Liquid crystal properties resulting from synergetic effects between non-mesogenic organic molecules and a one nanometre sized octahedral transition metal cluster.

International audienceThis work presents the synthesis and studies of a red-NIR luminescent liquid crystal compound based on an octahedral metallic cluster core orthogonally bounded to six non-mesogenic organic ligands. It evidences synergetic effects between the organic and inorganic parts of the hybrid, resulting in the generation of liquid crystal properties on cooling from the isotropic melt

From metallic cluster-based ceramics to nematic hybrid liquid crystals: a double supramolecular approach.

International audienceWe describe a new supramolecular approach combining host-guest and electrostatic interactions to design hybrid materials containing polyanionic bulky inorganic compounds and showing liquid crystalline properties

Enhancement of smectic C mesophase stability by using branched alkyl chains in the auxiliary ligands of luminescent Pt(II) and Pd(II) complexes.

International audienceA novel series of Pd(II) and Pt(II) complexes based on cyclometallated imine ligands and N-benzoylthiourea (BTU) derivatives as auxiliary ligands has been prepared and their liquid crystalline properties as well as photophysical properties have been investigated. The crystal structure of one cyclometallated Pt(II) complex with N-(p-F-phenyl)-N'-benzoylthiourea as a co-ligand has been solved. The liquid crystalline properties have been investigated by a combination of DSC, POM and variable temperature powder X-ray diffraction. These new metallomesogens display either a monotropic SmC phase or both SmA and SmC phases, depending on the number of alkoxy groups attached to the imine ligand, alkyl chain length or the use of branched alkoxy terminal groups. We found that the introduction of branched alkoxy terminal groups lead to lower transition temperatures and stabilization of the SmC phase in both the Pd(II) and Pt(II) complexes. While the Pd(II) complexes display no emission, the Pt(II) complexes show good emission properties in solution, in the solid state and as a PMMA film at room temperature, and their investigation is reported

Deep red luminescent hybrid copolymer materials with high transition metal cluster content

Accepted 04 Dec 2013International audienceThe hybrid strategy is a powerful approach to design functional materials by combining inorganic dyes with an organic matrix. However, introducing high contents of inorganic species within the hybrid material is a real challenge that requires a perfect balance between the interactions of both components to avoid mainly phase segregation problems. Based on our demonstration on an anionic molybdenum cluster, we present a general method to introduce high contents of such class of nanometre sized inorganic molecular deep red dyes in a polymer matrix. Our strategy exploits the physical interactions between the organic and inorganic parts of the hybrid material and allows a high cluster rate to be introduced (up to 50 wt%) in the polymer matrix. The resulting hybrids are remarkably stable even after several months of ageing. Moreover, the Mo clusters maintain their intrinsic deep red luminescence properties while the polymer organic matrix fully maintains its processability, thanks to the di-anionic character of the Mo6 clusters. Such materials show promising prospects in applications needing deep red emitters

Advances in the Engineering of Near Infrared Emitting Liquid Crystals and Copolymers, Extended Porous Frameworks, Theranostic Tools and Molecular Junctions Using Tailored Re6 Cluster Building Blocks

International audienceAt the occasion of the fiftieth birthday of the introduction of the term 'metal atom cluster' by F. A. Cotton in inorganic chemistry, it is the good time to make a review on the advances in the engineering of molecular assemblies and nanomaterials based on octahedral Re6 metal atom clusters. The latter exhibit unique intrinsic structural and physicochemical properties (orthogonal disposition of metallic sites that can be selectively functionalized, photoluminescence, redox, generation of singlet oxygen) that make them relevant building blocks for the structuration at the nanometric scale and functionalization of hybrid organic-inorganic materials and supramolecular frameworks. After synthesis by solid state chemistry techniques at high temperature, inorganic precursors built up on face-capped [(Re6Yi8)Ya6] cluster units (Y = chalcogen and/or halogen) can be functionalized via solution chemistry techniques or organic melts to form [(Re6Yi8)La6] (L = CN, OH, various organic ligands...). This work reports advances in the synthesis of [(Re6Yi8)Ya6] and [(Re6Yi8)La6] cluster units as well as on their use in the elaboration of supramolecular frameworks, nanoparticles, hybrid nanomaterials (co-polymers and liquid crystals) and active molecular junctions

Electroswitchable red-NIR luminescence of ionic clustomesogen containing nematic liquid crystalline devices.

International audienceWe describe in this work several polyionic hybrid mol. compds. combining, by electrostatic interactions, liq. cryst. ammonium cations and tailor made molybdenum hexanuclear dianionic cluster units. All hybrids show nematic liq. cryst. behavior below 100 °C, no matter the nature of the metallic cluster apical and inner ligands. They also retain the shiny deep red photoluminescence properties of their parent cluster in the nematic phase. This nematic phase remains however quite viscous for all compds. and mixing them with com. available nematic LCs seems mandatory to integrate them into electroswitchable devices. This particularity conducted us to insert the best candidate in terms of homogeneity and stability of the clustomesogen/com. LC mixt. into a LC cell and study the behavior toward the application of an elec. stimulus. We show that the application of 30 V AC voltage allows observing a reversible modulation of the photoluminescence signal by about 52%. This work presents the first deep red photoluminescent transition metal cluster contg. device directed towards optoelectronic applications

Supramolecular Anchoring of Octahedral Molybdenum Clusters onto Graphene and Their Synergies in Photocatalytic Water Reduction

"This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acs.inorgchem.9b02529"[EN] Dihydrogen (H-2) production from sunlight should become one of the most important energy production means in the future. To reach this goal, low-cost and efficient photocatalysts still need to be discovered. Here we show that red near-IR luminescent metal cluster anions, once combined with pyrene-containing cations, are able to photocatalytically produce molecular hydrogen from water. The pyrene moieties act simultaneously as energy transmitters and as supramolecular linkers between the cluster anions and graphene. This association results in a hybrid material combining the emission abilities of pyrene and cluster moieties with the electronic conduction efficiency of graphene. Hydrogen evolution reaction (HER) studies show that this association induces a significant increase of H 2 production compared to that produced separately by clusters or graphene. Considering the versatility of the strategy described to design this photocatalytic hybrid material, transition-metal clusters are promising candidates to develop new, environmentally friendly, and low-cost photocatalysts for HER.The Severo Ochoa Program (SEV-2016-0683), Ministerio de Ciencia, Innovation y Universidades (PGC2018-099744), Consejo Superior de Investigaciones Cientificas (I-Link1063), and University of Rennes are thanked for financial support. We thank Dr. Marta Puche for her technical assistance with the preparation of dispersed graphene solutions at the ITQ.Feliz Rodriguez, M.; Atienzar Corvillo, PE.; Amela-Cortes, M.; Dumait, N.; Lemoine, P.; Molard, Y.; Cordier, S. (2019). Supramolecular Anchoring of Octahedral Molybdenum Clusters onto Graphene and Their Synergies in Photocatalytic Water Reduction. Inorganic Chemistry. 58(22):15443-15454. https://doi.org/10.1021/acs.inorgchem.9b02529S1544315454582

Octahedral molybdenum cluster as a photoactive antimicrobial additive to a fluoroplastic

Finding methods that fight bacterial infection or contamination, while minimising our reliance on antibiotics is one of the most pressing needs of this century. Although the utilisation of UV-C light and strong oxidising agents, such as bleach, are still efficacious methods for eliminating bacterial surface contamination, both methods present severe health and/or environmental hazards. Materials with intrinsic photodynamic activity (i.e. a material's ability upon photoexcitation to convert molecular oxygen into reactive oxygen species such as singlet oxygen), which work with light within the visible photomagnetic spectrum could offer a significantly safer alternative. Here we present a new, bespoke molybdenum cluster (Bu4N)2[Mo6I8(n-C7F15COO)6], which is both efficient in the generation of singlet oxygen upon photoirradiation and compatible with the fluoropolymer (F23-L) known for its good oxygen permeability. Thus, (Bu4N)2[Mo6I8(n-C7F15COO)6]/F23-L mixtures have been solution-processed to give homogenous films of smooth and fibrous morphologies and which displayed high photoinduced antibacterial activity against four common pathogens under visible light irradiation. These materials thus have potential in applications ranging from antibacterial coatings to filtration membranes and air conditioners to prevent spread of bacterial infections

Clustomesogens: Liquid Crystalline Hybrid Nanomaterials Containing Functional Metal Nanoclusters

International audienc

Assemblages (complémentarité de la chimie de coordination et de la chimie supramoléculaire)

Dans le but de synthétiser dans un premier temps un mimétique de l'anhydrase carbonique, nous décrivons les mimétiques de cette enzyme parus dans la littérature ainsi que les différentes méthodes de couplage d'acides aminés sur un macrocycle de type calixarène. Nous développons ensuite la synthèse de p-tert-butylcalix[4]arènes substitués régiosélectivement par 2, 3 ou 4 esters méthyliques de N[delta]-benzylHistidine. Après une approche structurale de leur caractérisation, l'étude des propriétés de complexation de ces ligands vis-à-vis du cobalt (II) et du zinc (II) est présentée indiquant par RMN et spectrométrie de masse une stœchiométrie 1:1 pour le dérivé trisubstitué avec le zinc (II). Ce complexe reproduit le site actif de la métalloenzyme avec la présence d'une cavité hydrophobe et d'un réseau de liaisons hydrogènes proche du site de complexation du cation. Dans une deuxième partie, les concepts d'autoassemblage et d'autorganisation sont abordés à travers la synthèse de récepteurs ditoptiques à base de calixarènes substitués sur la partie basse par des pyridines reliées par l'intermédiaire d'espaceurs de différentes tailles : la glycine, l'alanine et la lysine. Leur comportement en solution vis-à-vis du nickel (II) conduit à la formation de gel quelle que soit la concentration. La troisième partie traite des mêmes concepts avec la préparation d'un ligand pour lequel le calixarène est utilisé pour ses capacités préorganisatrices de systèmes chélatants. Quatre groupements terpyridiniques sont greffés sur la partie basse d'un p-tert-butylcalix[4]arène. Les propriétés de complexation de ce composé vis-à-vis du cobalt (II), du cuivre (II), du nickel (II) et du ruthénium (II) sont étudiées et révèlent dans chacun des cas une stœchiométrie M2L indiquant la formation d'un assemblage supramoléculaire. Plusieurs hypothèses d'assemblages sont discutées mettant en valeur la formation d'un dimère de type M4L2.LYON1-BU.Sciences (692662101) / SudocSudocFranceF