Publications

Isophthalic acid (IPA) has been considered to build metal-organic frameworks (MOFs), owing to its facile availability, unique connection angle-mode, and a wide range of functional groups attached. Constructing titanium-IPA frameworks that possess photoresponse properties is an alluring characteristic with respect to the challenge of synthesizing new titanium-based MOFs (Ti-MOFs). Here, we report the first Ti-IPA MOF (MIP-208) that efficiently combines the use of preformed Ti8 oxoclusters and in situ acetylation of the 5-NH2-IPA linker. The mixed solid-solution linkers strategy was successfully applied, resulting in a series of multivariate MIP-208 structures with tunable chemical environments and sizable porosity. MIP-208 shows the best result among the pure MOF catalysts for the photocatalytic methanation of carbon dioxide. To improve the photocatalytic performance, ruthenium oxide nanoparticles were photo-deposited on MIP-208, forming a highly active and selective composite catalyst, MIP-208@RuOx, which features a notable visible-light response coupled with excellent stability and recycling ability.

Mesoporous materials suffer from poor crystallinity and hydrolytic stability, lack of chemical diversity, insufficient pore accessibility, complex synthesis, and toxicity issues. Here the association of Zr-oxo clusters and isophthalate via a homometallic-multicluster-dot strategy results in a robust mesoporous metal-organic framework, denoted as MIP-206 (MIP stands for materials of the Institute of Porous Materials of Paris), that overcomes the aforementioned limitations. MIP-206, with a combination of Zr6 and Zr12 oxo-cluster inorganic building units into a single structure, exhibits meso-channels of ca. 2.6 nm and displays excellent chemical stability. Owing to the abundant variety of functionalized isophthalic acid linkers, the chemical environment of MIP-206 can be tuned without hampering pore accessibility. MIP-206 loaded with palladium nanoparticles acts as an efficient and durable catalyst for the dehydrogenation of formic acid, outperforming benchmark mesoporous materials. This paves the way toward the utilization of MIP-206 as a mesoporous platform for a wide range of potential applications.

An innovative strategy is proposed to synthesize single‐crystal nanowires (NWs) of the Al3+ dicarboxylate MIL‐69(Al) MOF by using graphene oxide nanoscrolls as structure‐directing agents. MIL‐69(Al) NWs with an average diameter of 70±20 nm and lengths up to 2 μm were found to preferentially grow along the [001] crystallographic direction. Advanced characterization methods (electron diffraction, TEM, STEM‐HAADF, SEM, XPS) and molecular modeling revealed the mechanism of formation of MIL‐69(Al) NWs involving size‐confinement and templating effects. The formation of MIL‐69(Al) seeds and the self‐scroll of GO sheets followed by the anisotropic growth of MIL‐69(Al) crystals are mediated by specific GO sheets/MOF interactions. This study delivers an unprecedented approach to control the design of 1D MOF nanostructures and superstructures.

Materials for the controlled release of nitric oxide (NO) are of interest for therapeutic applications. However, to date, many suffer from toxicity and stability issues, as well as poor performance. Herein, we propose a new NO adsorption/release mechanism through the formation of nitrites on the skeleton of a titanium‐based metal–organic framework (MOF) that we named MIP‐177, featuring a suitable set of properties for such an application: (i) high NO storage capacity (3 μmol mg−1solid), (ii) excellent biocompatibility at therapeutic relevant concentrations (no cytotoxicity at 90 μg mL−1 for wound healing) due to its high stability in biological media (<9 % degradation in 72 hours) and (iii) slow NO release in biological media (≈2 hours for 90 % release). The prospective application of MIP‐177 is demonstrated through NO‐driven control of mitochondrial respiration in cells and stimulation of cell migration, paving the way for the design of new NO delivery systems for wound healing therapy.

Microperoxidase 8 (MP8) was immobilized within MIL-101(Cr) bearing terephthalate linkers with functionalized groups (-NH2 and -SO3H). A synthesis protocol for MIL-101(Cr)-SO3H that avoids the use of toxic Cr(VI) and HF was developed. The electrostatic interactions between the MP8 molecules and the MOF matrices were found to be crucial for a successful immobilization. Raman spectroscopy revealed the dispersion of the immobilized MP8 molecules in MIL-101(Cr)-X matrices as monomers without aggregation. The presence of functional groups resulted in higher amounts of immobilized MP8 in comparison to the bare MIL-101(Cr). The catalytic activity of MP8@MIL-101(Cr)-NH2 per material mass was higher than that for MP8@MIL-101(Cr). The presence of free amino groups can thus improve the immobilization efficiency, leading to a higher amount of catalytically active species and improving the subsequent catalytic activity of the heterogeneous biocatalysts. MP8@MIL(Cr)-X also successfully catalyzed the selective oxidation of thioanisole derivatives into sulfoxides

Rational design and synthesis of metal-organic frameworks (MOFs) is of particular interest in fine-tuning the crystalline structures for given targeting applications. Considerable advance of this topic has been achieved for MOFs built with a large number of metal species but not titanium. The complex and unpredictable titanium chemistry in solution not only leads to the difficulty of isolating crystalline Ti-MOFs via direct synthesis but also results in the challenge of maintaining control over ordered structures. We demonstrated a Ti-O cluster guided green scalable preparation of a Ti-MOF (MIP-207) in a controlled manner with both post-synthetic and one-pot reaction routes. The chemical environment and functionality of the MOF structural void could be easily tuned by adopting the mixed-linker strategy, which finally resulted in an adjustable performance in CO2 capture over N2. This provides a new avenue for the rational design of Ti-MOFs in energy- and environment-related applications.

Nanomedicine recently emerged as a novel strategy to improve the performance of radiotherapy. Herein we report the first application of radioenhancers made of nanoscale metal‐organic frameworks (nanoMOFs), loaded with gemcitabine monophosphate (Gem‐MP), a radiosensitizing anticancer drug. Iron trimesate nanoMOFs possess a regular porous structure with oxocentered Fe trimers separated by around 5 Å (trimesate linkers). This porosity is favorable to diffuse the electrons emitted from nanoMOFs due to activation by γ radiation, leading to water radiolysis and generation of hydroxyl radicals which create nanoscale damages in cancer cells. Moreover, nanoMOFs act as “Trojan horses”, carrying their Gem‐MP cargo inside cancer cells to interfere with DNA repair. By displaying different mechanisms of action, both nanoMOFs and incorporated Gem‐MP contribute to improve radiation efficacy. The radiation enhancement factor of Gem‐MP loaded nanoMOFs reaches 1.8, one of the highest values ever reported. These results pave the way toward the design of engineered nanoparticles in which each component plays a role in cancer treatment by radiotherapy.

The successful development of modern gas sensing technologies requires high sensitivity and selectivity coupled to cost effectiveness, which implies the necessity to miniaturize devices while reducing the amount of sensing material. The appealing alternative of integrating nanoparticles of a porous metal–organic framework (MOF) onto capacitive sensors based on interdigitated electrode (IDE) chips is presented. We report the deposition of MIL-96(Al) MOF thin films via the Langmuir–Blodgett (LB) method on the IDE chips, which allowed the study of their gas/vapor sensing properties. First, sorption studies of several organic vapors like methanol, toluene, chloroform, etc. were conducted on bulk MOF. The sorption data revealed that MIL-96(Al) presents high affinity toward water and methanol. Later on, ordered LB monolayer films of MIL-96(Al) particles of ∼200 nm were successfully deposited onto IDE chips with homogeneous coverage of the surface in comparison to conventional thin film fabrication techniques such as drop-casting. The sensing tests showed that MOF LB films were selective for water and methanol, and short response/recovery times were achieved. Finally, chemical vapor deposition (CVD) of a porous thin film of Parylene C (thickness ∼250–300 nm) was performed on top of the MOF LB films to fabricate a thin selective layer. The sensing results showed an increase in the water selectivity and sensitivity, while those of methanol showed a huge decrease. These results prove the feasibility of the LB technique for the fabrication of ordered MOF thin films onto IDE chips using very small MOF quantities.

A series of isoreticular Zr carboxylate MOFs, MIL-140A, B and C, exhibiting 1D microporous triangular shaped channels and based on different aromatic dicarboxylate ligands (1,4-BDC, 2,6-NDC and 4,4′-BPDC, respectively), were investigated by chromatographic breakthrough experiments regarding their ability to separate hexane isomers (nC6/2MP/3MP/23DMB/22DMB). Both single and equimolar multicomponent experiments were performed at the temperatures 343, 373, and 423 K and a total hydrocarbon pressure up to 50.0 kPa using the MIL-140B form. The elution order is similar to that of the normal boiling point of the compounds nC6 > 2MP > 3MP > 23DMB > 22DMB. It is noteworthy that this material enables separation of the hexane isomers by class, linear > mono-branched > di-branched, with a selectivity (linear + mono-branched isomers/di-branched isomers) up to 10 at 343 K, decreasing, however, as the temperature increases. Grand canonical Monte Carlo simulations were further performed to gain insight into the adsorption/separation mechanisms, highlighting the crucial need to consider a tiny tilting of the organic linkers for capturing the experimental observations. The impact of the pore size was finally assessed through the comparison with MIL-140A and MIL-140C, respectively, based on multicomponent experiments at 343 K. We evidenced a significant decrease of the selectivity (about 2) in both cases while the loadings were decreased or increased for MIL-140A and MIL-140C, respectively. Additionally, MIL-140C was demonstrated to exhibit an uncommon shift in the elution order occurring between nC6 and 3MP, 3MP being the last compound to saturate in the column.

Water electrolysis is considered to be a promising way to store and convert excess renewable energies into hydrogen, which is of high value for many chemical transformation processes such as the Haber-Bosch process. The main challenge to promote the deployment of the polymer electrolyte membrane water electrolysis (PEMWE) technology lies in the design of robust catalysts for the oxygen evolution reaction (OER) under acidic conditions, since most of the transition metal-based oxides undergo structural degradation under these harsh acidic conditions. To broaden the variety of candidate materials as OER catalysts, a cation-exchange synthetic route was recently explored to reach crystalline pronated iridates with unique structural properties and stability. In this work, a new protonated phase H3.6IrO4·3.7H2O, prepared via Sr2+/H+ cation exchange at room temperature starting from the parent Ruddlesden–Popper Sr2IrO4 phase, is described. This is the first discovery of crystalline protonated iridate forming from a perovskite-like phase, adopting a layered structure with apex-linked IrO6 octahedra. Furthermore, H3.6IrO4·3.7H2O is found to possess not only an enhanced specific catalytic activity, superior to that of other perovskite-based iridates, but also a mass activity comparable to that of nanosized IrOx particles, while showing an improved catalytic stability owing to its ability to reversibly exchange protons in acid.