ACS Publications最新文献

In this work, a series of high-performance organic light-emitting devices based on blue thermally activated delayed fluorescence material DBA-DI were designed and fabricated by utilizing the gadolinium(III) complex as a hole trapper. After optimizing the doping concentration of the blue emitter, the Gd complex was codoped into the emitting layer (EML). Due to the high-lying highest occupied molecular orbital level (HOMO) of the Gd complex, superfluous holes within EML were effectively captured, thus improving carrier balance and broadening the recombination zone. Experimental results demonstrated that the codoped devices obtained significantly elevated electroluminescent (EL) performance by regulating carrier distribution and suppressing exciton quenching. Compared with nonco-doped devices, codoped devices displayed higher external quantum efficiency (EQE) and brightness with increased ratios of nearly 20% and over 30%, respectively. Eventually, the optimal codoped double-EML device obtained the maximum EQE, brightness, current efficiency, and power efficiency as high as 15.82%, 12,170 cd m^–2, 27.47 cd A^–1, and 31.96 lm W^–1, respectively. In addition, by further optimizing the thickness of the electron transport layer, a maximum EQE as high as 17.49% was realized.

The catalytic hydrodeoxygenation (HDO) of lignocellulose-derived pyrolysis oil is a critical process for producing high-quality biofuels. This study investigates the effect of the Mg/Al molar ratio on the catalytic performance of CuMg(Al)O mixed oxide catalysts in the HDO reaction of benzyl alcohol as a model oxygenated compound. They were synthesized by coprecipitation with a fixed Cu content of 15 at. %, with respect to cations, and different Mg/Al molar ratios (0/1, 1/1, 3/1, 5/1, and 1/0). The catalysts were characterized using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), UV–vis spectroscopy, nitrogen adsorption–desorption isotherms, temperature-programmed reduction with hydrogen (H₂-TPR), and temperature-programmed desorption (TPD) of CO₂ and NH₃. It has been shown that the Mg/Al molar ratio strongly influences the physicochemical characteristics of the CuMg(Al)O mixed oxides and, hence, their catalytic performance. Catalytic tests were conducted in a stainless-steel autoclave reactor and the obtained results indicated that the systems with Mg/Al molar ratios of 3/1 and 5/1, issued from layered double hydroxide precursors, exhibited the highest activity, with yields to toluene higher than 85%. This superior performance is attributed to the well-dispersed copper species on the catalyst surface combined with appropriate acid–base properties. As the CuMg(Al)O system with Mg/Al molar ratio of 5/1 was the best in terms of benzyl alcohol conversion, i.e., ca. 98% at 230 °C, under 5 atm of H₂, for 3 h of reaction time, with high selectivity to toluene of ca. 87%, the influence of the reaction time, temperature and reusability over multiple reaction cycles on its performance were investigated.

Natural polyphenols can be oxidized into reactive quinones, which might play a key role in the removal of specific contaminants in natural polyphenol-related advanced oxidation processes (AOPs). In this study, peracetic acid (PAA) was employed in combination with natural protocatechuic acid (PCA) to remove sulfonamide antibiotics (SAs) from water. More than 95% removal of sulfamethoxazole (SMX) and other SAs was observed in the PCA/PAA system, and neutral pH conditions (5.0–8.0) were more conducive to the removal of SMX. The PCA/PAA system exhibited a great anti-interference ability against complex water matrices. ortho-Quinone, generated from the oxidation of PCA by PAA, played a dominant role in the SMX removal. Electrons tended to transfer from SMX to the generated ortho-quinones and form covalent bonds, resulting in the production of less toxic oligomers via the overlooked polymerization pathway. A reduction in the toxicity of the SMX solution was found following treatment with the PCA/PAA system. More interestingly, several polyphenols structurally related to PCA could also facilitate SMX removal using PAA as the oxidant. Overall, this study proposes a novel strategy for developing reactive quinones dominated AOPs with robust anti-interference performance, as well as enhances the understanding of contaminant removal via an overlooked polymerization pathway in natural polyphenol-related AOPs.

This study explores the endo-levanase from Bacillus licheniformis (LevB1), providing new insights into how this enzyme selectively hydrolyzes levan chains. By analyzing the first resolved crystal structure of LevB1, conducting detailed simulations, and comparing it to other endo- and exo-fructanases, we identified key factors underlying its specificity. Experiments designed to explore this specificity revealed the critical role of three minus and three plus subsites in determining the enzyme’s endo-specificity. We identified six specific subsites essential for the enzyme’s ability to cleave levan chains at random internal linkages (endo-specificity) rather than at defined fructosyl nonreducing ends (exo-specificity). This research underscores the importance of enzyme–fructan interaction stability during the catalytic reaction in this process, highlighting the need for dynamic modeling to fully capture enzyme specificity, as conventional docking alone cannot fully explain the stability and motion of carbohydrate chains in the catalytic site. These findings contribute to a deeper understanding of the factors that influence endo- and exo-cleavage specificity in levan and inulin polymers, with broader implications for fructan metabolism and, eventually, the industrial production of fructose and/or fructo-oligosaccharides.

The role of endophytic bacterial communities in aiding the degradation of organic pollutants like phthalates (PAEs) in soil and in planta, as well as their effects on pollutant accumulation in plants, remains unclear. Herein, microcosm experiments were conducted with rice cultivated in agricultural soil polluted with di(2-ethylhexyl) phthalate (DEHP) and further verified with PAE-degrading endophytic consortia. Soil indigenous microbes, especially PAE-degrading bacteria, significantly contributed to DEHP dissipation in soil and diminished DEHP accumulation in rice. Endophytic bacterial communities participated in DEHP degradation in planta, as validated by efficient DEHP degradation by in vitro culturable endophytic consortia and abundant PAE-degrading genes. The inoculation of PAE-degrading endophytic consortia demonstrated their immigration between soil and roots (especially in low-PAE-accumulating cultivar), which enhanced DEHP degradation in soil and in planta and subsequently reduced rice PAE accumulation. This study underscores the facilitative role of endophytic bacterial communities in PAE degradation and in lowering PAE accumulation in crops.

Medical catheters require lubrication and antimicrobial properties to reduce complications, such as tissue trauma and bacterial infections. Coating hydrogel on the catheter surface is a promising strategy; however, it usually faces the challenge of weak interfacial adhesion, thus leading to coating delamination or fracture and failure. Here, a waterborne polyurethane (WPU)-triggered surface bonding strategy was presented to construct hydrogel coatings, which involved two key steps: (i) coating a sticky WPU layer on the catheter surface and (ii) dip-coating the WPU-coated catheter with a monomer solution consisting of quaternary ammonium chitosan (QCS), sulfobetaine methacrylate (SBMA), N-vinylpyrrolidone (NVP), and zinc sulfate heptahydrate (ZnSO₄·7H₂O) for growing the hydrogel layer by ultraviolet initiation. The hydrogel coating demonstrated tough adhesion performance to the catheter, and the interfacial bonding strength achieved 536 N/m. Meanwhile, the hydrogel coating had a variable thickness adjusted by QCS and possessed excellent hydrophilicity (WCA = 24.6°) and low surface friction properties (COF = 0.0357) based on the formation of the hydration layer. Furthermore, the introduction of ZnSO₄·7H₂O endowed the hydrogel coating with prominent antimicrobial properties against Escherichia coli (Gram-negative bacteria) and Bacillus subtilis (Gram-positive bacteria). This approach paves an avenue for fabricating hydrogel coatings with strong interface stability, controllable thickness, lubrication, and antibacterial properties.

Chiral spirocyclic oxetanes [2-oxo-spiro(3H-indole-3,2′-oxetanes)] were subjected to irradiation in the presence of a chiral thioxanthone catalyst (5 mol %) at λ = 398 nm. An efficient kinetic resolution was observed, which led to an enrichment of one oxetane enantiomer as the major enantiomer (15 examples, 37−50% yield, 93−99% ee). The minor enantiomer underwent decomposition, and the decomposition products were carefully analyzed. They arise from a photocycloreversion (retro-Paternò–Büchi reaction) into a carbonyl component and an olefin. The cycloreversion offers two cleavage pathways depending on whether a C−O bond scission or a C−C bond scission occurs at the spirocyclic carbon atom. The course of this reaction was elucidated by a suite of mechanistic, spectroscopic, and quantum chemical methods. In the absence of a catalyst, cleavage occurs exclusively by initial C−O bond scission, leading to formaldehyde and a tetrasubstituted olefin as cleavage products. Time-resolved spectroscopy on the femtosecond/picosecond time scale, synthetic experiments, and calculations suggest the reaction to occur from the first excited singlet state (S₁). In the presence of a sensitizer, triplet states are populated, and the first excited triplet state (T₁) is responsible for cleavage into an isatin and a 1,1-diarylethene by an initial C−C bond scission. The kinetic resolution is explained by the chiral catalyst recruiting predominantly one enantiomer of the spirocyclic oxindole. A two-point hydrogen-bonding interaction is responsible for the recognition of this enantiomer, as corroborated by NMR titration studies and quantum chemical calculations. Transient absorption studies on the nanosecond/microsecond time scale allowed for observing the quenching of the catalyst triplet by either one of the two oxetane enantiomers with a slight preference for the minor enantiomer. In a competing situation with both enantiomers present, energy transfer to the major enantiomer is suppressed initially by the better-binding minor enantiomer and─as the reaction progresses─by oxindole fragmentation products blocking the binding site of the catalyst.

Dynamic organic phosphorescent materials present great potential for practical applications. But the temperature-sensitive nature of organic phosphors makes the development of high-temperature dynamic organic phosphorescence (HTDOP) a significant challenge. Herein, we report a HTDOP system assembled from β-cyclodextrins (β-CDs) and 4-diphenylamino-benzoic acid (TPAC). The TPAC@β-CDs complex system exhibits only short-lived fluorescence at room temperature but transitions to phosphorescence emission with an ultralong emission lifetime of up to 567 ± 13 ms upon heating. A mechanistic study combining spectroscopic analysis, ¹H NMR, and Fourier Transform Infrared Spectroscopy revealed that the intermolecular hydrogen bonding interactions effectively suppressed nonradiative relaxation of triplets even at temperature as high as 140 °C. Meanwhile, elevated temperatures also drive oxygen out of the system, significantly reducing quenching processes and ensuring the robust survival of HTDOP. Additionally, the introduction of fluorescent dyes permits color regulation of the afterglow from green to red through Förster resonance energy transfer from the triplet to the singlet state. Moreover, this system’s fast and reliable response upon high temperature makes it an excellent candidate for overtemperature trace detection in electronic components and circuit diagnostics. This work discloses an effective strategy for constructing HTDOP systems that can be fully exploited in a range of fields.

The shift toward a circular economy has increased efforts to derive valuable chemicals from renewable resources, including chitin-rich waste. Mushroom cultivation generates significant waste, particularly the stalks left behind on breeding beds, which contain a substantial amount of chitin with untapped potential. This research establishes a proof of concept for valorizing this waste stream by converting it into valuable chitin oligosaccharides, which have applications across food, feed, agriculture, and pharmaceuticals. Using a combined approach of enzymatic saccharification with five chitinolytic enzymes, followed by precision fermentation of the resulting N-acetyl-d-glucosamine (GlcNAc), we successfully produced defined chitinpentaose. Chitin extracted from Agaricus bisporus brown demonstrated the highest saccharification efficiency, achieving a GlcNAc conversion of 31 ± 1% (w/w). Our findings highlight the necessity of purifying the saccharification product to ensure product specificity during fermentation, although the production strain’s growth remained suboptimal compared to commercially available GlcNAc. Using an engineered E. coli strain, we achieved pure chitinpentaose, with a yield of 0.0327 g/L at a 10 mL scale and production levels (g/OD₆₀₀) comparable to those obtained with HPLC-grade commercial GlcNAc. This study provides a foundation for further research aimed at improving biocatalyst recycling and optimizing the growth phase, thereby enhancing the cost-efficiency and scalability of this sustainable bioconversion process.

In this work, we present two alternative computational strategies to determine the populations of nonbonded aggregates. One approach extracts these populations from molecular dynamics (MD) simulations, while the other employs quantum mechanical partition functions for the most relevant minima of the multimolecular potential energy surfaces (PESs), identified by automated conformational sampling. In both cases, we adopt a common graph-theory-based framework, introduced in this work, for identifying aggregate conformations, which enables a consistent comparative assessment of both methodologies and provides insight into the underlying approximations. We apply both strategies to investigate phenol aggregates, up to the tetramer, at different concentrations in phenol/carbon tetrachloride mixtures. Subsequently, we simulate the concentration-dependent OH stretching IR region by averaging the harmonic Infrared (IR) spectra of aggregates using the populations predicted by each strategy. Our results indicate that the populations extracted from MD trajectories yield OH stretching signals that closely follow the experimental trends, outperforming the spectra from populations obtained by systematic conformational searches. Such a better performance of MD is attributed to a better description of the entropic contributions. Moreover, the proposed protocol not only successfully addresses a very challenging problem but also offers a benchmark to assess the accuracy of the intermolecular force fields.