Julien Warnan

Efficient harvesting, storage, and on‐demand release of solar energy are essential for overcoming the intermittency of sunlight and enabling continuous solar energy‐driven processes, yet achieving storage of photogenerated charge remains challenging. Here, we report a Ti‐based bipyridine MOF, COK47‐bpy, and its ReCl(CO) ₃ ‐functionalized analogue, ReCl47‐bpy , as photochargeable materials for time‐decoupled solar energy utilization. Re incorporation introduces localized photosensitizing and “electron sink” sites while preserving the parent framework structure, enabling visible‐light response, faster charge accumulation, and improved charge retention. In colloidal suspension, ReCl47‐bpy reaches an electron storage capacity of 19.5 C g ⁻¹ _MOF under simulated solar irradiation and retains about 70% of the stored charge after 2.5 months. The stored electrons can be released on demand for dark hydrogen (H ₂ ) evolution with electron‐to‐H ₂ efficiencies exceeding 90%. Beyond colloids, when fabricated as robust FTO‐supported layers, ReCl47‐bpy |FTO photoelectrodes deliver capacities of up to ∼7.0 mAh g ⁻¹ _MOF upon photocharging under 1 Sun irradiation. Overall, this work establishes Re‐functionalized Ti‐MOFs as versatile platforms for solar‐driven charge storage, dark photocatalysis, and MOF‐based photoelectrodes, toward the development of next‐generation MOF‐based energy devices.

This work gives insight into rapid, in situ drug encapsulation in ZIF-8, its incorporation into an alginate matrix at 95 wt%, yielding MOF composites with controlled drug release, and preliminary in vitro studies on their antiproliferative activity.

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.

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.

Bio-nanohybrid devices featuring natural photocatalysts bound to a nanostructure hold great promise in the search for sustainable energy conversion. One of the major challenges of integrating biological systems is protecting them against harsh environmental conditions while retaining, or ideally enhancing, their photophysical properties. In this mainly computational work we investigate an assembly of cyanobacterial photosystem I (PS I) embedded in a metal-organic framework (MOF), namely the zeolitic imidazolate framework ZIF-8. This complex has been reported experimentally [Bennett et al., Nanoscale Adv., 2019, 1, 94.] but so far the molecular interactions between PS I and the MOF remained elusive. We show via absorption spectroscopy that PS I remains intact throughout the encapsulation-release cycle. Molecular dynamics (MD) simulations further confirm that the encapsulation has no noticeable structural impact on the photosystem. However, the MOF building blocks frequently coordinate to the Mg²⁺ ions of chlorophylls in the periphery of the antenna complex. High-level quantum mechanical calculations reveal charge-transfer interactions, which affect the excitonic network and thereby may reversibly change the fluorescence properties of PS I. Nevertheless, our results highlight the stability of PS I in the MOF, as the reaction center remains unimpeded by the heterogeneous environment, paving the way for applications in the foreseeable future.

Die 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⁻¹_MOF, mit kompetetiver Photoladerate (1.28 C ⋅ s⁻¹ ⋅ g⁻¹_MOF) 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.

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.

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.