Presence Of AgNO3 Research Articles

Syntheses of Phosphonylated Pyrido-Dihydrofurans by Regioselective 5-Exo-dig Addition to Carbon-Carbon Triple Bond Catalyzed by AgNO3.

The tandem nucleophilic addition-cyclization reaction of o-alkynylpyridinecarbaldehyde 1 with dialkyl phosphites 2 took place very smoothly in the presence of AgNO3 under base conditions in DCE at 50 °C. In all cases, the reaction proceeded in a regioselective manner leading to the 5-exo-dig phosphonylated pyrido-dihydrofurans 3 in moderate to good yields.

Pathway control in metallosupramolecular polymerization of a monoalkynylplatinum(ii) terpyridine complex through competitive complex formation.

Understanding the pathway complexity of supramolecular polymerization in biomimetic systems has been a challenging issue due to its importance in the development of rationally controlled materials and insight into self-assembly in nature. We herein report a kinetic trapping strategy as a new methodology on how to control the pathway of metallosupramolecular polymerization by employing secondary metal ions and/or ligands which form competitive complex species. For this, we proposed monoalkynylplatinum(ii) metalloligand (Pt-L1) derived from a bis(amideterpyridine) receptor with one unoccupied terpyridyl terminal as a coordination site for the secondary metal ion (Ag+ or Fe2+). The inherent pathway complexity intrinsic to the Pt-L1-anchored supramolecular polymerization has been modulated through the incorporation of Ag+ or Fe2+. During the supramolecular polymerization of Pt-L1 in the presence of Ag+ and Fe2+, the added secondary ligand bpy (4,4'-dimethyl-2,2'-bipyridine) or DA18C6 (1,14-diaza-18-crown-6) form complexes as kinetic species, thereby inhibiting spontaneous polymerizations. The supramolecular polymer (SP-I), with a spherical structure composed of Pt-L1 in the absence of metal ions as a kinetic product, did not transform into the thermodynamic product, namely supramolecular polymer (SP-III) with a left-handed fiber structure, due to a high energy barrier. However, the supramolecular polymer (SP-II) with a left-handed fiber structure, which was formed by Pt-L1 in the presence of AgNO3, converted to SP-III upon the addition of NaCl. Additionally, SP-II transformed into supramolecular polymer (SP-IV) upon the addition of Fe(BF4)2, through an on-pathway process. Both the morphological and emissive characteristics of the resulting supramolecular polymers can be fine-tuned via the Pt⋯Pt or Ag⋯Ag interactions as well as through the changes of the coordination geometry depending on the existing Ag+ or Fe2+ ions. The present results have important implications in expanding the scope of pathway complexity to produce a variety of products via kinetically controlled processes involving secondary metal ions and ligands.

In Vitro Shoot Multiplication and Regeneration of the Recalcitrant Rocket (Eruca sativa Mill.) Variety Domaća Rukola

Eruca sativa is known in traditional medicine for its therapeutic effects, while young plants are used as a salad or green food. Recently, the consumption of rocket has increased considerably, so it has become very important for breeders. Plant tissue culture provides a platform to overcome the problems in improving this species. In the present study, an efficient protocol for in vitro shoot regeneration and propagation of recalcitrant rocket variety Domaća rukola was studied. Murashige and Skoog (MS, 1962) medium containing 0.1 mg L−1 BA and frequent subculture over a period of three weeks proved to be optimal for shoot multiplication with a multiplication index of over 3 and only 8.72% of hyperhydrated shoots without necrosis. Different concentrations of 2,4-D, BA, or TDZ in combination with NAA, with or without the presence of AgNO3, were tested for de novo shoot organogenesis (DNSO) from seedling explants. The hypocotyl explants cultured on MS with a combination of TDZ1.0+NAA0.1+AgNO3 5.0 mg L−1 regenerated viable shoots with the highest rate (25.38%) and an average number of 2.18 shoots per regenerating explant. Somatic embryogenesis from immature zygotic embryos proved to be the best way to regenerate a recalcitrant rocket cultivar. The highest embryogenic efficiency was achieved in explants cultured on MS medium containing 1.0 mg L−1 2,4-D with a frequency of 76.64% and 5.13 mean number of regenerated somatic embryos per explant, which were further converted into normal plants. Additionally, in vitro-produced rocket shoots could serve as a possible promising source for the production of flavonoid kaempferol with proven antioxidant properties.

Green preparation of electrically conductive solution blow spun nanofibers from recycled polyethylene terephthalate via plasma-assisted oxidation-reduction.

Simple and green strategy was described for the development of multifunctional polyester nanofibers (PNFs). Solution blow spinning (SBS) technology was applied to in situ immobilize nanocomposites of polyaniline (PANi) and silver nanoparticles (AgNPs) into plasma-treated polyester nanoscaled fibers prepared. The polyester nanofibers were prepared from recycled polyethylene terephthalate waste, which was exposed plasma-curing and a REDOX reaction in the presence of AgNO3, aniline, and CH3COONH4. Plasma-catalyzed oxidative polymerization of aniline to polyaniline together with a reductive process of Ag+ to silver nanoparticles led to their enduring insoluble dispersion into the surface of polyester nanofibers. By taking the advantage of the PANi oxidation, AgNPs were precipitated from an aqueous medium of AgNPs. The morphological properties were investigated by various analytical techniques. The polyester fiber diameter was determined in the range of 450-650nm. In addition, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were utilized to examine AgNPs, demonstrating diameters of 4-20nm. The plasma-uncured AgNPs/PANi immobilized nanofibrous film displayed weak absorption bands at 399nm and 403nm upon increasing the concentration of AgNPs. On the other hand, the plasma-cured AgNPs/PANi immobilized nanofibers displayed strong absorption bands at 526nm and 568nm upon increasing the concentration of AgNPs. The AgNP-induced antimicrobial performance and the PANi-induced electrically conductivity were explored. The prepared PNFs showed high UV protection.

Engineered Cobalt Single-Atoms@BiFeO3 Heteronanostructures for Highly Efficient Solar Water Oxidation.

Efficient charge-carrier separation and their utilization are the key factors in overcoming sluggish four-electron reaction kinetics involved in photocatalytic oxygen evolution. Here, a novel study demonstrates the significance of Na2 S2 O8 as a sacrificial agent in comparison to AgNO3 . Resultantly, BiFeO3 (BFO) and titanium doped-oxygen deficient BiFeO3 (Ti-BFO-R) nanostructures achieve ≈64 and 44.5 times higher O2 evolution in the presence of Na2 S2 O8 compared to AgNO3 as a sacrificial agent, respectively. Furthermore, the presence of Co single atoms (Co-SAs) deposited via immersion method on BFO and Ti-BFO-R nanostructures led to achieving outstanding O2 evolution at a rate of 16.11 and 23.89mmol g-1 h-1 , respectively, which is 153 and 227.5 times higher compared to BFO (in the presence of AgNO3 ), the highest O2 evolution observed for BFO-based materials to date. The successful deposition of Co-SAs is confirmed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC HAADF-STEM) and X-ray absorption near-edge structure (XANES). The charge transfer investigations confirm the significance of Co-SAs on BFO-based photocatalysts for improved charge-carrier separation, transport, and utilization. This novel study validates the excellent role of Na2 S2 O8 as a sacrificial agent and Co-SAs as a cocatalyst for BFO-based nanostructures for efficient O2 evolution.

Alginate-enabled green synthesis of S/Ag1.93S nanoparticles, their photothermal property and in-vitro assessment of their anti-skin-cancer effects augmented by a NIR laser

We report herein the design and synthesis of colloidally-stable S/Ag1.93S nanoparticles, their photothermal conversion properties and in vitro cytotoxicity toward A431 skin cancer cells under the excitation of a minimally-invasive 980 nm near-infrared (NIR) laser. Micron-sized S particles were first synthesized via acidifying Na2S2O3 using biocompatible sodium alginate as a surfactant. In the presence of AgNO3 and under rapid microwave-induced heating, alginate reduced AgNO3 to nascent Ag which reacted with molten S in situ forming S/Ag1.93S nanoparticles. The nanoparticles were characterized using a combination of X-ray diffraction, electron microscopies, elemental analysis, zeta-potential analysis and UV–VIS-NIR spectroscopy. The average particles size was controlled between 40 and 60 nm by fixing the mole ratio of Ag+:S2O32−. When excited by a 980 nm laser, S/Ag1.93S nanoparticles (~40 nm) produced with the least amount of AgNO3 exhibited a respectable photothermal conversion efficiency of circa 62% with the test aqueous solution heated to a hyperthermia-inducing 52 °C in 15 min. At 0.7 W/cm2, the viability of A431 skin cancer cells incubated with 7.0 ± 0.2 μg/mL of S/Ag1.93S nanoparticles reduced to 14 ± 0.6%, while an A431 cell control maintained an 80% cell viability. These results suggested that S/Ag1.93S nanoparticles may have good potential in reducing metastatic skin carcinoma.

Silver-catalyzed radical reaction of 2H-indazoles with 1,3-dicarbonyl compounds to access 3-dicarbonyl indazoles

A convenient strategy for the direct synthesis of 3-substituted-2 H -indazole derivatives was developed in the presence of AgNO 3 /Na 2 S 2 O 8 under mild reaction conditions. The reaction affords a series of 1,3-dicarbonyl-2 H -indazoles products with yields of up to 82%. The mechanism of the strategy suggests that the reaction proceeds through a radical pathway. Moreover, this strategy provides a new protocol for the synthesis of functionalized 2 H -indazoles. • A direct synthesis of 3-substituted-2 H -indazole derivatives based on Ag(I)-peroxodisulfate system was developed. • This heterocyclic formation process features mild reaction conditions, simple execution and broad substrate scope. • Product will be further used directly to synthesize more structurally diverse polyheterocycles.

Dynamic Transformation of a Ag+-Coordinated Supramolecular Nanostructure from a 1D Needle to a 1D Helical Tube via a 2D Ribbon Accompanying the Conversion of Complex Structures.

We report a unique dynamic morphology transformation of a Ag+-coordinated supramolecular nanostructure accompanying the conversion of complex structures in aqueous solution. In the presence of AgNO3 (1.0 equiv), the achiral bipyridine-based ligand 1G, possessing hydrazine and glycine moieties, preferentially generated a 1D needle-like structure (nanostructure I) based on the 1GAgNO3 complex (1G:Ag+ = 1:1) as a metastable product. Nanostructure I was then transformed into nanostructure II, which was composed of the 1G3Ag2(NO3)2 complex (1G:Ag+ = 3:2) as the thermodynamically stable product. This nanostructure exhibited a 1D helical tubular structure with a uniform diameter via a 2D ribbon as an intermediator, which led to the generation of a circular dichroism (CD) signal with right-handed (P-type) helicity. The observed dynamic transformation was attributed to formation of the thermodynamically favored helical 1G3Ag2(NO3)2 complex. In addition, the helical 1G3Ag2(NO3)2 complex acted as an initiator in the transformation from the 1D needle-like structure to the 1D helical tube via a 2D ribbon. The enhanced ΔG° value of nanostructure II compared to that of nanostructure I confirmed that nanostructure II is thermodynamically stable. More importantly, the transformation of supramolecular nanostructure I to nanostructure II occurred via an "on" pathway, even though the 1GAgNO3 complex was converted to the 1G3Ag2(NO3)2 complex, which did not involve dissociation from nanostructure I into the monomeric 1GAgNO3 complex species. In the kinetic study, the NO3- anion was found to act as an accelerator for the dynamic transformation from nanostructure I to nanostructure II. This result provides the first example of a dynamic transformation of a 1D needle-like structure into a 1D tubular structure via a 2D ribbon structure, accompanied by the conversion of a complex structure and the generation of a large CD signal for the metallo-supramolecular nanostructure. This study may open up new avenues to the understanding of a dynamic morphology transformation process in biological systems.

Synthesis of 5-(4-bromobutyl)-2,3-dimethyl-1,4-benzoquinone and the Solubility Test in n-Octanol/Water Partition System

The modification structure of 1,4-benzoquinone is fascinating in the frame of drug design. The solubility properties of a new drug are important, especially for oral drug administration. The 2-isopropyl-5-methyl-1,4-benzoquinone (known as thymoquinone) which is the major constituent in Nigella sativa seed extract is known as an active compound with poor lipophilicity. Here, we reported the synthesis of 5-(4-bromobutyl)-2,3-dimethyl-1,4-benzoquinone which analog with thymoquinone having higher lipophilicity. The synthesis proposed by oxidation reaction of 2,3-dimethyl-1,4-hydroquinone (1) with H2SO4 followed by bromoalkylation reaction using bromopentanoic acid in the presence of AgNO3 and (NH4)2S2O8. The oxidation product 2,3-dimethyl-1,4-benzoquinone (2) and alkylated-quinone 5-(4-bromobutyl)-2,3-dimethyl-1,4-benzoquinone (3) were obtained in 52.64% and 5.85%, respectively. The FTIR analysis of 3 showed the additional C-Br stretching at 562 cm−1. The solubility test in n-octanol/water system using HPLC gave the log P value of 5-(4-bromobutyl)-2,3-dimethyl-1,4-benzoquinone (3) is 2.99, higher than thymoquinone. By this result, it is suggested that the modification of 1,4-benzoquinone by bromo alkylating agent increased the solubility of the compound.

Direct Synthesis of Sulfonylated Spiro[indole-3,3'-pyrrolidines] by Silver-Mediated Sulfonylation of Acrylamides Coupled with Indole Dearomatization.

A dearomative tandem spiro-cyclization reaction of N-[(1H-indol-3-yl)methyl]methacrylamide derivatives with sulfinate sodium in the presence of AgNO3 and K2CO3 is reported, which produced sulfonylated spiro[indole-3,3'-pyrrolidines] in medium to excellent yields. The characteristics of this transformation contain good functional group tolerance and ease of operation.

Syntheses, structures and photocatalytic properties of ruthenium complexes bearing L-methionine ligands

Treatment of [(η6-C6H6)RuCl2]2 or [(η6-p-cymene)RuCl2]2 with two equiv. of L-methionine in the presence of AgNO3 and NaOMe gave mononuclear ruthenium(II) complexes [(η6-C6H6)Ru(L-met)](NO3) (1) and [(η6-cymene)Ru(L-met)](NO3) (2), respectively. Interactions between equal equiv. of L-methionine and [Ru(CO)2Cl2]n, [Ru(bpy)2Cl2]·2H2O (bpy = 2,2′-bipyridine), [Ru(NO)(PPh3)2Cl3], (Et4N)[Ru(CH3CN)2Cl4] or cis-[Ru(DMSO)4Cl2] (DMSO = dimethylsulfoxide) resulted in isolation of the expected ruthenium complexes [(CO)2Ru(L-met)Cl] (3), [(bpy)2Ru(L-met)]Cl (4), [Ru(L-met)(NO)(PPh3)Cl]Cl (5), [Ru(L-met)(CH3CN)Cl2] (6) and [Ru(L-met)(DMSO)2Cl] (7), respectively. Reaction of [Ru(COD)Cl2]2 (COD = 1,5-cyclooctadiene) with L-methionine gave a dinuclear ruthenium complex [(COD)Ru(μ-S-L-met)(μ-Cl)RuCl(L-metNMe2)] (8). Complexes 1−8 were characterized by microanalyses, IR, NMR and UV–vis spectroscopies. The structures of complexes 1, 2, 4 and 8 have been unambiguously established by single-crystal X-ray crystallography. The photocatalytic properties for hydrogen production by water splitting of complexes 1, 2, 4 and 8 under visible light (λ > 420 nm) were also investigated.

One-Step Photochemical Green Synthesis of Water-Dispersible Ag, Au, and Au@Ag Core-Shell Nanoparticles.

A simple and green synthetic protocol for the rapid and effective preparation of Ag, Au and Au@Ag core-shell nanoparticles (NPs) is reported based on the light irradiation of a biocompatible, water-soluble dextran functionalized with benzophenone (BP) in the presence of AgNO3 , HAuCl4 , or both. Photoactivation of the BP moiety produces the highly reducing ketyl radicals through fast (<50 ns) intramolecular H-abstraction from the dextran scaffold, which, in turn, ensures excellent dispersibility of the obtained metal NPs in water. The antibacterial activity of the AgNPs and the photothermal action of the Au@Ag core-shell are also shown.

Highly Enantioselective Synthesis Using Prolinol as a Chiral Auxiliary: Silver-Mediated Synthesis of Axially Chiral Vinylallenes and Subsequent (Hetero)-Diels-Alder Reactions.

Using (S)-prolinol as a chiral auxiliary, axially chiral vinylallenes with excellent enantiopurity (up to >99% enantiomeric excess (ee)) were readily prepared from optically pure propargylamines in the presence of AgNO3 under microwave irradiation. Subsequent (hetero)-Diels-Alder reaction of these axially chiral vinylallenes with azodicarboxylates or maleimides on water demonstrates excellent axial-to-point chirality transfer (up to 99% ee).

In vitro Antibacterial Activity of Maleamates Functionalized-Chitosan-PVC/Silver Nanocomposites

Poly(vinyl chloride), PVC, was aminated via reaction with ethylenediamine before conjugation with functionalized chitosan (Cs) using chloroacetyl chloride as a linking agent. Cs was functionalized with p-nitrophenyl (MA), p-anisyl (MB), and p-toluyl (MC) maleamates. Functionalized Cs-PVC conjugation was effected in the presence of AgNO3 (3% w/w) producing MA-CCs-PVC/Ag nanocomposites via a one-pot synthesis method. The chemical structures of the synthesized samples were studied by FTIR spectroscopy. Scanning and transmission electron microscopy were performed to investigate the morphology of the nanocomposites, while the EDX spectrum determined Ag contents in the prepared samples. Values of water uptake measurements determined the swelling properties of the prepared nanocomposites. The antibacterial efficiency of the modified polymers was investigated against two Gram-positive (Bacillus subtilis and Staphylococcus aureus), and two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria, in comparison with that of Cs, amino-PVC (Am-PVC), and ampicillin as a reference antibacterial agent.

Synthesis of Complex Nanoparticle Geometries via pH-Controlled Overgrowth of Gold Nanorods.

We show that many complex gold nanostructures such as the water chestnut, dog bone, nanobar, and octahedron, which are not easily accessible via a direct seed-growth synthesis approach, can be prepared via overgrowth of the same gold nanorods by varying pH and Ag concentrations in the growth solution. Overgrown nanostructures’ shapes were determined by the rate of gold atom deposition, which is faster at higher pH. In the presence of AgNO3, codeposition of gold and silver atoms affects the shapes of overgrown nanostructures, particularly at high pH.

High quantum efficiency of photocatalytic water oxidation over the TiO2/MMO nanocomposite under visible-light irradiation

The titanium dioxide/ZnAl-layered double hydroxide (TiO2/ZnAl-LDH) nanocomposite was first prepared using the co-precipitation method, and the TiO2/metal mixed oxide (TiO2/MMO) was then fabricated by annealing the TiO2/ZnAl-LDH nanocomposite at 430 °C. The obtained materials were characterized by means of techniques, such as field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–visible diffuse reflectance spectroscopy (DRS), and N2 adsorption-desorption (BET). Photocatalytic activities of the TiO2/MMO nanocomposite was evaluated for O2 generation from aqueous solutions in the presence of AgNO3 (1 mmol) as the sacrificial agent at neutral pH and room temperature under visible-light irradiation. It is found that photocatalytic activity of the TiO2/MMO sample was better than that of the TiO2/ZnAl-LDH sample, which could be attributed to the reduction in bandgap energy, low electron-hole recombination, and high surface area. An O2 generation rate of 371 μmol/(g h) was achieved over 20 mg of the TiO2/MMO nanocomposite photocatalyst, and the quantum efficiency for O2 generation was 84% at 400 nm. Such a quantum efficiency was the highest value obtained over the TiO2/MMO sample under visible-light illumination. This study presents a novel approach for water oxidation using the visible-light-responsive TiO2/MMO nanocomposite photocatalyst, which might be applied as a promising candidate in solar energy conversion and environmental science for highly efficient O2 generation.

THE BIOSYNTHESIS OF SILVER NANOPARTICLES BY CYTOPLASMIC FLUID OF CORIOLUS VERSICOLOR

The aim of this study is to investigate the production conditions of silver nanoparticles (NPs) in the presence of AgNO3 with the fungal cytoplasmic fluid (FCF) of white rot fungus Coriolus versicolor. In this study, parameters such as pH, AgNO3 concentration and FCF ratio of C. versicolor were optimized. C. versicolor was grown in SBM and then kept in ultrapure water to obtain FCF for synthesis of the nanoparticle. Nanoparticle formation was monitored by UV spectrophotometry at 420 nm wavelength and the silver nanoparticles were imaged by SEM. In the optimization study, it was found that at pH 5.0, 1.5 mM AgNO3 and 50% FCF containing medium was found to provide optimal conditions for the synthesis of the silver nanoparticle. The nanoparticles were spherical and varied between 15-35 nm.

Ag(i)-mediated self-assembly of anisotropic rods and plates in the surfactant mixture of CTAB and Pluronics.

One-dimensional (1D) metallogels are commonly observed in metal-coordinated complexes, but there are not many examples of soft crystalline solids which are generated by the self-assembly of metal–polymer complexation in a non-gel state. In a continued effort to obtain 1D materials by utilizing the tendency of Pluronic triblock copolymers to be micellized anisotropically at an elevated temperature, we investigate Ag(i)-mediated self-assembly of the surfactant mixture of Pluronic copolymers and cetyltrimethylammonium bromide (CTAB). At sufficiently high temperature, Pluronic copolymers are known to organize into many crystalline mesophases, such as body-centered-cubic, hexagonal, and lamellar phases. Four Pluronics of L-31, L-64, P-123, and F-108 were studied, and at the concentration of 17.9%, macroscale 1D rods with the aspect ratios ranging from 3.07 to 12.8 are obtained. At the concentration of 35.7%, anisotropic two dimensional (2D) planar plates are observed. These planar structures were believed to be generated from 2D lamellar mesophases, which is consistent with the general phase diagram of Pluronic copolymers that shows lamellar phase with the highest concentration. In the absence of ascorbic acid, rods and plates of larger size are produced. Rather than as a reductant, ascorbic acid is thought to play the roles of an agent to increase the hydrophilicity, and as a mediator to determine the dimension of rods and plates by hindering the long range self-assembly of alkyl chains. Dehydration by the addition of AgNO3, and the increase of hydrophobicity enable self-assembly of alkyl groups of CTAB and Pluronics and promote the formation of crystalline soft solids.

Photocatalytical properties of organic-inorganic copolymers of poly(titanium oxide) in the 4-nitrophenol decomposition

Optically transparent materials of poly(titanium oxide) in organic polymer matrix, doped by silver or gold nanoparticles of medium size (9 and 12 nm respectively), were synthesized in the reaction of titanium iso-propoxide with hydroxyethylmethacrylate in the presence of AgNO3 and HAuCl4 as dopants. The materials exhibite activity as heterogeneous photocatalysts. The decomposition of p-nitrophenol was observed in aqueous solutions under light irradiation in the presence of the obtained materials. This reaction can be initiated by both UV- and visible light. The useing of copolymers doped by Au or Ag nanoparticles lead to increased p-nitrophenol decomposition up to 70 and 85% (UV-irradiation) and up to 90% (λ > 410 nm). It was determined that the rate constants of the reactions in this case were: kAg = (23.11 ± 0.16)∙10−2 s-1 and kAu = (8.05 ± 0.13)∙10−2 s-1.

Phosphorus Radical-Initiated Cascade Reaction To Access 2-Phosphoryl-Substituted Quinoxalines.

An effective radical cascade cyclization strategy was developed, by which a wide range of 2-phosphoryl-substituted quinoxalines were prepared in one pot via reaction of ortho-diisocyanoarenes with diarylphosphine oxides in the presence of AgNO3 under mild reaction conditions.