RSC Advances最新文献

This paper introduces a novel optical cell design that integrates ultraviolet-visible (UV-vis) and laser-induced breakdown spectroscopy (LIBS) for comprehensive vapor phase chemical analysis at temperatures up to 450 °C. The motivation behind this research is to overcome the limitations of existing vapor phase spectroscopy techniques by providing a versatile and efficient solution for detailed chemical analysis in high-temperature environments. The modular design of the optical cell enables the optimization of optical path length and beam diameter to meet the specific requirements of each spectroscopy technique. Experimental results demonstrated good resolution when analyzing both organic (naphthalene) and inorganic (SbCl₅) vapors. A key innovation discussed is the implementation of a cover gas buffer to prevent material buildup on the optical windows, ensuring the integrity and longevity of the cell during extended operation. This approach enhances the capabilities of existing techniques and extends their applicability to various scientific and industrial applications, including environmental monitoring, pharmaceuticals, materials science, and chemical manufacturing.

Co and Ni complexes having the 6,6′-dihydroxy-2,2′-bipyridine (DHBP) ligand [CoCl₂(dhbp), NiBr₂(dhbp)] in the presence of organoaluminum cocatalysts showed much higher catalytic activity in 1,3-butadiene polymerization than the complexes having the 2,2′-bipyridine or 6,6′-dimethoxy-2,2′-bipyridine ligand without hydroxy groups. The polybutadienes obtained had 1,4-cis structure (up to 94.6%). In contrast, addition of 5-norbornene-2-methyl amine in 1,3-butadiene polymerization catalyzed by NiBr₂(dhbp)/methylaluminoxane (MAO) caused a marked change in the microstructure of the polybutadiene to the iso-1,2-structure with high chemo- and stereoselectivities (mm > 99%).

Terpenoids, a heterogeneous group of natural products, have garnered considerable attention in the field of drug discovery. This is attributed to their vast diversity, intricate structural features, and extensive biological activities. Tripterygium wilfordii Hook. f., a traditional medicinal plant with widespread application in East Asia, is particularly enriched in terpenoids, which can be classified into sesquiterpenoids, diterpenoids, and triterpenoids. The present review provides a comprehensive elaboration of the chemical structures and biological activities of 217 terpenoids isolated from T. wilfordii. The purpose is to shed light on their potential in pharmacological research and to stimulate innovative drug discovery as well as clinical applications. These terpenoids display a broad spectrum of biological activities, such as antitumor, anti – inflammatory, immunosuppressive, and other therapeutic effects. Nevertheless, their clinical application is impeded by issues related to toxicity and poor bioavailability. Future research efforts should be concentrated on exploring effective strategies to alleviate toxicity and enhance drug delivery systems. In addition, in – depth investigation into the structure–activity relationships and the identification of new active constituents are crucial for the development of more potent and safer drugs. This review serves as an exhaustive reference for the discovery and development of novel drugs based on the natural active products of T. wilfordii, providing valuable insights and guidance for researchers in the relevant field.

Radio frequency identification (RFID) technology has made significant strides in recent years, opening up a world of possibilities for various industries. However, to achieve success, reliable and accurate real-time data is crucial. One exciting application of RFID technology is fast and wireless detection of gases. Hydrogen, in particular, is considered a clean fuel. However, it is highly flammable, and detecting it quickly and accurately is challenging in various industries. In this regard, our research focuses on developing a high-conductivity graphite paste for RFID tags integrated with a wireless hydrogen sensor based on nano-CeO₂–Fe₂O₃–graphene oxide. In this work, we obtained a graphite paste using Ultra High Power (UHP) graphite electrodes with a high conductivity of 4.75 × 10⁵ S cm⁻¹ for non-metallic substrates and 4 × 10⁶ S cm⁻¹ with aluminum substrate. Furthermore, we incorporated a hydrogen gas detection sensor into the RFID tag utilizing graphene oxide and cerium oxide–iron oxide nanoparticles. The sensor demonstrated high sensitivity to low concentrations of H₂ gas (1 ppm), with stable and repeatable performance. The wireless sensing response was evaluated through reflection coefficient (S₁₁) measurements, confirming effective impedance matching between the RFID chip and antenna. Through this research, we aim to promote the advancement of RFID technology by introducing a low-cost, battery-free sensing platform using graphite and nano-engineered materials, suitable for diverse industrial applications.

Energetic plasticizers are used to improve the mechanical properties of advanced energetic formulations while increasing the overall energy content. Although nitro-1,2,5-oxadiazoles (nitrofurazans) possess excellent energetic properties such as a favorable oxygen balance and high heat of formation, their use as plasticizers has received little attention in the scientific literature. Four nitrofurazanyl ethers were synthesized by substitution of dinitrofurazan with linear alkoxides. The synthesized compounds were extensively analyzed by Fourier-transform infrared (FT-IR) spectroscopy, Raman spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), electrospray ionization (ESI) mass spectroscopy, mechanical sensitivity test, ¹H nuclear magnetic resonance (NMR) spectroscopy and ¹³C NMR spectroscopy. They have lower mechanical sensitivity (>40 J) compared to modern energetic plasticizers in use, including 2,2-dinitropropyl formal/acetal (BDNPA/F), n-butylnitratoethylnitramine (BuNENA), and dinitrodiazaalkane (DNDA-57). In addition, the most promising compound 3-(2-(2-(2-azidoethoxy)ethoxy)ethoxy)-4-nitro-1,2,5-oxadiazole (NFPEG3N3) exhibits competitive thermal properties, with a lower glass transition temperature of −72 °C compared to BNDPA/F (−67 °C) and a higher thermal decomposition temperature of 179 °C compared to BuNENA (173 °C). The enthalpy of formation and heat of explosion of NFPEG3N3 were calculated to be −41.7 kJ mol⁻¹ and 3421 J g⁻¹, respectively. The impact of NFPEG3N3 on the glass transition temperature, viscosity and decomposition of the energetic binder glycidyl azide polymer (GAP)-diol was investigated and showed a remarkable decrease in viscosity (45.4%) and glass transition temperature (−3.3 °C) when compared to benchmark plasticizers in 10 wt% mixtures. These results demonstrate the potential of NFPEG3N3 as an insensitive and highly energetic plasticizer.

To extend the applications of phase-change materials to multiple scenarios, Fe₃O₄ nanoparticles were deposited on the surface of mica with a layer-like structure using a simple method, and composite phase-change materials (CPCMs) with dual-driven energy conversion performance were subsequently obtained via vacuum impregnation. The addition of boron nitride (BN) and cellulose nanofibers (CNFs) endowed the CPCMs with higher thermal conductivity (0.85 W m⁻¹ K⁻¹) and lower specific heat capacity (1.42 MJ m⁻² K⁻¹), thereby constructing an effective heat transfer channel. The photothermal conversion efficiency of the CPCMs reached up to 88.36%. The magnetic Fe₃O₄ nanoparticles endowed the CPCMs with magnetic responsiveness, enabling the phase transition process to complete within just 112 s under a magnetic field. With a high phase-change material loading (82.65%), the CPCMs maintained excellent thermal stability during the energy conversion process. These results provide guidance for the preparation of CPCMs with multiple types of efficient energy conversion.

Among quinoline-fused heterocycles, tricyclic pyrimidoquinoline nuclei have received considerable attention from synthetic chemists and medicinal and materials scientists over many years because they occur commonly in various biologically important natural products and potent drugs that exhibit anticancer, antibacterial, anti-inflammatory, antilipidemic, antioxidant and antimalarial activities. This study will be beneficial for medicinal chemists in the field of drug discovery to synthesize new fused tricyclic pyrimidoquinolines as potent therapeutic agents. This review provides a comprehensive compilation of the methodologies developed for the synthesis of all six known types of pyrimidoquinolines reported thus far. This article includes synthesis via solvent-free reactions, Vilsmeier–Haack reaction, Lewis and Brønsted acid catalysis, Pictet–Spengler reaction, the use of metal oxide nanoparticles as a green catalyst, multicomponent reactions (MCR), the use of L-proline as an environmentally friendly organocatalyst, aza-Wittig reaction, the use of β-cyclodextrin (β-CD) as a supramolecular catalyst, ultrasound irradiation, microwave-assisted reaction and ultraviolet light (UV₃₆₅) irradiation. To the best of our knowledge, this is the first review that focuses on the synthesis of all six types of pyrimidoquinolines along with mechanistic aspects. Some medicinal applications are also mentioned.

Li metal is known as the most ideal anode material for Li-ion batteries due to its high theoretical capacity (3860 mA h g⁻¹) and low redox potential (−3.04 V vs. SHE). However, the dendrite growth and volume expansion caused by inhomogeneous and loose Li deposition limit the practical application of Li metal anode. Herein, oxidized carbon cloth (OCC) modified with oxygen-containing functional groups (–COOH, –C–OH, CO) is prepared by oxidation in a water bath environment. The polar oxygen-containing functional groups enhance the adsorption capacity of Li⁺, reduce the nucleation barrier, and effectively regulate the uniform distribution of Li⁺ on carbon fiber. Meanwhile, the large specific surface area of carbon fiber can reduce the local current density and inhibit dendrite formation. The sufficient internal space of the OCC can store the deposited Li, effectively easing the volume expansion. As such, the OCC‖Li half-cells exhibit a high coulombic efficiency (98.2%) after 250 cycles at 1 mA cm⁻². Besides, the OCC‖LiFePO₄ full cell capacity is 117 mA h g⁻¹ after 300 cycles at 1C. The experimental results show that the OCC prepared by a simple and efficient oxidation method plays a positive role in exploring high energy density Li metal batteries.

Magnesium hydroxide (MH) is widely recognized as an environmentally friendly, halogen-free flame retardant and has been extensively applied in ethylene-vinyl acetate (EVA) copolymers. However, its poor dispersion in the polymer matrix and low flame retardant efficiency remain significant challenges. In this study, hexagonal magnesium hydroxide (MHz) with well-defined morphology, high specific surface area, and excellent dispersion was inventively synthesized via hydrothermal synthesis using sodium hydroxide (NaOH) and sodium carbonate (Na₂CO₃) as the hydrothermal medium. Three EVA composites filled with MHz and two different commercial magnesium hydroxides (MHx and MHy) were prepared via melt-blending, and their flame retardant and mechanical properties were systematically compared. The results indicate that the EVA composite containing 60 wt% MHz (EVA/MHz60) exhibits superior flame retardant performance, achieving a limiting oxygen index (LOI) of 49.2%, which is 53.8% and 9.1% higher than that of MHx and MHy, respectively. The UL-94 rating reached V-0. Furthermore, the peak heat release rate (PHRR) of EVA/MHz60 is significantly reduced to 150.6 kW m⁻², marking a 33.2% and 29.9% reduction compared to the EVA composite containing 60 wt% MHx (EVA/MHx60) and EVA composite containing 60 wt% MHy (EVA/MHy60), respectively. Additionally, the tensile strength of EVA/MHz60 is improved by 101.6% and 76.4% compared to that of EVA/MHx60 and EVA/MHy60, respectively. The improvement in tensile strength of the EVA/MHz60 composite can be attributed to the nanoscale and uniform dispersion of MHz with hexagonal morphology, which can enhance the interfacial adhesion with the EVA matrix, thus the flame retardant and mechanical properties of the composite can be improved simultaneously.

Removing carbon dioxide from the atmosphere is an attractive way to mitigate the greenhouse gas effect that contributes to climate change. A series of donor-pi (D-π), acceptor-pi (A-π), and π Re(I) pyridyl imidazole complexes have been synthesized and examined under photocatalytic conditions for the photocatalytic reduction of CO₂. The catalytic activity of the complexes was further supported by cyclic voltammetry through the presence of a catalytic current under CO₂ atmosphere. The D-π, π, and A-π complexes were studied to elucidate the effects of incorporating conjugated electron donating vs. withdrawing groups on the catalytic rates and product selectivity. The synthesized complexes were compared with Re(bpy)(CO)₃Br (where bpy is 2,2′-bipyridine), the benchmark catalyst for this transformation. Remarkably, the complex with A-π pendant (RC4) outperformed the π (RC2–3) and D-π (RC5) complexes for the production of formic acid (HCO₂H) in the presence of photosensitizer [Ru(bpy)₃]²⁺ and sacrificial electron donor BIH (1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]-imidazoline). Among the investigated catalysts, RC4 with the A-π pendant showed the highest turnover number (TON) value of 844 for HCO₂H production with 86% carbon selectivity. In stark contrast to the imidazole-pyridine based catalysts reported here that favor formic acid as a product, Re(bpy)(CO)₃Br generated no formic acid under the same conditions. The imidazole-pyridine complexes also function as catalysts for CO₂ reduction without an added photosensitizer, however, the TON values under self-sensitized conditions are poor.