Chinese Chemical Letters最新文献

A facile visible-light-induced 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) catalyzed four-component reaction of alkenes, quinoxalin-2(1H)-ones, P₄S₁₀ and alcohols has been developed at room temperature. This tandem reaction provides an efficient strategy for the construction of various phosphorodithioate-containing quinoxalin-2(1H)-ones with moderate to good yields by using air (dioxygen) as the green oxidant. Experimental studies revealed a radical process was involved in this photochemical reaction.

Acidification of paper-based relics is a common problem, leading to their degradation and eventual loss. Paper deacidification is highly dependent on a limited variety of alkaline materials, and the development of new materials that are safe, efficient and easy-to-prepare is highly demanded to ensure a high level of safety and effective protection of paper-based relic. This study proposes the introduction of layered double hydroxide (LDH) and its calcined product, mixed metal oxide (layered double oxide (LDO)), as innovative protective materials for the deacidification of paper with varying levels of acidity. The results demonstrate that treatment with Mg-Al LDH/LDO can effectively modify the pH of acidic paper (e.g., pH ∼ 4.0–6.4) to a neutral or weakly basic state, maintaining this desirable pH range even under long-term accelerated aging condition. Remarkably, LDH proves to be well-suited for the protection of slightly acidified paper (e.g., pH > 5.5), while LDO serves as an especially option for the deacidification of severely acidified paper (e.g., pH ≤ 5.5). During aqueous deacidification, due to the memory effect of the LDH-based materials, LDO is converted to rehydrated LDH, which creates a mild and appropriate alkaline retention in the paper, avoiding damage caused by strong alkalinity such as cellulose degradation and pigment fading during subsequent long-term natural preservation of the paper. Furthermore, Mg-Al LDH/LDO materials also exhibit flame-retardant and bacteriostatic properties. This opens up opportunities for the safe, efficient and multifunctional protection of acidified paper-based relics.

Photocatalytic hydrogen peroxide (H₂O₂) synthesis, driven by solar energy, offers a sustainable and cleaner alternative for producing green H₂O₂ from water and oxygen. 2D photocatalysts have emerged as powerful materials for this purpose due to their unique physiochemical properties such as a flexible planar structure and large surface area. This review provides a comprehensive overview of the latest advances in 2D photocatalytic materials employed in H₂O₂ synthesis, including metal oxides, metal chalcogenides, bismuth-based materials, graphitic carbon nitrides (g-C₃N₄), metal−organic frameworks (MOFs), and covalent organic frameworks (COFs). Beginning with an extensive introduction to possible reaction routes for photocatalytic H₂O₂ synthesis, we summarize the common methods for H₂O₂ detection, crucial for obtaining reliable results in H₂O₂ studies. Additionally, we highlight molecular-level modification strategies for 2D photocatalysts, such as surface modification, ion doping, defect engineering, and heterojunction construction, which promote high-efficiency solar-to-chemical conversion for sustainable H₂O₂ photosynthesis. Furthermore, we discuss key issues and provide perspective outlooks for the efficient and sustainable generation of H₂O₂ in scale-up industrial production. This review offers in-depth insights into different reaction pathways of H₂O₂ synthesis and provides design principles for 2D photocatalysts to enhance H₂O₂ production, guiding the development of efficient photocatalysts for H₂O₂ synthesis.

As a key biomarker for noninvasive diagnosis of diabetes, the selective detection of trace acetone in exhaled gas using a portable and low-cost device remains a great challenge. Semiconductor metal oxide (SMO) based gas sensors have drawn signification attention due to their potential in miniaturization, user-friendliness, high cost-effectiveness and selective real-time detection for noninvasive clinical diagnosis. Herein, we propose a one-pot solvent evaporation induced tricomponent co-assembly strategy to design a novel ordered mesoporous SMO of silica-implanted WO₃ (SiO₂/WO₃) as sensing materials for trace acetone detection. The controlled co-assembly of silicon and tungsten precursors and amphiphilic diblock copolymer poly(ethylene oxide)-block-polystyrene (PEO-b-PS), and the subsequent thermal treatment enable the local lattice disorder of WO₃ induced by the amorphous silica and the formation of ordered mesoporous SiO₂/WO₃ hybrid walls with a unique metastable ε-phase WO₃ framework. The obtained mesoporous SiO₂/WO₃ composites possess highly crystalline framework with large uniform pore size (12.0–13.3 nm), high surface area (99–113 m²/g) and pore volume (0.17–0.23 cm³/g). Typically, the as-fabricated gas sensor based on mesoporous 2.5 %SiO₂/WO₃ exhibits rapid response/recovery rate (5/17 s), superior sensitivity (R_air/R_gas = 105 for 50 ppm acetone), as well as high selectivity towards acetone. The limit of detection is as low as 0.25 ppm, which is considerably lower than the thresh value of acetone concentration (>1.1 ppm) in the exhaled breath of diabetic patients, demonstrating its great prospect in real-time monitoring in diabetes diagnosis. Moreover, the mesoporous 2.5 %SiO₂/WO₃ sensor is integrated into a wireless sensing module connected to a smart phone, providing a convenient real-time detection of acetone.

The carboxylation of readily available organo halides with CO₂ represents a practical strategy to afford valuable carboxylic acids. However, efficient carboxylation of inexpensive unactivated alkyl chlorides is still underdeveloped. Herein, we report the electro-reductive carboxylation of CCl bonds in unactivated chlorides and polyvinyl chloride with CO₂. A variety of alkyl carboxylic acids are obtained in moderate to good yields under mild conditions with high chemoselectivity. Importantly, the utility of this electro-reductive carboxylation is demonstrated with great potential in polyvinyl chloride (PVC) upgrading, which could convert discarded PVC from hydrophobic to hydrophilic functional products. Mechanistic experiments support the successive single electron reduction of unactivated chlorides to generate alkyl anion species and following nucleophilic attack on CO₂ to give desired products.