Michaël Carboni

Recovery of metals from simulant spent lithium-ion battery as organophosphonate coordination polymers in aqueous media

An innovative approach is proposed for the recycling of metals from a simulant lithium-ion battery (LIBs) waste aqueous solution. Phosphonate organic linkers are introduced as precipitating agents to selectively react with the metals to form coordination polymers from an aqueous solution containing Ni, Mn and Co in a hydrothermal process. The supernatant is analyzed by ICP-AES to quantify the efficiency and the selectivity of the precipitation and the materials are characterized by Scanning Electron Microscopy (SEM), Powder X-Ray Diffraction (PXRD), Thermogravimetric Analyses (TGA) and nitrogen gas sorption (BET). Conditions have been achieved to selectively precipitate Manganese or Manganese/Cobalt from this solution with a high efficiency. This work describes a novel method to obtain potentially valuable coordination polymers from a waste metal solution that can be generalized on any waste solution.

Phosphoester Hydrolysis: The Incoming Substrate Turns the Bridging Hydroxido Nucleophile into a Terminal One

Identifying the active nucleophile in hydrolysis reactions catalyzed by binuclear hydrolases is a recurrent problem and a matter of intense debate. We report on the phosphate ester hydrolysis by a Fe(III)Fe(II) complex of a binucleating ligand. This complex presents activities in the range of those observed for similar biomimetic compounds in the literature. The specific electronic properties of the Fe(III)Fe(II) complex allowed us to use (1)H NMR and Mössbauer spectroscopies to investigate the nature of the various species present in the solution in the pH range of 5-10. Both techniques showed that the hydrolysis activity is associated to a μ-hydroxido Fe(III)Fe(II) species. Further (1)H NMR experiments show that binding of anions or the substrate changes this bonding mode suggesting that a terminal hydroxide is the likely nucleophile in these hydrolysis reactions. This view is further supported by the structure determination of the hydrolysis product.

Sorption and photodegradation under visible light irradiation of an organic pollutant by a heterogeneous UiO-67–Ru–Ti MOF obtained by post-synthetic exchange

The synthesis of a UiO-67 based MOF was made through the combination of two synthetic pathways, first a solvothermal synthesis in the presence of two different linkers, one for the structure and one to work as a light antenna (based on Ru), followed by a process of post-synthetic metal exchange on the coordination node to include a catalyst (Ti). This MOF has been able to remove an organic pollutant from an aqueous solution and to catalyze the degradation of the pollutant under visible light irradiation.

Cis/Trans Isomerizations in Diiron Complexes Involving Aniline or Anilide Ligands

We have recently reported a deprotonation-induced valence inversion within a phenoxido-bridged mixed-valent diiron(II,III) complex. The initial aniline coordinated to the Fe(II) site reacts with triethylamine, and the resulting complex contains an anilide ligand coordinated to the Fe(III) ion. The behavior of these complexes in acetonitrile is indeed more intricate. Owing to the very distinctive spectroscopic signatures of the complexes, the conjunction of NMR, Mössbauer, and UV-visible absorption spectroscopies allows one to evidence two isomerization reactions, one involving the aniline linked to Fe(II) and the other the anilide on Fe(III). Theoretical calculations sustain this conclusion. Aniline in the cis position versus the bridging phenoxide is shown to be the most stable isomer while the anilide trans to the phenoxido bridge is favored. The trans isomer of the aniline complex is more acidic than the cis one by 1 pKa unit. Isomerization of the anilide complex is 10 times faster than the analogous isomerization of the aniline complex. Both reactions are proposed to proceed through a unique mechanism. This is the first time that such isomerization reactions are evidenced in dinuclear complexes.

Deprotonation in Mixed-Valent Diiron(II,III) Complexes with Aniline or Benzimidazole Ligands

We have previously investigated cis/trans isomerization processes in phenoxido-bridged mixed-valent Fe(II)Fe(III) complexes that contain either one aniline or one anilide ligand. In this work, we compare the properties of similar complexes bearing one terminal protic ligand, either aniline or 1H-benzimidazole. Whatever the ligand, (1)H NMR spectroscopy clearly evidences that the complexes are present in CH3CN as a mixture of cis- and trans-isomers in a close to 1:1 ratio. We show here that addition of NEt3 indeed allows the deprotonation of these ligands, the resulting complexes bearing either anilide or benzimidazolide that are coordinated to the ferric site. The latter are singular examples of a high-spin ferric ion coordinated to a benzimidazolide ligand. Whereas the trans-isomer of the anilide complex is the overwhelming species, benzimidazolide species are mixtures of cis- and trans-isomers in equal proportions. Moreover, cyclic voltammametry studies show that Fe(III)Fe(III) complexes with 1H-benzimidazole are more stable than their aniline counterparts, whereas the reverse is observed for the deprotonated species.

Recent status on MOF thin films on transparent conductive oxides substrates (ITO or FTO)

The interest in metal–organic frameworks (MOFs) is growing exponentially due to their remarkable properties (high porosity, large surface area, thermal, and mechanical stability). They are usually synthesized as bulk crystalline solid materials. However, the sustainable development of MOFs as technological systems, material design and tuning their shape are of prime importance in order to use them as efficient devices. The development of deposition or the growing approaches of these materials on various supports provide useful techniques to reach this goal. Moreover, to study some particular properties, such as optical, catalysis, or even photocatalysis, MOFs need to be attached onto transparent conductive oxide (TCO) supports, such as indium tin oxide (ITO) or fluorine-doped tin oxide (FTO). This review is focused on the early advances in the growth and deposition of MOFs on TCO supports via various conventional methods.

BTEX removal from aqueous solution with hydrophobic Zr metal organic frameworks

The Zr based metal organic framework, UiO-66, has been synthesized along with its isostructural equivalence tetrafluorinated, the UiO-66-F4. The corresponding ligands to these MOFs are the widely used BDC (1,4-benzenedicarboxylic acid) and the TFBDC (2,3,5,6-Tetrafluoro-1,4-benzenedicarboxylic acid). These coordination materials have been tested towards the sorption of the organic pollutants (Benzene, Toluene, Ethylbenzene and Xylene) in aqueous phase and both materials showed capacities to adsorb all the pollutants. It has been possible to compare the efficiency in the adsorption of two iso-structural MOFs, which will behave differently due to the hydrophobic behavior of the UiO-66-F4 MOF. The addition of F in the structure of the ligand of the MOF allows to obtain a hydrophobic material by changing the nature of the interactions between the adsorbent and the adsorbate from π-π stacking in the pristine UiO-66 to hydrophobic interactions in the UiO-66-F4. However, size of the pores has also revealed an important effect, since steric impediments will decrease the capacity of the fluorinated MOF towards the sorption of bigger molecules.

Metal–organic framework sorbents for the removal of perfluorinated compounds in an aqueous environment

Special attention is paid to synthetic anionic surfactants, particularly the perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) anions (denoted as PFOX), due to their persistence in aquatic environments and the high toxicity of these surfactants. Two metal organic frameworks (MOFs) based on Zr-oxo clusters, UiO-66 and the equivalent perfluorinated UiO-66-(F4), were prepared and tuned for the selective adsorption of PFOA and PFOS from an aqueous solution. The MOFs have been characterized by powder X-ray diffraction, thermogravimetric analysis, infra-red spectroscopy, and BET measurement and their efficiency for the uptake of PFOX has been determined. The influence of several parameters such as the kinetics, the m/V ratio or the temperature on the adsorption capacity was investigated. These two porous MOFs have been revealed to be excellent materials for the removal of these pollutants with saturation sorption capacities of around 470 mg g−1 under some conditions. The fluorinated MOF cavity of UiO-66-(F4) has been revealed to increase the affinity for the sorption of fluorinated pollutants due to the fluorine–fluorine interactions without changing drastically the saturation capacity compared to UiO-66. These results indicate that Zr-MOFs provide a promising platform for the removal of fluorinated organic pollutants from aqueous solutions.