Surface integration of molecular catalysts inspired from the active sites of hydrogenase enzymes represents a promising route towards developing noble metal-free and sustainable technologies for H2 production. Efficient and stable catalyst anchoring is a key aspect to enable this approach. Herein, we report the preparation and electrochemical characterization of an original diironhexacarbonyl complex including two pyrene groups per catalytic unit in order to allow for its smooth integration, through π-interactions, onto multiwalled carbon nanotube-based electrodes. In this configuration, the grafted catalyst could reach turnover numbers for H2 production (TONH2) of up to 4±2×103 within 20 h of bulk electrolysis, operating at neutral pH. Post operando analysis of catalyst functionalized electrodes revealed the degradation of the catalytic unit occurred via loss of the iron carbonyl units, while the anchoring groups and most part of the ligand remained attached onto multiwalled carbon nanotubes. 相似文献
In Hevea, rubber synthesis is confined to the cytosol of the highly differentiated laticifer cells. Agronomic and biochemical studies showed that this process uses high amounts of sugars that are efficiently imported into the laticifer. A H(+)-sugar symport system located in the plasma membrane is involved in sugar uptake into laticifers. Laticifer protoplasts were prepared and used in electrophysiological and labeling experiments to test the capacity of this system to transport a variety of sugars such as oligosaccharides from the raffinose family, trace compounds in rubber. Translocation of sugars known to be transported with different efficiency across the plasma membrane of plant cells was also tested. A 1 mM sucrose affinity was found for the symport. All the sugars tested, except palatinose induce membrane depolarization indicating that they were actively absorbed by the laticifer network. This reveals the wide capacity of this peculiar sink for the uptake of sugars. 相似文献
A poly(tert‐butyl acrylate) (P(tBA)) with a glycodendric endfunctionality with eight glucose moieties was synthesised in four steps via a combination of esterification, thiol‐alkyne conjugation and hetero‐Diels–Alder (HDA) cycloaddition. A linear glycopolymer of similar size and composition was also synthesised in order to compare the protein binding characteristics of the polymer with glycodendritic endfunctionality to the linear glycol blockcopolymer. The two amphiphilic polymers were self‐assembled in water into micelles. These particles were then tested for their ability to bind to Concanavalin A (Con A). In a turbidity assay, the polymer glycodendron exhibited a significantly faster clustering rate to the lectin as compared to the linear glycopolymer. In a precipitation assay, it is found that significantly less glucose residue is required for binding per Con A for the polymer with the glycodendritic endfunctionality.
An efficient methodology for synthesis of isoindoloisoquinoline 5a and isoindolobenzazepine 5b in oxidized forms as tetracyclic alkaloids cores are reported from N-bromoethylphthalimide (6) or phthalic anhydride and 2-phenylthioethylamine (8) in a five- or six-step sequence, respectively, in overall very good yields. The key step of this methodology is based on an intramolecular π-cationic cyclization of the thionium ion species. Alternatively, another four-step route was explored and based in an ultimate step on the cyclodehydration of an aldehyde functionality, which used as intermediate in the latest strategy, via the oxonium ion cation. 相似文献
A Passerini three component condensation between a carboxylic acid, an aldehyde, and an isocyanide at high temperature under solvent-free conditions was developed. This methodology allows the formation of a broad range of α-acyloxyamides in excellent yields in short reaction times. 相似文献
The synthesis of isobrassilexin 2, a hitherto non natural indoloisothiazole is reported (two steps, 43% yield). This substance, an isomer of brassilexin 1 has shown important biological properties in vitro. 相似文献
We use symmetry analysis to show that the G-, C-, and A-type antiferromagnetic Pnma perovskites can exhibit magnetoelectric (ME) responses when a ferroelectric instability is induced with epitaxial strain. Using first-principles calculations we compute the values of the allowed ME response in strained CaMnO_{3} as a model system. Our results show that large linear and non-linear-ME responses are present and can diverge when close to the ferroelectric phase transition. By decomposing the electronic and ionic contributions, we explore the detailed mechanism of the ME response. 相似文献