ChemSusChem最新文献

We here report the synthesis of two types of six-membered cyclic carbonate monomers equipped with various drug molecules through ester linkages. The target compounds can be isolated in good yields and feature diagnostic IR and 13C NMR spectroscopic fingerprints in line with their proposed connectivities. As a potential application, we investigated their ring-opening polymerization (ROP), showing that the nature of the cyclic carbonate is crucial towards macromolecular carbonate formation. The functionalized polycarbonates have molecular weights of up to 10 kg/mol, controllable functionality and a variable drug-to-carbonate ratio. This work demonstrates the adaptive synthesis of new types of functionalized six-membered cyclic carbonates with potential as precursors to polycarbonate-drug type macromolecules.

Zeolites are a group of crystalline aluminosilicates with exchangeable cations and molecular-dimensioned micropores, which have successfully been applied to transform biomass and waste into biofuels. Herein, the effectiveness of acidic H-zeolites in biomass transformation and chemical valorization is demonstrated. In this process, the Brønsted/Lewis acid sites in zeolites catalyze the transition of carbohydrates into valuable chemicals. β-glucan polymer extracted from the lichen Usnea was catalytically converted into value-added molecules, such as glucose monomers. Particular challenges to elucidate the zeolite-catalyzed β-glucan conversion to glucose were addressed, namely: (i) water as the solvent, ii) hydrolysis of the biopolymer in an ionic liquid of 1-Butyl-3-vinylimidazolium bromide ([BVinIm]Br), and iii) reaction time of 30, 60, 120, and 240 min. Effective hydrolysis of β-glucan was achieved by H-zeolites (H-Beta, H-Mordenite, and H-ZSM-5), and the formed glucose was quantified through the dinitrosalicylic acid (DNS) method. Finally, applying H-zeolites as heterogeneous catalysts to prove the chemical recyclability of flexible films based on β-glucan was demonstrated as a step forward in integrating biopolymer-based materials into the circular economy.

N,N-dimethylformamide (DMF) and trifluoroacetic acid (TFA) are the two solvents/reagents most widely used in solid-phase peptide synthesis (SPPS).  While DMF is already regulated in Europe, TFA-a member of the polyfluoroalkyl substances (PFAS) family-is expected to face similar restrictions soon.  These compounds break down slowly and pose risks to human health and the environment.  Herein, the use of the so-called "green acid par excellence", methanesulfonic acid (MSA), in substitution of TFA is discussed.  As MSA is stronger than TFA, it is diluted with a solvent for use. The effectivity of MSA depends on the solvents used.  When dichloromethane (DCM) is used, 1.5% MSA removes all side-chain protecting groups, except the trityl (Trt) group of His.   In the presence of acetic acid (AcOH) and dimethylcarbonate (DMC), more concentrated solutions of MSA (8-16%) are required.  The removal of the Trt group of Asn/Gln continues to be a challenge even with these solutions, and aspartimide formation can occur in Asp-containing peptides.

The abatement of aromatic pollutants in water requires their oxidation to nontoxic products by resource-intensive reactions with hydroxyl radicals (•OH). We elucidate the mechanisms of •OH-induced aromatic ring degradation by combining kinetic measurements, electron paramagnetic resonance spectroscopy, density functional theory calculations, and kinetic modelling. We demonstrate that benzyl alcohol, a model aromatic compound, is oxidized by •OH radicals, generated by ultrasonic irradiation in an O2-rich environment, into aromatic compounds (benzaldehyde and phenol derivatives) and C1-C2 oxygenates (formic acid, glyoxal, and oxalic acid). Through pathways akin to atmospheric chemistry, these •OH radicals de-aromatize and fragment benzyl alcohol, producing 5-hydroxy-4-oxo-pentenal and other dicarbonyl products. Unique to the aqueous phase, however, superoxide (•O2-) forms by •OOH deprotonation, which is generated by ultrasound (alongside •OH) and as a byproduct of •OH-benzyl alcohol reactions. •O2- acts as a nucleophile, oxidizing 5-hydroxy-4-oxo-pentenal into oxalic acid and C1 oxygenates via aldehyde and ketone intermediates. This process regenerates •O2- and does not consume •OH, thereby further degrading ring fragmentation products while preserving •OH to activate the refractory aromatic ring of benzyl alcohol. These nucleophilic •O2-reactions can therefore reduce the energy and number of chemical initiators needed to degrade aromatic compounds, thus advancing •OH-based oxidation processes in water treatment.

Redox-active covalent organic frameworks (COFs) with metal binding sites are increasingly recognized for developing cost-effective, eco-friendly organic electrodes in rechargeable energy storage devices. Here, we report a microwave-assisted synthesis and characterization of a triazine-based polyimide COF that features dual redox-active sites (-C=O from pyromellitic and -C=N- from triazine) and COF@CNT nanocomposites (COF@CNT-X, where X=10, 30, and 50 wt % of NH₂-MWCNT) formed through covalent linking with amino-functionalized multiwalled carbon nanotubes. These composites are evaluated as cathode materials for the sodium-ion batteries (SIBs). The amine functionalization renders the covalent bond between COF and CNT, improving electronic conductivity, structural rigidity, and long-term stability. The interfacial growth of COF layers on CNTs increases accessible redox-active sites, enhancing sodium diffusion kinetics during sodiation/desodiation. The COF@CNT-50 composite exhibits outstanding Na⁺ ion storage performance (reversible capacity of 164.3 mAh g^-1 at 25 mA g^-1) and excellent stability over 1000 cycles at ambient temperature. At elevated temperature (65 °C), it also maintains good capacity and cycle stability. Ex situ XPS analysis confirms the importance of dual active sites in the Na⁺ diffusion mechanism. Density functional theory (DFT) calculations reveal insights into Na⁺ binding sites and corresponding binding energies into COF structure, elucidating the experimental storage capacity and voltage profile.

A donor-acceptor-donor (D-A-D) molecule, denoted as RC18, consisting of two nickel-porphyrin  terminal donor units (D) and a selenophene-flanked diketopyrrolopyrrole central core, connected via  an ethynylene linker has been synthesized. The highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels were measured showing values of -5.49 eV and -3.75 eV, respectively. We have utilized RC18 as donor along with two acceptors, DICTF and Y6, for OSCs and found that power conversion efficiencies were 12.10% and 12.59% for RC18:DICTF and RC18:Y6, respectively. The complementary absorption profiles of RC18, DICTF and Y6, along with the intermediate LUMO level of DICTF between RC18 and Y6, led to the fabrication of ternary organic solar cells. RC18:DICTF:Y6 based ternary attained  power conversion efficiency of 16.06%. The observed enhancement in the PCE is attributed to efficient exciton utilization through energy transfer from DICTF to Y6, increased donor-acceptor interfacial area, suppressed charge carrier recombination and improved molecular ordering. These all factors contribute  to improvements in short-circuit current density (JSC) and fill factor (FF). Additionally, the open-circuit voltage (VOC) of the ternary OSC lies between those of the two binary OSCs indicating the formation of an alloy between the two acceptors.

Cost-effective and efficient photoelectrochemical (PEC) water splitting stands out as one of the most promising strategies to address sustainable energy supply in the form of green H2. Large-area photoelectrodes featuring precise chemical and morphological control are key components for a practical solar-to-hydrogen conversion. Herein, we report the continuous flow synthesis of BiVO4 nanoparticles (NPs) by using a simple microreactor configuration. The solution containing the as-prepared NPs enables the deposition of BiVO4 photoanodes with areas up to 52 cm2 through a simple and scalable chemical bath deposition method. On the other hand, surface protection by an ultrathin Al2O3 overlayer grown by atomic layer deposition (ALD) increases the performance of the 1 cm2 BiVO4 photoanodes ~ 30%, exhibiting a photocurrent density of ~2.0 mA·cm-2 at 1.23 V vs. the Reversible Hydrogen Electrode in the presence of a sacrificial hole scavenger. The optimized continuous flow synthesis provides an affordable methodology for the fabrication of cost-effective, large-scale photoanodes, which could potentially be applied for different photoelectrochemical reactions.

Atom- and energy-efficient chemical separations are urgently needed to meet the surging demand for critical materials that has strained supply chains and threatened environmental damage. In this study, we used reaction-diffusion coupling to separate iron, neodymium, and dysprosium ions from model feedstocks of permanent magnets, which are typically found in electronic wastes. Feedstock solutions were placed in contact with a hydrogel loaded with potassium hydroxide and/or dibutyl phosphate, resulting in complex precipitation patterns as the various metal ions diffused into the reaction medium. Specifically, we observed the precipitation of up to 40 mM of iron from the feedstock, followed by the enrichment of 73% dysprosium, and the extraction of >95% neodymium product at a further distance from the solution-gel interface. We designed a series of experiments and simulations to determine the relevant ion diffusivities, DNd = 5.4×10-10 and DDy = 5.1×10-10 m2/s, and precipitation rates, kNd = 1.0×10-5 and kDy = = 5.0×10-3 m9mol-3s-1, which enabled a numerical model to be established for predicting the distribution of products in the reaction medium. Our proof-of-concept study validates reaction-diffusion coupling as an effective and versatile approach for critical materials separations, without relying on ligands, membranes, resins, or other specialty chemicals.

A key challenge for sorbent-mediated temperature-swing direct air capture remains to maximize the difference in CO2 loading under capture and regeneration conditions (i.e. the working capacity) while minimizing the thermal energy input required to alternate between the two equilibrium states. Herein, peralkylated guanidines were shown to capture close to 1 molar equivalent (or up 4.5 mol CO2/kg absorbent) directly from moist air (>60% RH) at room temperature and completely release the entire quantity of captured CO2 upon co-evaporation of water at 70 oC affording concentrated CO2 with a vapor content of 3 mol% and achieving a high working capacity with minimum temperature swing of 45 oC.

Dual-ion batteries are attracting much attention due to the joint participation of anions and cations in the energy storage process. However, this unique battery configuration imposes high demands on the cathode, which typically presents an inferior rate performance. Herein, we employ graphite in different microcrystalline sizes as cathodes, associated with high concentration electrolyte to construct sodium dual-ion batteries. The results of in-situ XRD and Raman evidence that the surface effect is enhanced by suitably small graphite microcrystals, where a greater surface involvement affords more electro-activated regions for the ions. Furthermore, the analysis of sputtering XPS confirms that the PF6- is accompanied by the co-intercalation of Na+ into cathodes by constructing the model of concentration effect, thus accelerating the kinetic process. In conclusion, the co-intercalation of PF6- together with Na+ is demonstrated under the influence of enhanced surface concentration effect in cathodes, and thus the cathodes exhibit a superior rate performance with a capacity of 103.6 mAh g-1 at a rate of 2 C and a rate retention of 94.8% even at 50 C. This work provides new insights to explain the mechanism of ion intercalation in dual-ion batteries and offers a perspective for the construction of high energy storage systems.