Laurent Jouffret

Fluorination has emerged as a powerful strategy for tailoring the structure, chemistry, and electronic properties of two-dimensional (2D) materials beyond conventional surface functionalization. This review highlights fluorination chemistry as a versatile toolbox for the controlled design of layered materials, with particular emphasis on synthesis approaches, reaction mechanisms, and structural transformations of graphene and carbon materials, hexagonal boron nitride (h-BN), transition-metal dichalcogenides (TMDs), MXenes, layered double hydroxides (LDHs), and layered metal oxides. Various fluorination methods, including direct fluorination using F₂, XeF₂ treatment, HF-based processes, plasma-assisted fluorination, electrochemical routes, hydrothermal/solvothermal methods, and polymer-mediated topochemical fluorination, are critically discussed regarding their mechanisms, advantages, limitations, and ability to control fluorine content, bonding configuration, defect formation, and phase evolution. Finally, current challenges related to fluorine control, scalability, environmental impact, and advanced characterization are discussed. Fluorination–defluorination chemistry is thus presented as a promising platform for atomic-scale engineering of 2D materials.

To investigate the influence of particle size and morphology on the high-pressure (HP) behaviour of fluoroperovskites, NaNiF3 samples exhibiting distinct microstructural characteristics were synthesised using precipitation-dehydration, solvothermal, and hydrothermal routes. Ambient-condition characterisation confirmed significant differences in particle crystallinity, size, morphology, and specific surface area between the samples. Their high-pressure structural evolution was investigated up to 17 GPa at room temperature using synchrotron X-ray diffraction (SXRD) in a diamond anvil cell (DAC) with sodium chloride (NaCl) as the pressure-transmitting medium (PTM). Although no perovskite-to-post-perovskite (Pv-pPv) transition was observed within the investigated pressure range, the samples exhibited distinct compression response, highlighting the influence of particle size and morphology on their response to pressure. This trend was further confirmed by multi-anvil (MA) experiments. While the nanosized samples remained in the Pv structure after treatment at 12.5 GPa and 500 °C, the microparticulate sample underwent a partial Pv-pPv transition under comparable pressure–temperature–time (P–T–t) conditions. These results indicate that microstructural parameters influence the transformation pathway and kinetics of ternary fluorides such as NaNiF3, with microparticulate materials transforming more readily than their nanosized counterparts.

The reaction between decavanadate clusters and organic cations has attracted intensive research interest due to the interesting properties of the resulting materials. The asymmetric unit of their structure consists of a complete dihydrogen decavanadate anion ([H₂V₁₀O₂₈]⁻⁴), four organic 1-vinyl-1H-imidazol-3-ium cations (4[C₅H₇N₂]⁺¹), and four water molecules. The stability of the crystal arises from O–H⋯O, N–H⋯O and C–H⋯O bonding, with structural stabilization largely attributed to water molecules. Crystals have been grown by slow evaporation of the solution at room temperature. The compound has been chemically and spectroscopically characterized by a combination of elemental and thermal analyses, together with IR spectroscopy, and its structure was elucidated by X-ray diffraction. Density functional theory calculations combined with Hirshfeld surface, QTAIM, NCI, NBO, and frontier molecular orbital analyses reveal that the electronic structure of the hybrid system is governed by organic-to-inorganic charge transfer, with the organic moiety acting as an electron donor and the polyoxodecavanadate cluster serving as an electron acceptor. The combined experimental and theoretical results provide a coherent description of the bonding, noncovalent interactions, and electronic properties of the title compound.

La chimie du solide des composes hybrides organiques inorganiques contenant l’uranium a été récemment enrichie par une multiplication de publications concernant des matériaux bi ou tri dimensionnels. Ce travail porte sur la synthèse hydrothermale de composés des systèmes uranyle-vanadate-amines et uranyle-phosphate-amines. La résolution des structures de ces composés s’est faite par diffraction des rayons X sur monocristal. Leur stabilité thermique a aussi été étudiée. Suivant le pH de la solution, et l’amine utilisée, différentes familles de composés apparaissent. A pH basique, les composés obtenus sont bidimensionnels avec des couches correspondant à celles des phases naturelles, à savoir couches de type carnotite pour les uranyle-vanadates ou de type autunite pour les uranyle-phosphates. A pH acide, des composés à charpente tridimensionnelle sont stabilisés par la présence des amines. Les arrangements résultent de couches uranyle-vanadate ou uranyle-phosphate de type uranophane reliées par des piliers uranyle. Ces arrangements présentent différents rapports U/V ou U/P selon l’isomérie géométrique de la couche uranophane. L’identification de nouveaux isomères géométriques a généré une classification de ces isomères qui permet une comparaison simple et la compréhension de leur formation. Enfin, l’utilisation de l’éthylène diamine dans le système uranyle-phosphate permet la réduction in situ de l’uranium (VI) en uranium (IV) et la formation d’un phosphate d’uranium (IV) où les couches uranium-phosphate alternent avec des couches d’éthylène diamine diprotonnée

Nitrosylium hexafluorouranate NOUF₆ has been discovered in the late 1950s. It is part of the "NOUF" family currently represented by five members: NOUF₆, NOUF₇, (NO)₂UF₈, NO₂UF₆ and NO₂UF₇. Only two could be subject to careful characterization due to their high reactivity with the atmosphere and the nature of the fluorinating agents used: nitrosyl fluoride FNO and nitryl fluoride FNO₂, which are not commercial. This article proposes to revisit the synthesis of the least described compounds in the literature (NOUF₇, NO₂UF₆ and NO₂UF₇) thanks to a setup capable of both allowing the synthesis of nitrogen oxyfluorides and reacting them with uranium hexafluoride (UF₆). The reactions can be followed by gas-phase infrared spectroscopy, and the solid products will be characterized by powder X-ray diffraction and Raman spectroscopy.