The convergence of population growth and climate change threatens food security on a worldwide scale. Current trends in population growth suggest that global food production is unlikely to satisfy future demand as predicted. In order to accomplish these significant objectives, the use of agrochemicals (fertilizers, pesticides, plant hormones, etc.) becomes inevitable to ensure quality and high yields. However, their intensive application has resulted in the deterioration of ecosystems. making necessary to develop more efficient and less toxic methods against pests and infections, while improving crops productivity. Importantly, large quantities of agrochemicals do not reach their intended objectives due to application practices (between 10-75% do not reach their target) and their widespread use, contributing to the deterioration of ecosystem quality, adversely affecting the health of living beings, water and soil.

Among the novel technologies considered, Metal-Organic Frameworks (MOFs) appeared as innovative and promising materials for environmental applications.[1] In this work, we take a further step and use organic agrochemicals as linkers in the preparation of MOFs, what we have called AgroMOFs. Through this original strategy, we aim to achieve a controlled agrochemical delivery and enhance crop production and quality, while reducing contamination.[2] All these studies evidenced the potential of MOFs in agriculture without damaging our environment.

Overcoming biological barriers is essential for nanomedicines to reach their intended targets, requiring the exploration of "smarter" delivery nanosystems that can discern when and where to release specific compounds, thereby avoiding off-target effects. However, translating these concepts into clinical practice demands a deeper understanding of how synthetic nanomaterials interact with the complex biological environment.

Inspired by the natural interactions of cells, viruses, and exosomes within the body, biomimetic nanocarriers replicate the structure and functionality of cellular membranes. These carriers, designed using cellular components such as those from cancer cells, platelets, and macrophages, exhibit enhanced pharmacokinetics and tissue-specific targeting capabilities (Adv. Biosys, 2020, 4 (3), 1900260; J. Nanobiotechnol. 2022, 20, 538; J .Nanobiotechnol., 2024, 22 (1), 10).). Such nanocarriers can be programmed for a variety of specialized functions, including immune evasion, homotypic targeting, and direct cytosolic delivery via membrane fusion, bypassing traditional endo-lysosomal pathways. (J. Colloid Interface Sci. 2023, 648, 488-496; J. Colloid Interface Sci, 2024). The combination of engineered biomimetic coatings with nanosized metal-organic frameworks (nanoMOFs) represents a novel approach that integrates the homotypic targeting and fusogenic capabilities of cell-derived membranes with the high payload capacity of MOFs. This innovative system demonstrates efficient cellular internalization of therapeutic agents, reduced toxicity, and enhanced cytotoxic effects in both 2D cultures and 3D spheroid models. These findings highlight the system’s potential for precise drug delivery in cancer therapy and suggest opportunities to adapt this approach for various tumor types and therapeutic agents, advancing the field of precision nanomedicine.

When cells internalized nanoparticles via endocytosis this involves also proteins bound to the surface of the nanoparticles. After internalization, the original protein corona may be partly exchanged. In case the proteins bear labels providing contrast for imaging, the in vivo distribution of the originally bound proteins as well as the one of the nanoparticles can be determined. This can be done for example with fluorescence or X-ray fluorescence based method. Colocalization analysis then provides information about the degree in which the original protein corona is retained.

Most studies about the interaction of nanoparticles (NPs) with cells are focused on how the physicochemical properties of NPs will influence their uptake by cells. However, much less is known about their potential excretion from cells. In order to control and manipulate the number of NPs in a cell however both, cellular uptake and excretion need to be studied quantitatively. Monitoring the intracellular and extracellular amount of NPs over time (after residual non-internalized NPs have been removed), enables to disentangle the influence of cell proliferation and exocytosis, which are the major pathways for the reduction of NPs per cell. Proliferation depends on the type of cells, and exocytosis depends in addition to the type of cells also on the properties of the NPs, such as their size. Examples are given on the role of these two different processes for different cells and NPs.

We present a green and high-yield method for the synthesis of core-shell nanocomposites (NCs), where magnetic nanoparticles (MNPs) are coated with UiO-66 or UiO-66-NH₂ metal-organic framework (MOF) shells, using Zr or Hf clusters. Notably, the presented method avoids the use of hazardous dimethylformamide (DMF), relying on ethanol as a solvent, making it highly suitable for biomedical applications, such as targeted drug delivery or hyperthermia. The process allows for the control of the shell thickness from 5 to tens of nm and thus to further adapt the resulting composites for the specific applications. The shell thickness is shown to directly affect the heating capabilities of the NC. The MOF shell serves as an effective insulating layer which can confine the produced heat to close vicinity of the NC. As a proof of concept and to demonstrate the versatility of our approach, we also coated Au and Pd NPs of various shapes and sizes. In summary, this work provides a facile, efficient, and reproducible methodology for the preparation of NCs with a controlled size while opening new avenues in the field of MNP@MOF nanocomposites.

The high demand of food of the ever increasing global population involves the extensive use of agrochemicals to increase crop production. However, this goal also poses real threats to human health (110,000 deaths/year and 5 million pesticide related illnesses), aquatic ecosystems, and the environment at large. One of the most common classes of pesticides, organophosphates (OPs), are highly toxic to humans and ecosystems as a consequence of their acetylcholinesterase (AChE) inhibitory activity. In this communication, I report the ability of different zinc zeolitic imidazolate frameworks (ZIFs) to behave as potential antidotes against OP poisoning. The Zn–L coordination bond (L = purine, benzimidazole, imidazole, or 2-methylimidazole) is sensitive to the G-type nerve agent model compounds diisopropylfluorophosphate (DIFP) and diisopropylchlorophosphate, leading to P–X (X = F or Cl) bond breakdown into nontoxic diisopropylphosphate. P–X hydrolysis is accompanied by ZIF structural degradation (Zn–imidazolate bond hydrolysis), with the concomitant release of the imidazolate linkers and zinc ions representing up to 95% of ZIF particle dissolution. The delivered imidazolate nucleophilic attack on the OP@AChE adduct gives rise to the recovery of AChE enzymatic activity, thereby reversing organophosphate poisoning[1,2]. 

Carboranes, polyhedral boron clusters, have emerged as a fascinating class of 3D ligands for the construction of metal-organic frameworks (MOFs) due to their unique properties, such as thermal stability, chemical inertness, and tunable electronic and steric characteristics. Carborane-based MOFs have gained significant attention in recent years as promising materials for various applications [1]. The versatility of carboranes allows for the design and synthesis of MOFs with diverse structures and properties, offering exciting opportunities for fundamental research and practical applications.

We are currently exploring the integration of lanthanide and/or transition metal ions with carborane ligands to create a range of innovative multifunctional materials. Our recent work demonstrated that the bulkiness and acidity of carborane linkers enables the synthesis of multivariate MOFs incorporating flexible combinations of multiple lanthanides. This strategy has produced Tb/Eu MOFs for anticounterfeiting [2], GdLn MOFs with magnetocaloric and luminescent properties [3], and the first-ever MOF containing eight different lanthanides [4]. Leveraging the multivariate approach, we are currently synthesizing carborane-based MOFs with strategically selected lanthanide combinations and exploring our approach to transition metals. This strategy allows us to explore the properties of "complex multifunctional materials" and develop novel materials with tailored functionalities.

When cells internalized nanoparticles via endocytosis this involves also proteins bound to the surface of the nanoparticles. After internalization, the original protein corona may be partly exchanged. In case the proteins bear labels providing contrast for imaging, the in vivo distribution of the originally bound proteins as well as the one of the nanoparticles can be determined. This can be done for example with fluorescence or X-ray fluorescence based method. Colocalization analysis then provides information about the degree in which the original protein corona is retained.

Improving the efficiency of the renewable energy conversion and storage devices is one of the main challenges in order to reduce the energy consumption and mitigate climate
change. Redox-active metal-organic (MOFs) and covalent organic frameworks (COFs) have emerged in recent years as auspicious electrode materials towards energy storage applications due to their high stability, porosity to facilitate ion diffusion, and huge chemical and structural versatility [1,2] Besides their inherent porosity, MOFs and COFs may also incorporate electronic functionalities, such as electrical conductivity, becoming attractive for their implementation as integral components in electronic devices [3]. Such porous materials present other advantages, including the easy modulation of physical properties by post-synthetic modifications, and the fine-tuning of their electronic properties is easily accomplished. In this sense, the design of mixed ionic-electronic conductors is highly desirable for energy storage applications. In the first part of the talk, I will present a proton-electron dual-conductive MOF based on tetrathiafulvalene(TTF)-phosphonate linkers and lanthanum ions. The formation of regular, partially oxidized TTF stacks with short S···S interactions facilitate electron transport via a hopping mechanism. Additionally, the material exhibits a proton conductivity of 4.9 x 10-5 S cm–1 at 95% relative humidity conditions due to the presence of free -POH groups, enabling efficient proton transport pathways [under review]. In the second part of the talk, I will present an approach to improve the electrochemical performance of an anthraquinone-based COF (DAAQ-TFP-COF) cathode material in metal anode (Li, Mg) based batteries [4]. Finally, the synthesis and electrochemical properties of a series of redox-active TTF-based COFs that were explored as high-voltage organic cathodes for lithium batteries will be discussed [5]

Zeolitic imidazolate frameworks (ZIFs) which are a subtype of metal organic frameworks (MOFs) have been extensively used to prepare catalyst materials for a variety of electrochemical reactions for energy conversion and storage applications. Most notable examples of ZIFs used for that purpose include ZIF-8 and ZIF-67 etc. Particularly ZIF-8 with its high surface area, defined pore structure and tunable particle size is widely utilized as a platform material to prepare so-called metal- and nitrogen-doped carbon (M-N-C) catalysts with M= Co, Fe, Ni, Zn etc., which are an emerging class of catalyst materials [1], [2]. The active sites in M-N-Cs ideally have M-N₄ coordination resembling to metal centres in macromolecules such as porphyrins and phthalocyanines [3]. Most representative examples of M-N-Cs include Fe-N-Cs, Co-N-Cs and Ni-N-Cs etc. which are showing promising activities for a variety of electrochemical reactions e.g. oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO₂RR) and hydrogen evolution reaction (HER). The structures of M-N-C catalysts are quite complex and require a fine balance between morphological, electronic, and chemical properties to reach optimal electrocatalytic activities. In this talk, I will present our activities on (i) the preparation of phase-pure M-N-C catalysts derived from ZIF-8 via active-site imprinting [4],[5] and highlight the benefits of our strategy to achieve high density of active sites and enhanced electrochemical performance levels [6] and (ii) feasibility of using gas physisorption techniques as a new approach to quantify active sites in M-N-Cs. The challenges of maximizing active site utilization and eliminating unfavourable mass-transport characteristics faced by ZIF-8 derived M-N-Cs in electrochemical energy devices e.g. fuel cells will also be briefly discussed.

Metal-organic frameworks (MOFs) have been one of the most advancing classes of materials in the past few years, with immense potential in the fields of catalysis,[1] gas storage,[2] drug delivery,[3] water purification,[4] etc. However, the fundamental aspect of determining the precise chemical composition of the synthesised MOFs is lacking sufficient attention, although it is crucial for many advanced applications, such as catalysis.

Here, we developed a simple yet robust methodology to derive the minimal formula of the synthesised MOF material.[5] To achieve this, we combine Nuclear Magnetic Resonance (NMR) spectroscopy, Thermogravimetric analysis (TGA), and UV-Vis spectroscopy. We investigated the previously used methodologies that solely rely on TGA and demonstrated why the assumptions that were made in this technique are not justified. We further dive deep into the use of NMR to quantify the different organic molecules present in the framework. We have also shown the crucial influence of digestion methods and relaxation time on the accurate determination of the minimal formula. Finally, we highlighted the importance of determining the amount of chloride ions in the MOF structure and showcased that chloride is present in significant quantities when a MOF is synthesized from chloride-based precursors such as ZrCl₄ of ZrOCl₂.

We also introduce the concept of “room temperature molar mass” as this is more significant in terms of applications of MOFs and has arrived at a fully charge-balanced and chemically feasible minimal formula. We used our methodology to derive the room temperature minimal formula of MOF-808 and UiO-66 to show the generality of our technique. This work thus lays the foundation for a more rigorous reporting of MOF compositions.

The application of Metal-organic frameworks (MOFs), especially nanoscale MOFs, in biomedicine has become a rapidly developing hot research topic in the last years. This interest arises from their unique properties, mainly their high chemical and structural diversity, tunability, and potential multifunctionality. Since the structure of the MOF will directly influence its properties, function, and biological performance, each MOF must be designed specifically for each target application. In this direction, the engineering of MOFs involves the incorporation of functional units to endow them with new properties and functions, with the ultimate aim of developing novel MOF-based nanoplatforms with improved performances for some specific applications. There is a wide variety of interesting functional units that can be smartly combined with MOFs, ranging from metallic nanoparticles, to polymers, fluorinated agents or therapeutic biomolecules, and the appropriate synthetic and/or functionalization strategy must be optimized depending on the nature and characteristics of the functional unit and the type of MOFs. To illustrate the potential and bright future of MOFs in the field of biomedicine, this talk will show an overview of different possibilities through a series of concrete examples focused on different application areas, including MOF-nanoplatforms for the generation of drugs inside cells, phototherapy, renal therapy or hemodialysis, and immune-mediated therapies.
 

Metal-Organic Frameworks (MOFs) are crystalline, porous materials composed of metal or metal clusters bonded by polytopic organic ligands.¹ These materials possess unique physicochemical properties, making them attractive for various applications such as gas storage/separation, catalysis, drug delivery, chemical sensing, and water treatment.² On the other hand, plasmonic nanoparticles exhibit unique optical properties, including Localized Surface Plasmon Resonance (LSPR), which make them suitable for applications such as catalysis, sensing, and heating.^3,4

Combining these two distinct materials presents challenges due to the functionalization of the nanoparticle core, which must fulfill two roles: adapting the nanoparticles to the high-temperature and high-pressure conditions typically required for MOF synthesis, and promoting the controlled growth of MOFs onto the cores.

However, there are limited reports in the literature regarding the growth of Zr-based MOFs, such as the UiO family, on plasmonic nanoparticles. This is primarily due to the propensity of high temperatures and long reaction times to cause reshaping or complete dissolution of the nanoparticles, resulting in either etching or undesirable changes in optical properties.

In this study, we developed synthetic methodologies aimed at preventing reshaping and etching during the synthesis of nanocomposites comprising Zr-based MOFs and Au nanoparticles functionalized with polyethylene glycol. These nanocomposites exhibit absorption around 800 nm and maintain their infrared absorption properties even at lower synthesis temperatures, thereby increasing reaction yields. Additionally, the nanocomposites demonstrate colloidal stability and have been extensively characterized.

Our findings not only provide insights into overcoming challenges associated with MOF-plasmonic nanoparticle composites but also offer a foundation for the development of stable and functional nanomaterials suitable for a wide range of applications.⁵

Group IV metal-organic frameworks (MOFs) with phosphonate linkers offer enhanced stability and potential applicability compared to their carboxylate-based counterparts. However, synthetic strategies for accessing such frameworks remain underdeveloped. The inorganic nodes of MOFs - group IV metal oxo clusters, are considered the smallest conceivable nanocrystal prototypes. Their structurally similar inorganic core, capped with an organic ligand shell, allows them to be treated as model systems for colloidally stable nanocrystals of the same composition.[2]

The effectiveness of nanocrystals in many applications depends on their surface chemistry. Here, we leverage the atomically precise nature of zirconium and hafnium oxo clusters to gain fundamental insights into the thermodynamics of ligand binding. Using a combination of theoretical calculations and experimental spectroscopic techniques, we investigate the interactions between the M₆O₈⁸⁺ (M = Zr, Hf) cluster surface and various ligands: carboxylates, phosphonates, dialkylphosphinates, and monosubstituted phosphinates. We refute the common assumption that the adsorption energy of an adsorbate is unaffected by the surrounding adsorbates. Through ligand exchange from the carboxylate-capped clusters, we find that dialkylphosphinic acids possess too much sterical hindrance, preventing complete exchange. Monoalkyl or monoaryl phosphinic acids drive off carboxylates quantitatively and we obtained the crystal structure of M₆O₄(OH)₄(O₂P(H)Ph)₁₂ (M = Zr, Hf), first fully phosphinate-capped clusters. Phosphonic acids, however, cause a structural reorganization into amorphous metal phosphonate as indicated by Pair Distribution Function analysis.

These findings rationalize the absence of phosphonate-capped M₆O₈ clusters and underscore the challenges in preparing group IV phosphonate MOFs. Our results further reinforce the notion that monoalkylphosphinates, as carboxylate analogs with superior binding affinities, are promising alternative linkers for MOFs. We infer that while metal oxo clusters serve as minimalistic prototypes for oxide nanocrystals, their surface chemistries exhibit significant diversity due to variations in surface curvature. The development of a versatile toolkit for precise manipulation of cluster surfaces could unlock new opportunities in designing advanced cluster-based materials.

In recent years, metal−organic frameworks (MOFs) have been extensively investigated for diverse heterogeneous catalysis due to their diversity of structures and outstanding physical and chemical properties.^[1] Currently, most related work focuses on employing MOFs as porous substrate materials to fabricate confined nanoparticle or heteroatom doped electrocatalysts.^[2] However, they must typically be annealed at high temperature before application.

Herein, a simple room-temperature process is used to synthesize a series of bi-, tri-, tetra- or penta-metallic MOFs directly on a nickel or steel substrate. The as-prepared MOFs are applied directly as highly efficient oxygen evolution reaction (OER) electrocatalysts with no post-annealing treatment. Highest OER activity was found for the tetra-metallic Ni₂Co₂MnZnFe_x-BTC MOF outperforming those of single metal MOFs and commercial precious RuO₂ catalysts significantly. With this MOF as the catalyst, OER current densities of 10 and 100 mA cm^-2 can be achieved with overpotentials of only 222 and 250 mV, respectively. Meanwhile, a small Tafel slope of 30 mV dec^-1 was obtained.

It was found important that some iron ions from the steel substrate are incorporated in the MOF structure due to local partial corrosion; if a nickel substrate is used some few iron ions must be added to obtain electrocatalytic activity. The presence of BTC linkers is important as well; without them no active material is deposited on the substrates.

Moreover, the catalysts show high electrochemical stability in strong basic solution as used in alkaline electrolysis. This work demonstrates that bi- and multi-metallic MOFs prepared by easy and energy-efficient deposition procedures are promising as advanced catalysts for electrochemical energy conversion.

In addition to their high surface area, variability in pore size and connectivity, and compositional versatility, the ability to be modified by post-synthetic strategies has helped to tailor the properties of many families of Metal-Organic Frameworks (MOFs) to specific applications by using relatively simple methods. In this contribution, we will discuss how the use of heterobimetallic titanium clusters can enable alternative post-synthetic strategies suitable for directing structural transformations into new ultraporous architectures amenable to isoreticular design, or for integrating additional components with long-range periodicity into a pre-assembled MOF.

In 2018 we introduced a bimetallic titanium SBU, [Ti₂Ca₂(O)₂(RCO₂)₈(H₂O)₄] (Ti₂Ca₂), that combines hard (Ti⁺⁴) and soft metal sites (Ca²⁺).^[1] In addition to being compatible with the systematic design of frameworks for controllable pore dimensions and topologies,^[2] the dynamic nature of the Ca-O bonds allows integrating compositional and structural changes in the crystal whilst maintaining a periodic structure thanks to the robustness imposed by the Ti⁺⁴ nodes. This allows the preparation of crystals of MUV101 and MUV-102, heterometallic titanium MOFs isostructural to archetypical frameworks as MIL-100 and HKUST, by reaction of MUV-10(Ca) with transition metals.^[3] This metal-induced topological transformation provides control over the formation of hierarchical micro-/mesopore structures at different reaction times and enables the formation of heterometallic titanium MOFs that are inaccessible under solvothermal conditions at high temperature, thus opening the door for the isolation of additional titanium heterometallic phases not linked exclusively bound to trimesate linkers.^[4] We will also illustrate how this combination of hard and soft coordination bonds can facilitate the translocation and ordered positioning of small molecules in these porous architectures.^[5] This is triggered by an adaptive response of the solid through a cooperative interplay between the conformational changes of the guest molecule and the reversible reconfiguration of the pore windows through the breaking/formation of coordination bonds with the Ca²⁺ sites in the framework.