The Royal Society of Chemistry最新文献

Homojunction engineering holds promise for creating high-performance photocatalysts, yet significant challenges persist in establishing and modulating an effective junction interface. To tackle this, we designed and constructed a novel Janus homojunction photocatalyst by integrating two different forms of triazole-based carbon nitride (C₃N₅). In this design, super-sized, ultrathin nanosheets of carbon-rich C₃N₅ grow epitaxially on a nitrogen-rich honeycomb network of C₃N₅, creating a tightly bound and extensive interfacial contact area. This arrangement enhances the built-in internal electric field (IEF) between the two forms of C₃N₅, facilitating faster directional transfer of photogenerated electrons and improved visible-light harvesting. Consequently, Janus-C₃N₅ achieves a remarkable H₂ evolution rate of 1712.4 μmol h^-1 g^-1 under simulated sunlight, which is approximately 5.58 times higher than that of bulk C₃N₅ (306.8 μmol h^-1 g^-1) and 14.1 times higher than another form of bulk C₃N₅ (121.2 μmol h^-1 g^-1). This work offers a new approach to design efficient homojunction-based photocatalysts.

Dynamic covalent bonding (DCB) has been a rising concept for the past several years in materials sciences. This article describes how the bond lability involved in DCB is applied to develop drugs against tropical parasitic diseases such as malaria and bilharziasis. Recently, we showed that some alkoxyamines (typical molecules exhibiting DCB) exhibit in vitro activities against S. mansoni (for A8L, 100% worm mortality in 48 hours at 10 μg ml^-1) and P. falciparum (for A8L, IC₅₀ = 270 nM). Here, the combination of enzymatic-physical (solvent effect) activation or of enzymatic-chemical (acetal hydrolysis) activation is used to develop alkoxyamines that show activity against both parasites. The enzymatic step controls the specificity of the drug.

The development of multi-cation perovskite quantum dots (PQDs) is limited by the low availability of fitting A-site cations due to the unsuitable radii of a large gamut of amine cations. The impact of oversized or undersized cations on the perovskite structure is detrimental to the structural stabilization and electroluminescence efficiency of the PQDs. Researchers are actively seeking suitable-sized cations to mitigate perovskite defect formation and optimize charge carrier confinement within the PQDs. In contrast to cesium (Cs) or formamidine (FA), which are exposed to degradation pathways, guanidinium (GA)-doping has been to provide a suitable radius and the lack a dipole moment. The triple nitrogen functionality of GA enables it to passivate both the PbBr₆ octahedra and surface defects through vacant A-sites and entropically stabilize the perovskite. Furthermore, the insertion of GA into the PQD lattice is enthalpically facilitated by the presence and arrangement of smaller Cs and Br atoms. Herein, we have synthesized a Cs-FA PQD reference into which GA is doped via two chemical routes. Our triple-cation system exhibits substantially improved optical properties and was applied for the fabrication of a PeLED device. The optimized triple-cation PQDs-based PeLED device exhibited an external quantum efficiency of 5.87% and a luminescence of 13726 cd m^-2.

The transformation of renewable feedstocks into aromatic chemicals holds immense potential for advancing a green, low-carbon economy and fostering sustainable development. Herein, we present a novel approach for the conversion of isoeugenol, a renewable lignin derivative, into the valuable flavoring agent vanillin, utilizing ozone as an environmentally benign oxidant. The process optimization was significantly enhanced by the integration of in situ Attenuated Total Reflectance Infrared (ATR-IR) monitoring. The introduction of H₂O not only accelerated the decay of carbonyl oxides (Criegee intermediates) but also mitigated safety hazards stemming from the vigorous decomposition and heat release of secondary ozonides. Compared to the conventional Thin Layer Chromatography (TLC) method, ATR-IR monitoring demonstrated superior sensitivity and precision in determining the reaction endpoint, leading to a remarkable vanillin yield of 96.86% upon complete conversion of isoeugenol. Additionally, a comparative assessment of the sustainability of our approach with existing methods was undertaken, and valuable recommendations for safety assessments were provided to ensure the inherent safety of chemical engineering reactions. The present study serves as a pioneering effort in facilitating the implementation of a scalable, economically feasible and environmentally sustainable strategy for biomass flavor production, while contributing to the broader adoption of in situ spectroscopic technology within the larger economy.

This study presents a highly efficient method for 4-aminoquinoline derivative preparation under transition metal-free conditions. The process involves an aerobic oxidative dehydrative coupling of 2,3-dihydroquinolin-4(1H)-ones with various amines, including ammonia, resulting in high yields of the desired products. The method is also applicable to substituted 4-aminoquinoline derivative construction through a cyclization/dehydrative coupling cascade process starting from 2'-amino chalcones. Mechanistic studies reveal that iodine (I₂) is consumed to produce 3-iodoquinolin-4-ol, which acts as a true catalyst with high catalytic efficacy (as low as 0.5 mol%). The presence of halogen bonding is critical in the inter-molecular transfer hydrogenation process to generate inactive quinolin-4-ol. Subsequently, using air/oxygen as the terminal oxidant, the iodine anion was oxidized to I₂ to regenerate the 3-iodoquinolin-4-ol from quinolin-4-ol in the catalytic cycle. Key benefits of this methodology include its simplicity, transition metal-free conditions, environmentally-benign oxidant, and high atom economy, making it a valuable approach for synthesizing medicinally significant 4-aminoquinoline derivatives.

Recently published in vivo observations have highlighted the presence of cruciform structures within the genome, suggesting their potential significance in the rapid recognition of the target sequence for transcription factor binding. In this in vitro study, we investigate the organization and stability of the sense (coding) strand within the Serum Response Element of the c-Fos gene promoter (c-Fos SRE), specifically focusing on segments spanning 12 to 36 nucleotides, centered around the CArG-box. Through a thorough examination of UV absorption patterns with varying temperatures, we identified the emergence of a remarkably stable structure, which we conclusively characterized as a hairpin using complementary ¹H NMR experiments. Our research decisively ruled out the formation of homoduplexes, as confirmed by supplementary fluorescence experiments. Utilizing molecular dynamics simulations with atomic distance constraints derived from NMR data, we explored the structural intricacies of the compact hairpin. Notably, the loop consisting of the six-membered A/T sequence demonstrated substantial stabilization through extensive stacking, non-canonical inter-base hydrogen bonding, and hydrophobic clustering of thymine methyl groups. These findings suggest the potential of the c-Fos SRE to adopt a cruciform structure (consisting of two opposing hairpins), potentially providing a topological recognition site for the SRF transcription factor under cellular conditions. Our results should inspire further biochemical and in vivo studies to explore the functional implications of these non-canonical DNA structures.

The nitrogen-bridgehead is a common structural motif present in a multitude of natural products. As many of these abundant compounds exhibit biological activities, e.g. against cancer or bacteria, these derivatives are of high interest. While natural products are often associated with problematic characteristics, such as elaborate separation processes, high molecular complexity and limited room for derivatization, purely synthetic approaches can overcome these challenges. Many synthetic procedures have been reported for preparation of artificial nitrogen bridgehead compounds, however, to our surprise only a fraction of these has been tested for their bioactivity. This review is therefore meant to give an overview of existing synthetic methods that provide scaffolds containing bridgehead nitrogen atoms, covering the period from 2000 to 2023. Reviews which cover subunits of this topic are referenced as well.

Diverse betulinic acid–dithiocarbamate conjugates were designed and synthesized via a two-step reaction at room temperature. Among the fourteen dithiocarbamate analogs of betulinic acid, DTC2 demonstrated the best antifungal activity against Candida albicans, with a minimum inhibitory concentration (MIC) of 4 μg mL⁻¹, achieving 99% fungicidal activity at the same concentration. These compounds were found to be ineffective against common Gram-negative and Gram-positive pathogens, suggesting their specificity to fungi. Furthermore, DTC2 exhibited synergistic effects with the antifungal drugs fluconazole and nystatin, resulting in a significant decrease in MIC by 64 and 16 folds, respectively, when co-administered. Notably, the molecule also hindered hyphae formation in Candida albicans, thereby reducing its pathogenicity. Furthermore, it displayed time- and concentration-dependent kill kinetics, sterilizing C. albicans within 8 hours at 8× MIC. Additionally, DTC2 exhibits greater efficacy against β-carbonic anhydrase with better docking scores and binding patterns than ethoxyzolamide, a well-known inhibitor of β-carbonic anhydrase.

Both the B-S and S-S bonds of 1,2,4,3,5-trithiadiborolane 1 could be cleaved by potassium graphite (KC₈) to give the first isolable boryl dithiolate DmpB(SK)₂3, whereas the reduction of 1,2,4-triselena-3,5-diborolane 2 with KC₈ afforded the boryl diselenolate DmpB(SeK)(SeSeK) 4, showcasing the unprecedented structural authentication of ligand substituted diselenolate.

Active particles are self-propelling in nature due to the generation of a fore-aft asymmetry in the concentration of solutes around their surface. Both the surface activity and mobility play an important role in the particle dynamics. The solutes are the products of the chemical reaction between the active particle surface and suspending medium. Unlike Janus particles, isotropic active particles have been shown to undergo spontaneous self-propulsion beyond a critical particle size (or the Péclet number). Compared to Janus active particles, there is a third ingredient, namely, advection-induced instability that dictates the dynamics of such particles. The present study numerically investigates the role played by shear rate-dependent viscosity of a suspending medium in the self-phoretic dynamics of such isotropic active particles. Towards this, a non-Newtonian Carreau fluid is taken as the suspending medium. One of the important findings of this study is the presence of a second critical Péclet number beyond which the spontaneous motion of the particle ceases to exist. Even though this critical Péclet number had been previously investigated for Newtonian fluids, strong dependence of the former on the rheology of the suspending medium was not explored. The analysis also shows that a shear thinning fluid significantly reduces the maximum velocity of the particle. In addition, confinement is found to have a significant effect on the axial propulsive velocity of the particle suspended in a Carreau fluid.