(CO)24] (Co8Pt4) cluster is encapsulated and activated in a zeolitic imidazolate framework (ZIF)‐8, which unlocks the access to defined, bare Pt−Co nanoclusters, Co8±xPt4±yNC@ZIF‐8, for the fabrication of highly active ORR catalysts. Upon controlled C‐interfacing and ZIF‐8‐digestion, Co‐doped Pt NPs (Pt27Co1) with a homogenous and narrow size distribution of (1.1±0.4) nm are produced on Vulcan® carbon. Restructuring of the Pt27Co1/C catalyst throughout the ORR measurement was monitored via high‐angle annular dark field‐scanning transmission electron microscopy and X‐ray photoelectron spectroscopy. The measured ORR mass activity of (0.42±0.07) A mgPt−1 and the specific activity of (0.67±0.06) mA cmECSA−2 compare favourably with the catalyst obtained by direct C‐interfacing the pristine Co8Pt4 cluster and with state‐of‐the‐art Pt/C reference catalysts. Our results demonstrate the potential of ZIF‐8‐mediated Pt−Co NP synthesis toward devising ORR catalysts with high Pt‐mass activity.

AbstractDie Entwicklung von multifunktionalen Materialien, die die Hell‐Dunkel‐Entkopplung der natürlichen Photosynthese nachahmen, ist eine zentrale Herausforderung im Bereich der Energieumwandlung. In diesem Artikel stellen wir MnBr‐253 vor, eine edelmetallfreie metall‐organische Gerüstverbindung (MOF), die aus Al‐Metallknotenpunkten, Bipyridin Linkern und MnBr(CO)3(Bipyridin)‐Komplexen aufgebaut ist. Bei Bestrahlung zeigen die MnBr‐253 Kolloide eine Elektronen‐Photoladekapazität von ~42 C ⋅ g−1MOF, mit kompetetiver Photoladerate (1.28 C ⋅ s−1 ⋅ g−1MOF) und einer Umwandlungseffizienz von einfallenden Photonen in Elektronen von ~9,4 % bei 450 nm. Spektroskopische und rechnerische Studien belegen eine effektive Elektronenakkumulation an dem Mn‐Komplex, während die hohe Porosität und Mn‐Beladung die bemerkenswerte Elektronenspeicherleistung erklären. Die geladenen MnBr‐253‐Pulver wurden erfolgreich für die Wasserstoffproduktion unter dunklen Bedingungen eingesetzt und damit die vom Licht entkoppelte Reaktivität der Photosynthese nachgeahmt.

An electrochemical (EC) sensor based on metalloporphyrin metal-organic framework (MOF) for the detection of parathion-methyl (PM) has been developed. The prepared MOF-525(Fe) exhibits great signal enhancement toward the electrochemical detection of PM owing to its unique structural properties and electrochemical activities. Under optimal experimental conditions, the as-prepared MOF-525(Fe) based EC sensor exhibited excellent PM sensing performance with a wide linear detection range (0.1 mu M-100 mu M) and low limit of detection (LOD, 1.4 nM). Compared to its corresponding Fe metalloporphyrin (linker), MOF-525(Fe) exhibited a superior sensitivity (28.31 mu A cm- 2 center dot mu M- 1 ), which is 3.7 times higher than the sensitivity of FeTCPP linker (7.56 mu A cm- 2 center dot mu M- 1 ) towards PM. The improved performance is associated with the high specific surface area and the large pore channels of MOF-525(Fe) facilitating a better interaction between PM and the Fe metalloporphyrin active sites, especially in the lower concentration range. Moreover, a possible affinity of the PM molecules toward Zr6 clusters may also contribute to the selective enrichment of PM on MOF-525(Fe). This EC sensor further demonstrated high selectivity in the presence of interfering molecules. The recovery results further confirm accurate PM sensing in actual samples, which suggests promising applications for the rapid detection of environmental organophosphates by metalloporphyrin MOFs.

Structural metamorphosis of metal-organic frameworks (MOFs) eliciting highly active metal-hydroxide catalysts has come to the fore lately, with much promise. However, the role of organic ligands leaching into electrolytes during alkaline hydrolysis remains unclear. Here, we elucidate the influence of organic carboxylate anions on a family of Ni or NiFe-based hydroxide type catalysts during the oxygen evolution reaction. After excluding interfering variables, i.e., electrolyte purity, Ohmic loss, and electrolyte pH, the experimental results indicate that adding organic anions to the electrolyte profoundly impacts the redox potential of the Ni species versus with only a negligible effect on the oxygen evolution activities. In-depth studies demonstrate plausible reasons behind those observations and allude to far-reaching implications in controlling electrocatalysis in MOFs, mainly where compositional modularity entails fine-tuning organic anions.

Optimizing the binding energy between the intermediate and the active site is a key factor for tuning catalytic product selectivity and activity in the electrochemical carbon dioxide reduction reaction. Copper active sites are known to reduce CO2 to hydrocarbons and oxygenates, but suffer from poor product selectivity due to the moderate binding energies of several of the reaction intermediates. Here, we report an ion exchange strategy to construct Cu-Pd paddle wheel dimers within Cu-based metal-organic frameworks (MOFs), [Cu3-xPdx(BTC)2] (BTC=benzentricarboxylate), without altering the overall MOF structural properties. Compared to the pristine Cu MOF ([Cu3(BTC)2], HKUST-1), the Cu-Pd MOF shifts CO2 electroreduction products from diverse chemical species to selective CO generation. In situ X-ray absorption fine structure analysis of the catalyst oxidation state and local geometry, combined with theoretical calculations, reveal that the incorporation of Pd within the Cu-Pd paddle wheel node structure of the MOF promotes adsorption of the key intermediate COOH* at the Cu site. This permits CO-selective catalytic mechanisms and thus advances our understanding of the interplay between structure and activity toward electrochemical CO2 reduction using molecular catalysts.

Recently, there has been growing interest in the conversion of metal-organic frameworks (MOFs) into metal-hydroxide catalysts for alkaline oxygen evolution reactions (OERs). While studies have shown that the initial OER performance of MOF-derived intermediates surpasses that of traditional metal-hydroxide catalysts, ongoing debates persist regarding these catalysts' durability and electrochemical stability. Moreover, the inevitable reorganization (aging) of MOF-derived catalysts from disordered to ordered phases, particularly those primarily composed of nickel oxyhydroxides, remains a topic of discussion. To address these issues, we propose a straightforward approach to mitigating MOF reconstruction and modulating aging in harsh alkaline environments by introducing additional organic carboxylate linkers into electrolytes. Specifically, we focus on two examples: Ni-BPDC-MOFs and NiFe-BPDC-MOFs, of formula [M-2(OH)(2)BPDC] (M: Ni and Fe; BPDC = 4,4 '-biphenyldicarboxylate). Experimental results indicate that alkaline electrolytes containing additional BPDC linkers exhibit enhanced OER activity and a prolonged electrochemical lifespan. Complemented by in situ Raman spectroscopy, our findings suggest that manipulating the coordination equilibrium of the organic linker involved in Ni-MOF formation (linker assembly) and reconstruction (linker leaching) leads to the formation of more disordered nickel oxyhydroxide phases as the active catalyst material, which shows enhanced OER performance.

Designing multifunctional materials that mimic the light-dark decoupling of natural photosynthesis is a key challenge in the field of energy conversion. Herein, we introduce MnBr-253, a precious metal-free metal-organic framework (MOF) built on Al nodes, bipyridine linkers and MnBr(CO)3(bipyridine) complexes. Upon irradiation, MnBr-253 colloids demonstrate an electron photocharging capacity of ~42 C ⋅ g-1 MOF, with state-of-the-art photocharging rate (1.28 C ⋅ s-1 ⋅ g-1 MOF) and incident photon-to-electron conversion efficiency of ~9.4 % at 450 nm. Spectroscopic and computational studies support effective electron accumulation at the Mn complex while high porosity and Mn loading account for the notable electron storage performance. The charged MnBr-253 powders were successfully applied for hydrogen evolution under dark conditions thus emulating the light-decoupled reactivity of photosynthesis.

Coordination polymers (CP) and their subgroup metal–organic frameworks (MOF) are promising classes of modular multiphoton-absorption active materials. However, a detailed knowledge of the structure–property relationship or generalized design principles remains elusive. This study examines how various packings of the chromophore linker 9,9′-stilbene-bis-carbazole-3,6-dicarboxylic acid in three synthesized zinc-based CPs affect their MPA activity. Different spatial chromophore arrangements are achieved by the so-called "pillar-layer" synthesis approach, using the chromophore and two different additional pillar linkers (4,4′-bipyridine and 1,2-bis(4-pyridyl)ethane) for CP formation. Two novel pillar-layered CPs, Zn2n(sbcd)(bpy)(DMAc)2n(H2O)3n and Zn2n(sbcd)(bpe)(DMAc)3n(H2O), are reported and examined in their two-photon-absorption-induced photoluminescence and compared to a previously synthesized CP Zn2n(sbcd)(DMAc)2n(H2O)1.5n, containing the same chromophore but no pillars. The comparison shows significant differences for the two-photon absorption cross-sections of the materials, improving it by incorporating the pillar. Our findings point toward the significance of controlling the chromophore orientation to tailor the nonlinear optical properties of the materials. These insights pave the way toward an aim-directed development of MOFs for advanced photonic applications.

Charge-transfer interactions alter the excited state properties of photosystem I after encapsulation in a metal–organic framework.

Solar-driven synthetic fuel production couples solar energy conversion and storage in the form of chemical bonds and therefore has potential as a clean technology. The past decade has witnessed the continuous development of metal-organic framework (MOF) materials with considerable interest towards combining light harvesting with catalytic CO2 conversion in one system. Built on a literature survey and data macroanalysis, this Perspective examines the development of this field by showcasing synthetic design approaches and highlighting attained milestones, while critically assessing pitfalls and opportunities. Five MOF-based material classifications for visible light-driven CO2 reduction are determined and discussed through key photocatalysis figures of merits and metrics. Analysis reveals MOFs as a favourable platform to achieve high product-selectivity CO2 photocatalysis. Non-standardized testing and reporting is found throughout this field and non-comparable product evolution rates, unverified carbon and electron source(s), and incomplete reporting checklists are identified as the main roadblocks towards accurate cross-laboratory benchmarking and breakthroughs. This Perspective additionally provides a balanced discussion and best practice recommendations to guide researchers investigating MOF-based materials for photocatalytic CO2 reduction.

Defect-containing MIL-125-(Ti)-NH2 framework, simply prepared by using pre-designed Ti-clusters, can be utilised as an efficient photocatalyst in H2 production. Its H2 evolution rate activity was revealed ∼3.5 times higher than that of corresponding defect-free framework.

Precisely designing metal nanoparticles (NPs) is thecornerstonefor maximizing their efficiency in applications like catalysis orsensor technology. Metal-organic frameworks (MOFs) with theirdefined and tunable pore systems provide a confined space to hostand stabilize small metal NPs. In this work, the MOF encapsulationof various atom-precise clusters following the bottle-around-shipapproach is investigated, providing general insights into the scaffoldingmechanism. Eleven carbonyl-stabilized Pt(M) (M = Co, Ni, Fe, and Sn)clusters are employed for the encapsulation in the zeolitic imidazolateframework (ZIF)-8. Infrared and UV/Vis spectroscopy, density functionaltheory, and ab initio molecular dynamics revealed structure-encapsulation relationship guidelines. Thereby,cluster polarization, size, and composition were found to conditionthe scaffolding behavior. Encaging of [NBnMe3](2)[Co8Pt4C2(CO)(24)] (Co8Pt4 ) is thus achieved as the firstMOF-encapsulated bimetallic carbonyl cluster, Co8Pt4 @ZIF-8, and is fully characterized includingX-ray absorption near edge and extended X-ray absorption spectroscopy.ZIF-8 confinement not only promotes property changes, like the T-dependent magnetism, but it also further allows heat-inducedligand-stripping without altering the cluster size, enabling the synthesisof naked, heterometallic, close to atom-precise clusters.

Syngas, a mixture of CO and H2 , is a high-priority intermediate for producing several commodity chemicals, e.g., ammonia, methanol, and synthetic hydrocarbon fuels. Accordingly, parallel sunlight-driven catalytic conversion of CO2 and protons to syngas is a key step toward a sustainable energy cycle. State-of-the-art catalytic systems and materials often fall short as application-oriented concurrent CO and H2 evolution requires challenging reaction conditions which can hamper stability, selectivity, and efficiency. Here a light-harvesting metal-organic framework hosting two molecular catalysts is engineered to yield colloidal, water-stable, versatile nanoreactors for photocatalytic syngas generation with highly controllable product ratios. In-depth fluorescence, X-ray, and microscopic studies paired with kinetic analysis show that the host delivers energy efficiently to active sites, conceptually yielding nanozymes. This unlocked sustained CO2 reduction and H2 evolution with benchmark turnover numbers and record incident photon conversions up to 36%, showcasing a highly active and durable all-in-one material toward application in solar energy-driven syngas generation.

Metal-organic frameworks (MOFs) have been reportedto catalyzethe oxygen evolution reaction (OER). Despite the established linksbetween the pristine MOFs and their derived metal hydroxide electrocatalysts,several limitations still preclude understanding of the critical factorsdetermining the OER performance. Of prime importance appears the choiceof MOF and how its compositions relate to the catalyst stability andin turn to the reconstruction or metamorphosis mechanisms into theactive species under OER conditions. An isoreticular series of Ni-carboxylate-typeMOFs [Ni-2(OH)(2)L] was chosen to elucidate theeffects of the carboxylate linker length expansion and modulationof the linker-linker pi-pi interactions (L= 1,4-benzodicarboxylate, 2,6-napthalenedicarboxylate, biphenyl-4,4 '-dicarboxylate,and p-terphenyl-4,4 ''-dicarboxylate). Degradationand reconstruction of MOFs were systematically investigated. The linkercontrols the transformation of Ni-MOF into distinct nickel hydroxidephases, and the conversion from alpha-Ni-(OH)(2) to beta-Ni-(OH)(2), thus correlating the Ni-MOF composition with the OER activityof the Ni-MOF-derived metastable nickel hydroxide phase mixture.

Charge Storage Long live the electron! Solar-energy conversion and long-term storage for on-demand electrical and chemical energy are crucial toward decentralized energy distribution. In article number 2207280, Julien Warnan and co-workers show how a hybrid material from a metal–organic framework and molecular rhenium complex enables light-driven accumulation of long-lived electrons. Full charge storage over several weeks is achieved as well as on-demand "dark photocatalysis" for decoupled hydrogen evolution.

Syngas, a mixture of CO and H 2 , is a high-priority intermediate for producing several commodity chemicals, e.g., ammonia, methanol, and synthetic hydrocarbon fuels. Accordingly, parallel sunlight-driven catalytic conversion of CO 2 and protons to syngas is a key step toward a sustainable energy cycle. State-of-the-art catalytic systems and materials often fall short as application-oriented concurrent CO and H 2 evolution requires challenging reaction conditions which can hamper stability, selectivity, and efficiency. Here a light-harvesting metal-organic framework hosting two molecular catalysts is engineered to yield colloidal, water-stable, versatile nanoreactors for photocatalytic syngas generation with highly controllable product ratios. In-depth fluorescence, X-ray, and microscopic studies paired with kinetic analysis show that the host delivers energy efficiently to active sites, conceptually yielding nanozymes. This unlocked sustained CO 2 reduction and H 2 evolution with benchmark turnover numbers and record incident photon conversions up to 36%, showcasing a highly active and durable all-in-one material toward application in solar energy-driven syngas generation.

Photocatalytic Nanozymes Highly active, efficient, and durable catalysts for light-driven carbon dioxide and water conversion to fuels are pivotal for a sustainable energy cycle. In article number 2207380, Philip M. Stanley, Julien Warnan, Roland A. Fischer, and co-workers demonstrate a photocatalytic nanozyme that stems from the synergy between a metal–organic framework and two molecular catalysts to deliver enzyme-reminiscent behavior toward controllable syngas evolution and artificial photosynthesis.