Ag(I)-Catalyzed/Acid-Mediated Cascade Cyclization of ortho-Alkynylaryl-1,3-dicarbonyls to Access Arylnaphthalenelactones and Furanonaphthol Libraries via Aryl-Disengagement

ortho-Alkynylarylketone derivatives were employed as key precursors for a one-pot synthesis of arylnaphthalenelactone and furanonaphthol libraries. In this work, we discovered a cost-effective protocol to prepare arylnaphthalenelactones in one-pot using inexpensive starting material, malonate ester, which was conveniently functionalized leading to a variety of structures. Moreover, we also found an unexpected oxy-dearylation reaction which could be used to synthesize furanonaphthol analogs. These novel methods could be applied to a broad range of substrates to give the corresponding products in up to 83% yield. Notably, these classes of compounds exhibited more significant inhibition against protein-tyrosine phosphatase 1B (PTP1B) enzyme than a standard compound, ursolic acid.     

Determination of cobalt ion based on polyethyleneimine modified silver nanoclustersEI北大核心CSCD

PolyethyleneiminePEImodified silver nanoclustersAg NCswere synthesized through chemical reduction method by using PEI as stabilizerAgNO3 as silve source and ascorbic acid as reducing agentand it was applied to the detection of cobalt ions. It was found that the fluorescence of the silver nanoclusters was quenched by Co2+ for the aggregation of PEI-Ag NCs caused by the coordination between cobalt ion and amino group on polyethyleneimine. Under the optimized experimental conditionsthe fluorescence quenching degree of PEI-Ag NCs was piecewise linear with the concentration of cobalt ion in the range of 8.30×10-7-4.17×10-4 mol/L and the detection limit was 0.41 μµmol/L. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

An asymmetric N-rim partially substituted calix[4]pyrrole: Its affinity for Ag(I) and its destruction by Hg(II)

A new partially substituted calix[4] pyrrole derivative obtained by the introduction of three thioamide functionalities in the N-rim has been synthesised and fully characterised by ¹H, ¹³C, HSQC, ROESY NMR and mass spectroscopy. Computer modelling suggested an alternate conformation which was confirmed through ROESY ¹H NMR. The receptor interacts only with the silver cation as shown by ¹H NMR. The strength of interaction is quantitatively assessed by titration calorimetry. N-rim modification eliminates the possibility of interaction with anions. Unlike calix[4] pyrrole derivatives obtained by the introduction of functionalities through the meso-position, addition of Hg(NO₃)₂ leads to the degeneration of the receptor as demonstrated by ¹H NMR, FTIR and XPS analyses. This is for the first time reported. Molecular simulation studies show significant strain in the mercury bound ligand in bonds, angles, torsions leading to the destruction of the receptor. Given the negative environmental impact produced by the availability of silver ions in aquatic organisms, the fundamental studies indicate that this receptor offers potential applications for monitoring silver (ion selective electrode) or indeed as a decontaminating material for removing silver ions from water.     

Silver(I) Complexes of Two Flexible Bis-phospholane Ligands: Metallamacrocycles,Polymeric Chains,and Metallacryptands

In a 2:2 reaction with silver(I) chloride or bromide, 1,5-bis(1-phospholano)pentane ( 1a ) afforded frame-like macrocyclic structures, with intra- ( 2 , Cl) or intermolecular ( 3 , Br) halido bridges. In contrast, 1,7-bis(1-phospholano)heptane ( 1b ) formed coordination polymers 4a (Cl) and 4b (Br) with bridging bis-phospholane and halido ligands. A unique paddle wheel-type metallacryptand structure 5 was obtained from 1a and silver(I) bromide in a 2:3 reaction (M:L). All complexes were fully characterized by NMR, IR spectroscopy, mass spectrometry, and X-ray crystallography.     

Biologically and environmentally benign approach for PHB-silver nanocomposite synthesis and its characterization

PHB-silver nanocomposite (PHB-AgNc) was synthesized biologically by utilizing a dairy-industry by-product, cheese whey permeate as a substrate for Bacillus megaterium. The single-step synthesis of PHB-AgNc was further confirmed by UV–vis spectroscopy and GC-MS analysis. Further, the extracted PHB-Ag Nc was characterized by employing various techniques such as TEM, SEM, FTIR, NMR, Zeta Potential, and DLS analysis. Mechanical properties such as elongation at break, tensile strength, and Young's Modulus were found to be 1.305%, 35.42, and 1.058 N/mm², respectively. The nanocomposite was found to be stable, polydispersive, and hydrophobic. It exhibited a degradation temperature of 340 °C and portrayed significant antimicrobial resistance against common food pathogens such as E.coli and Pseudomonas spp. Batch fermentation study was carried out for a period of 96 h in a 14 L bioreactor. The highest biomass and nanocomposite yield obtained was 5.8 and 2.4 g/L, respectively. The highest product productivity concerning biomass was found to be 0.012 h⁻¹ at 12 h. The film's migration properties were tested for various food stimulants, and the values obtained were less than the overall migration limit established for food contact materials; hence, the film was found to be appropriate for food packaging applications.     

Antibacterial,antioxidant and photocatalytic activity of novel Rubus ellipticus leaf mediated silver nanoparticles

Nanotechnology is an emerging field of science that has significant applications in applied sciences. In this study, silver nanoparticles (SNPs) were synthesized utilizing the leaf filtrate of Rubus ellipticus. SNPs were characterized using UV–visible spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction patterns to determine their morphology and chemical composition. The surface plasmon resonance of SNPs revealed a peak at 415 nm. The synthesized SNPs were mainly spherical crystals with an average size of 21.43 nm. When compared to plant extract and positive controls (AgNO₃ and penicillin), SNPs demonstrated significant bactericidal activity against all the tested bacteria (gram-positive and gram-negative). The most effective bactericidal activity was found against Pseudomonas aeruginosa, with a minimum inhibitory concentration of 1.25 µg/mL. In addition, a dose-dependent antioxidant activity of SNPs was found against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical with an average IC50 value of 72.84 µg/mL. The photocatalytic activity of Methylene blue (MB) dye decomposition under sunlight was studied. The results showed that MB degraded by 98 % after 150 min in the sun. Overall, the findings of this study indicate that R. ellipticus biosynthesized SNPs may have bactericidal and photocatalytic effects.     

Superatom-in-Superatom Nanoclusters: Synthesis,Structure, and Photoluminescence

We report a new strategy in which a thiolate-protected Ag₂₅ nanocluster can be doped with open d-shell group 8 (Ru, Os) and 9 (Ir) metals by forming metal hydride (RuH₂, OsH₂, IrH) superatoms with a closed d-shell. Structural analyses using various experimental and theoretical methods revealed that the Ag₂₅ nanoclusters were co-doped with the open d-shell metal and hydride species to produce superatom-in-superatom nanoclusters, establishing a novel superatom doping phenomenon for open d-shell metals. The synthesized superatom-in-superatom nanoclusters exhibited dopant-dependent photoluminescence (PL) properties. Comparative PL lifetime studies of the Ag₂₅ nanoclusters doped with 8–10 group metals revealed that both radiative and nonradiative processes were significantly dependent on the dopant. The former is strongly correlated with the electron affinity of the metal dopant, whereas the latter is governed predominantly by the kernel structure changed upon the doping of the metal hydride(s).     

The enhanced photo-stability of defective Ag3PO4 tetrahedron prepared using tripolyphosphate

Ag₃PO₄ is an excellent photocatalyst under visible light irradiation. However, the low stability due to photo-corrosion is still an obstacle in its application. It is a big challenge to improve stability using synthesis modification. Here, the photocatalyst stability enhancement was successfully prepared by tripolyphosphate. Photocatalyst was prepared by reacting AgNO₃ solution with STPP (sodium tripolyphosphate) solution to form a white suspension. The addition of phosphate solution to the white suspension produces yellow Ag₃PO₄ with a new type of defective photocatalyst. The XPS measurement showed that the increase of STPP concentration significantly decreased the Ag/P atomic ratio, indicating the silver vacancy formation on the surface of Ag₃PO₄. The photocatalytic reaction formed a metallic Ag with a lower d-space in the cube structure occurred in the silver vacancy of Ag₃PO₄. This defect increases the interaction of metallic silver and Ag₃PO₄. The enhanced photo-stability might be induced by metallic silver that can act as a photogenerated electron acceptor.     

纳米银参与的多潘立酮化学发光分析法研究

在碱性介质中,基于多潘立酮对纳米银(AgNPs)增敏Luminol-KMnO4化学发光体系发光信号的抑制作用,结合流动注射技术,提出了测定多潘立酮的化学发光分析新方法。在选定的流路和实验条件下,该方法测定多潘立酮的线性范围为1.0×10-8~5.0×10-6 g/mL,检出限为1.05×10-9 g/mL。对1.0×10-6 g/mL的多潘立酮溶液平行测定11次,其相对标准偏差(RSD)为1.7%。该法灵敏、准确、快速,用于样品中多潘立酮的测定,结果满意。