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A green approach for the biosynthesis of silver nanoparticles (AgNPs) was developed using Diplazium esculentum aqueous extract as green reductant. The bio-stabilized AgNPs were characterized by UV–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), and high-resolution transmission electron microscopy (HRTEM). The formation of AgNPs was indicated by the colour change and the absorption peak at 449 nm in the UV–Vis spectrum. FTIR spectral analysis suggested the possible biomolecules associated with the reduction of silver ions. The crystalline and face-centered cubic (fcc) structure of AgNPs was obtained by the XRD study. HRTEM analysis showed that the biosynthesized AgNPs composed of quasi-spherical, hexagonal, and ellipsoidal shapes with an average particle size of 23.385 ± 8.349 nm. The biosynthesized AgNPs exhibited good catalytic activity up to 91% reduction of Methylene blue (MB), which followed a reductive pathway rather than a photocatalytic route. The catalytic reduction follows a pseudo-first-order reaction with a rate constant of 0.1051 min-1. The disc diffusion technique (DDT) and minimal inhibitory concentration (MIC) results showed significant antibacterial capability against Gram-positive (Escherichia coli ATCC 11,229) and Gram-negative (Staphylococcus aureus ATCC 6538) bacteria. [ABSTRACT FROM AUTHOR]

An environmentally benign magnetic gold nanoparticles (AuNPs) catalyst supported onto thioctic acid functionalized silica-coated magnetite nanoparticles, Au–RS–SR–NH–SiO2–Fe3O4,without employing any toxic reductant or capping agent was successfully synthesized. The Phaleria macrocarpa (Scheff.) Boerl (P. macrocarpa) fruit aqueous extract was used as the reducing and stabilizing agents for the biosynthesis of AuNPs. The catalytic performance of the magnetic AuNPs catalyst was evaluated for the reduction of 4-nitrophenol into 4-aminophenol in the presence of NaBH4. A three-factor Box–Behnken design coupled with response surface methodology was applied to evaluate the effects of several operating parameters, namely, volume of NaBH4, 4-nitrophenol concentration, and weight of Au–RS–SR–NH–SiO2–Fe3O4 on the conversion of 4-nitrophenol. The reduction of 4-nitrophenol using Au–RS–SR–NH–SiO2–Fe3O4 was welldescribed by a quadratic polynomial model. A significant quadratic model with p value ˂.0001 and R2 = 0.9958 was achieved using the analysis of variance (ANOVA). The conversion of 4-nitrophenol to 4-aminophenol was maintained at 90% after five cycles. [ABSTRACT FROM AUTHOR]

The combination of aggregation-induced emission (AIE) and liquid crystal properties generates solid-state efficient luminescent liquid crystal materials. Here in, we reported the synthesis of 1,3,5-triazine-2,4,6-tricarboxamide and utilized it as a supramolecular organic motif for the AIE-active liquid crystal material. The compound exhibits high-intensity emission maxima at 417 and 468 nm in the solid state with excitation at 254 nm, whereas it shows weak emission in the solution phase. Also, this compound behaves as liquid crystalline material and shows columnar hexagonal mesophase with endothermic peaks at 73.4°C, 185.6°C, and exothermic peaks were observed at 181. 9°C and 66.1oC with focal conic fan shape texture. The thermal data showed that the compound is stable up to 200°C. [ABSTRACT FROM AUTHOR]

The combination of aggregation-induced emission (AIE) and liquid crystal properties generates solid-state efficient luminescent liquid crystal materials. Here in, we reported the synthesis of 1,3,5-triazine-2,4,6-tricarboxamide and utilized it as a supramolecular organic motif for the AIE-active liquid crystal material. The compound exhibits high-intensity emission maxima at 417 and 468 nm in the solid state with excitation at 254 nm, whereas it shows weak emission in the solution phase. Also, this compound behaves as liquid crystalline material and shows columnar hexagonal mesophase with endothermic peaks at 73.4°C, 185.6°C, and exothermic peaks were observed at 181. 9°C and 66.1°C with focal conic fan shape texture. The thermal data showed that the compound is stable up to 200°C. [ABSTRACT FROM AUTHOR]

The effects of precipitation temperature on both structural and magnetic properties of polyethylene glycol-coated MnZnFe O nanoparticles are presented. Samples were prepared via co-precipitation method at different precipitation temperatures ranged 25-100 C. X-ray diffraction analysis revealed that both crystallite size and lattice constant of the nanoparticles increased with increasing of temperature. FESEM images verified the existence of crystalline ferrites of diameter ranged 7.49-9.41 nm. FTIR spectra evidenced the effect of precipitation temperature on Fe -O stretching vibration in the ferrites. These MnZnFe O nanoparticles exhibited the highest saturation magnetization 20.938 emu/g at 75 C. Correlations among precipitation temperature alteration, structural morphology, and magnetic response are established. [ABSTRACT FROM AUTHOR]

A green and cost-effective biosynthetic approach for the preparation of icosahedral gold nanoparticles (AuNPs) using an aqueous leaf extract ofPolygonum minusas reducing and stabilising factor is described. The reduction of Au3+ions to elemental Au rapidly occurred and is completed within 20 minutes at room temperature. The size of the nanoparticles is highly sensitive to the AuCl4−/leaf extract concentration ratio and pH. Transmission electron microscopy and X-ray diffraction data indicated that the nanoparticles were in a crystalline shape (face-centred cubic), mostly icosahedral and nearly monodispersed with an average size of 23 nm. Cyclic voltammetric studies suggested that flavonoids, such as quercetin and myricetin present in the leaf extract had a tendency to donate electrons to Au3+ions and the formation of elemental Au was possible due to the transfer of electrons from these flavonoids to Au3+ions. Infrared absorption of the AuNPs and the leaf extract revealed that the oxidised (quinone) form of quercetin and myricetin were presumably the main stabilising agents in the formation of stable nanoparticles. The present biosynthesis of AuNPs was simple, rapid, cost-effective and environmentally friendly. The newly prepared biostabilised icosahedral AuNPs show good catalytic activity in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). [ABSTRACT FROM AUTHOR]

A series of novel polycyclic structures, with an imidazothiazole central core, were successfully synthesized through the anodic oxidation of catechols in the presence of 2-imidazolidine thione, as nucleophiles in aqueous solution. The cyclic voltammetric results indicated that one-pot multi-step sequential reactions occur between the electrochemically derived o-benzoquinones intermediates and nucleophiles affording fused polyheterocyclic compounds. The mechanism of these catalyst-free, tandem reactions are proved as ECECE or ECECCE pathways using potentiostatic and galvanostatic coulometries. In addition, the electrosyntheses of fused imidazo[2,1- b]thiazoles have been successfully performed in ambient conditions in an undivided cell using an environmentally friendly method with high atom economy and current efficiency. The novel fused polyheterocycles were fully characterized by FT-IR, H NMR, C NMR, and HR-MS spectrometric methods. Graphical abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Four air and moisture-stable palladium(II)-Schiff base complexes, N,N'-bis(-methylsalicylidene)propane-1,3-diamine palladium(II) (2a), N,N'-bis(4-methyl--methylsalicylidene)propane-1,3-diamine palladium(II) (2b), N,N'-bis(3,5-di-tert-butylsalicylidene)propane-1,3-diamine palladium(II) (2c), and N,N'-bis(4-methoxy-salicylidene)propane-1,3-diamine palladium(II) (2d), have been successfully synthesised and characterised by CHN elemental analyses and conventional spectroscopic methods. These complexes were investigated as catalysts in the phosphine-free Mizoroki-Heck cross-coupling reactions of aryl bromides with methyl acrylate. [ABSTRACT FROM AUTHOR]