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Redox mediators (RMs) are considered an effective countermeasure to reduce the large polarization in lithium–oxygen batteries. Nevertheless, achieving sufficient enhancement of the cyclability is limited by the trade–offs of freely mobile RMs, which are beneficial for charge transport but also trigger the shuttling phenomenon. Here, we successfully decoupled the charge–carrying redox property of RMs and shuttling phenomenon by anchoring the RMs in polymer form, where physical RM migration was replaced by charge transfer along polymer chains. Using a model system of a polymer, PTMA (2,2,6,6–tetramethyl–1–piperidinyloxy–4–yl methacrylate), based on the well–known RM tetramethylpiperidinyloxyl (TEMPO), it is demonstrated that PTMA is capable o.
Expanded porphyrins with proper metalation provided us with an excellent opportunity to study excited‐state aromaticity. The coordinated metal helped us to observe the excited‐state aromaticity in the triplet state by the heavy atom effect, but other metalation effects on the excited‐state aromaticity were ambiguous. Here, the excited‐state aromaticity of gold(III) hexaphyrins through the relaxation dynamics was revealed via the electronic and vibrational spectroscopy. The S Q states of gold [26]‐ and [28] hexaphyrins showed interconvertible absorption and IR spectra with those of counterparts in the ground‐state, indicating aromaticity reversal. Furthermore, while the T 1 states of gold [28] hexaphyrins also exhibited reversed aromaticity
Transition metal‐catalyzed direct asymmetric reductive amination (ARA) of diaryl or sterically hindered ketones remains unknown and an open challenge. Herein, Ru‐catalyzed direct asymmetric reductive amination of ortho ‐OH‐substituted diaryl and sterically hindered ketones with ammonium salts has been disclosed for the first time, offering a straightforward route toward the synthesis of synthetically useful chiral primary diarylmethylamines and sterically hindered benzylamines (up to 97% yield, 93−>99% ee). The elaborations of chiral amine products into bioactive compounds have been exhibited through manipulations on the removable and convertible ‐OH group. Moreover, gram‐scale synthesis of chiral sterically bulky amine 6ac and its applicat.
The 60‐year high Bordetella pertussis ( B. pertussis ) infection rate in the world suggests the urgent need for new anti‐pertussis vaccines. Lipopolysaccharide (LPS) of B. pertussis is an attractive antigen for vaccine development. With the presence of multiple rare sugars and unusual glycosyl linkages, B. pertussis LPS is a highly challenging synthetic target. In this work, aided by molecular dynamics simulation and modeling, the pertussis LPS like pentasaccharide was chemically synthesized for the first time. The pentasaccharide was conjugated with a powerful carrier, bacteriophage Qβ as a vaccine candidate. Immunization of mice with the conjugate induced robust anti‐glycan IgG responses with IgG titers reaching several million enzyme‐lin.
Materials for the controlled release of nitric oxide (NO) are of interest for therapeutic applications. However, to date, many suffer from toxicity and stability issues, as well as poor performance. Herein, we propose a new NO adsorption/release mechanism through the formation of nitrites on the skeleton of a titanium‐based Metal‐Organic Framework (MOF) that we have named MIP‐177, featuring a suitable set of properties for such applications: (i) high NO storage capacity (3 µmol mg ‐1 solid ), (ii) excellent biocompatibility at therapeutic relevant concentrations (no cytotoxicity at 90 µg/mL for wound healing) due to its high stability in biological media ( < 9% degradation in 72 hours) and (iii) slow NO release in biological media (⁓2 hours.
The conjugation of hydrophilic low‐fouling polymers to therapeutic molecules and particles is an effective approach to improving their aqueous stability and solubility, and extending their pharmacokinetics. Recent concerns over the immunogenicity of poly(ethylene glycol) has highlighted the importance of identifying alternative low fouling polymers. Herein, we report a new class of synthetic water‐soluble homo‐fluoropolymers with a sulfoxide side‐chain structure. The incorporation of fluorine enables direct imaging of the homopolymer by 19 F MRI, negating the need for additional synthetic steps to attach an imaging moiety. These self‐reporting fluoropolymers show outstanding imaging sensitivity and as such represent a new class of low‐fouli.
The first isolated examples of intermolecular oxidative addition of alkenyl and alkynyl iodides to Au(I) are reported. Using a 5,5ʹ‐difluoro‐2,2ʹ‐bipyridyl ligated complex, oxidative addition of geometrically defined alkenyl iodides occurs readily, reversibly and stereospecifically to give alkenyl‐Au(III) complexes. Conversely, reversible alkynyl iodide oxidative addition generates bimetallic complexes containing both Au(III) and Au(I) centers. Stoichiometric studies show that both new initiation modes can form the basis for the development of C−C bond forming cross‐couplings.
The production of high purity toluene and pyridine is of significance in both industrial production and synthetic chemistry. The present protocols available to separate toluene/pyridine mixtures are several energy‐intensive distillation methods, which are not environmently‐friendly and cost‐effective. Here we provide an energy‐efficient and simple adsorptive separation protocol using nonporous adaptive crystals of cucurbit[6]uril ( Q[6] ). Q[6] crystals separate pyridine from toluene/pyridine mixtures with nearly 100% purity. Furthermore, removal of guest from guest‐loaded Q[6] leads to the guest‐free cucurbit[6]uril, which can be recycled without losing performance.
Metal‐organic frameworks (MOFs) are emerging as leading candidates for nanoscale drug delivery, as a consequence of their high drug capacities, ease of functionality, and the ability to carefully engineer key physical properties. Despite many anticancer treatment regimens consisting of a cocktail of different drugs, examples of delivery of multiple drugs from one MOF are rare, potentially hampered by difficulties in postsynthetic loading of more than one cargo molecule. Herein, we report a new strategy, multivariate modulation, which allows incorporation of up to three drugs in the Zr MOF UiO‐66 by defect‐loading. The drugs are added to one‐pot solvothermal synthesis and are distributed throughout the MOF at defect sites by coordination at
The stereoselective formation of 1,2‐ cis ‐glycosidic bonds is challenging. However, 1,2‐ cis ‐selectivity can be induced by remote participation of C4 or C6 ester groups. Reactions involving remote participation are believed to proceed via a key ionic intermediate, the glycosyl cation. Although mechanistic pathways were postulated many years ago, the structure of the reaction intermediates remained elusive due to their short‐lived nature. Here, we unravel the structure of glycosyl cations involved in remote participation reactions via cryogenic vibrational spectroscopy and first principles theory. Acetyl groups at C4 ensure α‐selective galactosylations by forming a covalent bond to the anomeric carbon in dioxolenium‐type ions. Unexpectedly.
Residual dipolar couplings (RDCs) are amongst the most powerful NMR parameters for organic structure elucidation. In order to maximize their effectiveness in increasingly complex cases such as flexible compounds, a maximum of RDCs between nuclei sampling a large distribution of orientations is needed, including sign information. For this, the easily accessible one‐bond 1 H‐ 13 C RDCs alone often fall short. Long‐range 1 H‐ 1 H RDCs are both abundant and typically sample highly complementary orientations, but accessing them in a sign‐sensitive way has been severely obstructed due to the overflow of 1 H‐ 1 H couplings. Here, we present a generally applicable strategy that allows the measurement of a large number of 1 H‐ 1 H RDCs, including th.
The energy of visible photons and the accessible redox potentials of common photocatalysts set thermodynamic limits to photochemical reactions that can be driven by traditional visible‐light irradiation. UV excitation can be damaging and induce side reactions, hence visible or even near‐IR light is usually preferable. Thus, photochemistry currently faces two divergent challenges, namely the desire to perform ever more thermodynamically demanding reactions with increasingly lower photon energies. The pooling of two low‐energy photons can address both challenges simultaneously, and whilst multi‐photon spectroscopy is well established, synthetic photoredox chemistry has only recently started to exploit multi‐photon processes on the preparative.
Herein, we report the molecular‐level structuration of two full photosystems into conjugated porous organic polymers. The strategy of heterogenization gives rise to photosystems which are still fully active after 4 days of continuous illumination. Those materials catalyse the carbon dioxide photoreduction driven by visible light to produce up to three grams of formate per gram of catalyst. The covalent tethering of the two active sites into a single framework is shown to play a key role in the visible light activation of the catalyst. The unprecedented long‐term efficiency arises from an optimal photoinduced electron transfer from the light harvesting moiety to the catalytic site as anticipated by quantum mechanical calculations and evidenc.
The evolution of coenzymes, or the impact of coenzymes on the origin of Life, is fundamental for understanding our own existence and yet, this topic is rarely discussed in contemporary science. Coenzymes are small molecules that occupy an elementary role with respect to chemical reactivity and selectivity when associated with a macromolecular template. They are essential for functional biocatalysis in all living organisms and act as currency to regulate many basic metabolic processes. Having established reasonable hypotheses about the emergence of prebiotic chemical building blocks, which were probably created under palaeogeochemical conditions, and surmising that these smaller compounds must have become integrated to afford complex macromo.
We report a nickel hydride‐catalyzed migratory defluorinative coupling between two electronically‐differentiated olefins. A broad scope of unactivated donor olefins can be joined directly to acceptor olefins containing an electron‐deficient trifluoro‐methyl‐substituent in both intra‐ and intermolecular fashions to form gem ‐difluoroalkenes. This migratory coupling has both site‐ and chemoselectivity under mild conditions, with the formation of a tertiary or quaternary carbon center.
We report herein a series of pore‐containing polymeric nanotubes based on an H‐bonded hydrazide backbone. Nanotubes of suitable lengths, possessing a hollow cavity of ~ 6.5 Å in diameter, are interestingly found to mediate highly efficient transport of diverse types of anions, rather than cations, across lipid membrane. Polymer channel 1a , having an averaged molecular weight of 18.2 KDa and 3.6 nm in helical height, exhibits the highest anion transport activities with iodide ( EC 50 = 0.042 uM or 0.028 mol% relative to lipid) being transported 10 times more efficiently than chlorides ( EC 50 = 0.47 uM). Notably, even in cholesterol‐rich environment, iodide transport activity still remains high with EC 50 of 0.37 uM. Molecular dynamics simu.
Cost‐effective carbon‐based catalysts are promising for catalyzing electrochemical N 2 reduction reaction (NRR). However, the activity origin of carbon‐based catalysts towards NRR remains unclear, and regularities and rules in rational design carbon‐based NRR electrocatalysts are still lacking. Here, based on a combination of theoretical calculations and experimental observations, we systematically evaluated the chalcogen/oxygen group elements (O, S, Se, and Te) doped carbon materials as potential NRR catalysts. We revealed that heteroatom‐doping induced charge accumulation facilitates N 2 adsorption on carbon atom and spin polarization boosts the potential‐determining step of the first protonation to form *NNH. Te and Se‐doped C catalysts
Membrane‐based reverse electrodialysis (RED) is considered as the most promising technique to harvest osmotic energy. However, the traditional membranes are limited by the high internal resistance and low efficiency, resulting in undesirable power densities. Here, we report the combination of oppositely charged Ti 3 C 2 T x MXene membranes (MXMs) with confined 2D nanofluidic channels as high‐performance osmotic power generators. The negatively or positively charged 2D MXene nanochannels exhibit typical surface‐charge‐governed ion transport and show excellent cation or anion selectivity. By mixing the artificial sea water (0.5 M NaCl) and river water (0.01 M NaCl), we obtain a maximum power density of ~4.6 W m −2 , higher than most of the st.
For in‐situ resource utilization (ISRU), the cost‐mass conundrum needs to be solved, before any other formidable challenges may be tackled. Technologies may need to be conceptualised from first principals, rather than taking the most advanced technology of today. Using this approach, this paper seeks to provide a think tank about how chemical process intensification can help with technology and business case disruption of ISRU matters, how this might influence Space‐industry start‐ups, and first of all even Earth‐industry transformations. The disruptive technology considered is continuous micro‐flow solvent extraction and, as another disruptive element therein, the use of ionic liquids (instead of conventional organic solvents). The Space b.

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