Rubbery organic frameworks-tuning the Gaz-diffusion through dynameric membranes

High permeability whilst keeping a reasonable selectivity is the most important challenge in developing membrane systems for gas separation. Valuable performances are usually obtained with polymeric membranes for which the gas transport is controlled by the gas-diffusivity in glassy polymers and by gas-solubility in rubbery polymers. During the last decade, important advances in this field are related to the molecular control of the gas separation properties. The combination/replacement of classical glassy polymers with metal-organic crystalline frameworks (MOFs, ZIFs, zeolites…) providing reasonable permeability through porous free volume network and high selectivity due to so-called “selectivity centers” specifically interacting with the gas molecules. Despite the impressive progress, important difficulties are observed to get dense mechanically stable thin layer MOFs on various supports. Taking advantage of high permeabilities observed with the rubbery polymers and to their flexible casting properties, there should be very interesting to build rubbery organic frameworks-ROFs, as alternative for gas membrane separation systems. Here we use low macromolecular constituents and dialdehyde core connectors in order to constitutionally generate rubbery organic. Differently to rubbery polymeric membranes the ROFs performances depend univocally of diffusional behaviors of gas molecules through the network. For all gases, a precise molecular composition of linear and star-type macromonomers generates an optimal free volume for a maximal diffusion through the matrix. These results should initiate new interdisciplinary discussions about highly competitive systems for gas separation, constitutionally controlled at the molecular scale. Please click Additional Files below to see the full abstract

Salt-excluding artificial water channels exhibiting enhanced dipolar water and proton translocation

Aquaporins (AQPs) are biological water channels known for fast water transport (~108-109 molecules/s/channel) with ion exclusion. Few synthetic channels have been designed to mimic this high water permeability, and none reject ions at a significant level. Selective water translocation has previously been shown to depend on water-wires spanning the AQP pore that reverse their orientation, combined with correlated channel motions. No quantitative correlation between the dipolar orientation of the water-wires and their effects on water and proton translocation has been reported. Here, we use complementary X-ray structural data, bilayer transport experiments and molecular dynamics (MD) simulations to gain key insights and quantify transport. We report artificial imidazole-quartet water channels with 2.6-Å pores, similar to AQP channels, that encapsulate oriented dipolar water-wires in a confined chiral conduit. These channels are able to transport ~106 water molecules per second, which is within two orders of magnitude of AQPs’ rates, and reject all ions except protons. The proton conductance is high (~5 H+/s/channel) and approximately half that of the M2 proton channel at neutral pH. Chirality is a key feature influencing channel efficiency. Please click Additional Files below to see the full abstract

Bis[μ-1-hexyl-3-(2,3,5,6,8,9,11,12-octa­hydro-1,4,7,10,13-benzopenta­oxacyclo­penta­decin-15-yl)urea]bis­(azido­sodium) chloro­form disolvate

In the title compound, [Na2(N3)2(C21H34N2O6)2]·2CHCl3, the sodium cation is hepta­coordinated by five O atoms of the crown ether unit of the 1-hexyl-3-(2,3,5,6,8,9,11,12-octa­hydro-1,4,7,10,13-benzopenta­oxacyclo­penta­decin-15-yl)urea (L) ligand, the O atom of the urea group of the second, symmetry-related L ligand, and one N atom of the azide anion. The experimentally determined distance 2.472 (2) Å between the terminal azide N atom and the sodium cation is substanti­ally longer than that predicted from density functional theory (DFT) calculations (2.263 Å). The crown ethers complexing the sodium cation are related by an inversion centre and form dimers. The urea groups of the two L ligands are connected in a head-to-tail fashion by classical N—H⋯N hydrogen-bonding inter­actions and form a ribbon-like structure parallel to the b axis. Parallel ribbons are weakly linked through C—H⋯N, C—H⋯O and C—H⋯π inter­actions

Self-assembly of supramolecular triarylamine nanowires in mesoporous silica and biocompatible electrodes thereof

Biocompatible silica-based mesoporous materials, which present high surface areas combined with uniform distribution of nanopores, can be organized in functional nanopatterns for a number of applications. However, silica is by essence an electrically insulating material which precludes applications for electro-chemical devices. The formation of hybrid electroactive silica nanostructures is thus expected to be of great interest for the design of biocompatible conducting materials such as bioelectrodes. Here we show that we can grow supramolecular stacks of triarylamine molecules in the confined space of oriented mesopores of a silica nanolayer covering a gold electrode. This addressable bottom-up construction is triggered from solution simply by light irradiation. The resulting self-assembled nanowires act as highly conducting electronic pathways crossing the silica layer. They allow very efficient charge transfer from the redox species in solution to the gold surface. We demonstrate the potential of these hybrid constitutional materials by implementing them as biocathodes and by measuring laccase activity that reduces dioxygen to produce water

Artificial Water Channels toward biomimetic membranes for desalination, Keynote Lecture

International audienc

Artificial Water Channels toward biomimetic membranes for desalination

International audienc

Artificial Water Channels toward biomimetic membranes for desalination, Keynote Lecture

International audienc

Canaux artificiels d'eau : des membranes biomimétiques pour le dessalement

International audienceCanaux artificiels d'eau : des membranes biomimétiques pour le dessalement Résumé : Le dessalement de l'eau de mer est un défi économique important. Un des procédés industriels actuels utilise l'osmose inverse (sous pression) avec des membranes constituées d'une mince couche de polyamide, mais ceci est coûteux et énergivore. Nous développerons ici les progrès réalisés depuis une dizaine d'années avec la fabrication de membranes biomimétiques principalement destinées au dessalement de l'eau de mer. La découverte des canaux de protéines naturelles comme les aquaporines permettant le transport de l'eau a été suivie de nombreuses recherches sur l'élaboration de membranes synthétiques avec des incorporations de canaux artificiels d'eau, mimant la nature dans des membranes polymères stables et conduisant à des procédés plus rentables et respectant davantage l'environnement