Metal-organic framework nanoparticles (nanoMOFs) are novel porous drug delivery systems whose features include high drug loading capacity, versatile functionalization, biocompatibility, and biodegradability. However, little knowledge about the nature of nanoMOFs degradation mechanism is one of many reasons that prevents their clinical use. MIL-100 (MIL stands for Matériaux de l'Institut Lavoisier) is among the most studied nanoMOF for drug delivery.Here, we investigate at the atomic scale the degradation mechanism of metal(III)-trimesate nanoMIL-100 drug carrier in biological-mimicking phosphate medium. By using solid-state NMR (ssNMR) spectroscopy, we found that the first step of nanoMIL-100(Al) degradation is the substitution of labile water ligands, resulting in new coordination bonds between Al(III) and phosphate ions, followed by the substitution of trimesate ligands leading to their release. The data indicated that the reaction-limiting step most likely is the formation of an inorganic aluminophosphate layer at the nanoparticle surface and that drug encapsulation and surface coating affect the nanoMIL-100(Al) degradation. X-ray Absorption Near Edge Structure (XANES) spectroscopy study of nanoMIL-100(Fe) degradation corroborates the hypothesized alteration mechanism of nanoMIL-100(Al). From the ensemble of data, a stepwise degradation mechanism representative for the nanoMIL-100 drug delivery system is proposed.

Molecular macrocycles are very promising electrocatalysts for the reduction of carbon dioxide into value-added chemicals. Up to now, most of these catalysts produced only C1 products. We report here that...

Iron porphyrins are attractive catalysts for the electrochemical reduction of carbon dioxide (CO2), owing to their high activity and selectivity while being tunable through ligand functionalization. Iron tetraphenyl porphyrin (FeTPP) is the simplest of them, and its catalytic behavior toward CO2 has been studied for decades. Although kinetic information is available, spectroscopic signatures are lacking to describe intermediate species along the catalytic cycle. In situ UV‐Visible and X‐ray absorption near edge spectroscopy (XANES) were used to monitor the local and electronic structure of FeTPP homogeneously dissolved in dimethyl formamide (DMF) under reductive potentials. The Fe(III) starting species was identified, together with its one, two and three electron‐reduced counterparts under both argon and CO2 atmospheres. Under argon, the second and third reductions lead to species with electronic density shared between the metal and the porphyrin backbone. In the presence of CO2 and with a low amount of protons, the doubly and triply reduced species interact with CO2 at the metallic site. In light of these results, an electronic structure for a key intermediate along the catalytic cycle of the CO2‐to‐CO reduction reaction is proposed.

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Molecular macrocycles show very promising electrocatalytic properties for the reduction of carbon dioxide. Up to now, only C1 products were produced by these catalysts. We show here that iron phthalocyanine, a commercially available molecule based on earth abundant elements, can produce light hydrocarbons upon electrocatalytic reduction of CO2 in aqueous conditions and neutral pH. When an electrochemical potential of -0.7 to -1.1 V vs. RHE is applied to a glassy carbon electrode modified with iron phthalocyanine, carbon monoxide is generated as main product. An increasing fraction of hydrogen is observed as the potential is decreased and small amounts of C1 to C4 saturated and unsaturated products are evolved. Control experiments in the absence of CO2 or catalyst does not produce any of these compounds. X-ray spectroscopic analysis of the electrode during catalysis show that the molecular catalyst remains intact and is responsible from the reaction.