Latest ArticlesAxially chiral binaphthol have achieved great success in asymmetric catalysis. Compared to α-binaphthol, axially chiral aryl-β-naphthol are far less reported. Here, we report a method of asymmetric catalysis to construct β-naphthol with up to 99% yield, 95.5:4.5 enantiomeric ratio, using alkynyl esters as precursors and chiral phosphonic acid (CPA)/Lewis acid as catalysts. Key steps involve oxygen transfer and de novo arene formation to set up the chiral axis. Moreover, this methodology provides a versatile platform for structurally divergent synthesis of atroposelective β-naphthol analogs, which are widely found in bioactive molecules and asymmetric catalysts.
A supramolecular assembly composed of perylene diimide derivative (PDI-nm) and nor-seco-cucurbit[10]uril (ns-Q[10]) was designed. The excellent host-guest interaction between PDI-nm and ns-Q[10] prevented the aggregation-caused quenching (ACQ) effect of PDI-nm, resulting in a luminescent assembly. The addition of spermine to the PDI-nm/ns-Q[10] assembly restored the ACQ of PDI-nm due to the competitive binding of spermine to ns-Q[10], which released PDI-nm. The assembly based on this principle showed ultra-high sensitivity for the detection of spermine with a detection limit as low as 7.84 × 10−7 mol/L in aqueous solution and 3.69 × 10−7 mol/L in plasma solution. Moreover, an artificial light-harvesting system based on this assembly was proposed, benefiting from its good luminescent performance. Nile red (NiR) functioned as an acceptor loaded into assembly, and a highly efficient energy transfer process occurred from PDI-nm/ns-Q[10] to NiR, with an efficiency up to 87%.
Triflumezopyrim (TFM) is a novel mesoionic pyrido[1,2-α]pyrimidinones insecticide, which acts on nicotinic acetylcholine receptors (nAChRs) and has no cross-resistance with other insecticides. Herein, we firstly developed a new continuous flow approach to synthesis 2-[3-(trifluoromethyl)phenyl]malonic acid, a key intermate of TFM, coupling with esterification, condensation, and hydrolysis. All three-step reactions were optimized and transformed into a continuous synthesis mode by three micro reaction units. Compared with the batch mode, the total reaction time and overall separation yield were improved from more than 12 h and 60% to 18 min and 73.38%, respectively. The solvent consumption and waste emission were significantly reduced, which also provides an eco-friendly and efficient potential tool for the development and production of mesoionic pyrido[1,2-α]pyrimidinones insecticide.
The preparation, functionalization, and investigations in host-guest properties of high-level pillararene macrocycles have long been a big challenge because of the lack of efficient synthetic methods. Herein, a novel type of pillararene derivative, namely desymmetrized pillar[8]arene (DP[8]A), has been successfully synthesized via a facile two-step strategy with high yield. Compared with its pillar[8]arene counterpart, DP[8]A is composed of four alkoxy-substituted benzene units and four bare benzene rings. Single crystal analysis has been performed in order to unveil the molecular conformation and packing mode of DP[8]A, which indicated that DP[8]A possesses a unique chair-like structure and much smaller steric hindrance. Density functional theory (DFT) calculations and electrostatic potential map suggested the inhomogeneous electronic distribution in the DP[8]A cavity. Water-soluble carboxylate-modified DP[8]A, that is, CDP[8]A, was also prepared to investigate the host-guest properties in aqueous solution with methyl viologen (MV), where the binding constant and morphologies of the formed host-guest complexes have been studied. In all, this new version of eight-membered pillararene derivative might potentially serve as a powerful macrocycle candidate for further applications in supramolecular chemistry.
Despite ongoing advancements in cancer treatment, the emergence of primary and acquired resistance poses a significant challenge for both traditional chemotherapy and immune checkpoint blockade therapies. The demand for targeted therapeutics for multidrug-resistant cancer is more important than ever. Peptides, as emerging alternatives to current anticancer drugs, offer exquisite versatility in facilitating the design of novel oncology drugs, with the core superiorities of good biocompatibility and a low tendency to induce drug resistance. This review comprehensively introduces the pharmacological mechanisms of peptide-based drugs and strategies for overcoming multidrug resistance (MDR) in cancers, including inducing cell membrane lysis, targeting organelles, activating anticancer immune responses, enhancing drug uptake, targeting ATP-binding cassette (ABC) transporters, and targeting B-cell lymphoma-2 (BCL-2) family proteins. Additionally, the current clinical applications of representative peptides in combating MDR cancers and their potential directions for medicinal chemistry research have been thoroughly discussed. This review offers essential insights into the novel treatment approaches for MDR cancers and highlights the trends and perspectives in this field.
The oxygen reduction reaction (ORR) is a crucial process in Zn-air systems, and the catalyst plays a significant role in this reaction. However, reported catalysts often suffer from poor durability and stability during the ORR process. Herein, we synthesized La-Fe bimetallic nanoparticles encapsulated in a N-doped porous carbon dodecahedron (La-Fe/NC) originated from ZIF-8 by a simple direct carbonization. The La-Fe/NC catalyst had a numerous mesopores and dendritic outer layer generated by carbon nanotubes (CNTs), forming a high conductivity network that helped to optimize electron transfer and mass transport in the ORR process. The effect of different doping transition metals and metal ratios on the ORR activity of Zn-air batteries was investigated. In alkaline media, the La-Fe/NC showed the highest ORR catalytic activity, with a half-wave potential (E1/2) of 0.879 V (vs. RHE, Pt/C 0.845 V). After 5000 cycles, the E1/2 of the La-Fe/NC catalyst only decreased by 7 mV, and its performance in stability tests and methanol tolerance tests was superior to Pt/C. When used as the air electrode in a Zn-air battery, the La-Fe/NC catalyst demonstrated an excellent specific capacity of 755 mAh/g and a peak power density of 179.8 mW/cm2. The results provide important insights for the development of high-performance Zn-air batteries and new directions for the design of ORR catalysts.
Pyrrolobenzoxazines are a rare terpene-amino acid family of natural products with potent biological activities. Here, we reported the full biosynthetic pathway of paeciloxazine (1), a typical pyrrolobenzoxazine, with significant insecticidal activity. Base on heterologous expression, chemical complement experiment, and in vitro biochemical assays, we demonstrated the sesquiterpene portion of 1 derived from discontinuously oxidations of amorphdiene, in which P450 monooxygenase PaxH catalyzed a cascade of hydroxylation and epoxidation, while two flavin dependent monooxygenases are involved in the transformation of the esterified tryptophan into a pyrrolobenzoxazine core. Furthermore, a total of 15 compounds were generated through heterologous expression, of which 13, 17 and 20 showed potential antiepileptic activity. This study fully elucidated the biosynthetic pathway of paeciloxazine (1) and showed the diversity and complexity of constructing natural products by organisms.
The self-assembled nanoparticles (SAN) formed during the decoction process of traditional Chinese medicine (TCM) exhibit non-uniform particle sizes and a tendency for aggregation. Our group found that the pH-driven method can improve the self-assembly phenomenon of Herpetospermum caudigerum Wall., and the SAN exhibited uniform particle size and demonstrated good stability. In this paper, we analyzed the interactions between the main active compound, herpetrione (Her), and its main carrier, Herpetospermum caudigerum Wall. polysaccharide (HCWP), along with their self-assembly mechanisms under different pH values. The binding constants of Her and HCWP increase with rising pH, leading to the formation of Her-HCWP SAN with a smaller particle size, higher zeta potential, and improved thermal stability. While the contributions of hydrogen bonding and electrostatic attraction to the formation of Her-HCWP SAN increase with rising pH, the hydrophobic force consistently plays a dominant role. This study enhances our scientific understanding of the self-assembly phenomenon of TCM improved by pH driven method.
Leveraging the interplay between the metal component and the supporting material represents a cornerstone strategy for augmenting electrocatalytic efficiency, e.g., electrocatalytic CO2 reduction reaction (CO2RR). Herein, we employ freestanding porous carbon fibers (PCNF) as an efficacious and stable support for the uniformly distributed SnO2 nanoparticles (SnO2PCNF), thereby capitalizing on the synergistic support effect that arises from their strong interaction. On one hand, the interaction between the SnO2 nanoparticles and the carbon support optimizes the electronic configuration of the active centers. This interaction leads to a noteworthy shift of the d-band center toward stronger intermediate adsorption energy, consequently lowering the energy barrier associated with CO2 reduction. As a result, the SnO2PCNF realizes a remarkable CO2RR performance with excellent selectivity towards formate (98.1%). On the other hand, the porous carbon fibers enable the uniform and stable dispersion of SnO2 nanoparticles, and this superior porous structure of carbon supports can also facilitate the exposure of the SnO2 nanoparticles on the reaction interface to a great extent. Consequently, adequate contact between active sites, reactants, and electrolytes can significantly increase the metal utilization, eventually bringing forth a remarkable 7.09 A/mg mass activity. This work might provide a useful idea for improving the utilization rate of metals in numerous electrocatalytic reactions.
Selenium is one of the important trace elements in the human body. Its deficiency will directly affect human health. With people's attention to health, the content of selenium in food has gradually attracted attention. However, detecting selenium compounds in complex samples remains a challenge. In this work, we built an online heating-reaction device. This device combines the electrospray extraction ionization mass spectrometry (EESI-MS) with the heating reaction device, which can simultaneously detect various selenium compounds in complex liquid samples. Under acidic conditions, the sample was heated and catalyzed by a heating reaction device, so that the SeO32− and O-phenylenediamine (OPD) could generate 1,3-dihydro-2,1,3-benzoselenadiazole. Based on the above reactions, we can detect organic selenium, inorganic selenium and other compounds in liquid samples by organic mass spectrometry. In this experiment, we determined the content of three forms of selenium: selenomethionine (SeMet), l-selenocystine (SeCys(2)), and sodium selenite. The calibration curves for SeMet, SeCys(2), and sodium selenite showed strong linearity within a range of 0.50–50.00 µg/L. The limits of detection (LOD) for the three compounds were 0.22, 0.27, and 0.41 µg/L, respectively. The limits of quantification (LOQ) were 0.68, 0.81, and 1.23 µg/L, respectively. Spiked recoveries at three levels ranged from 98.8% to 106.1%. In addition, this method can simultaneously detect three selenium compounds and three other specific chemical components in tea infusion samples, providing a rapid and efficient method for identifying tea quality.
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