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We describe an efficient and versatile method for the direct C−H arylation of xanthines with aryl halides using Pd/P(o‐tolyl)3 as catalyst and Ag2O as an additive. Silver salts have been frequently used as an additive in the Pd‐catalyzed C−H bond activation reactions albeit in excessive amounts (2 to 4 eq.). Herein, we use of a stoichiometric amount (0.1 to 1 eq.) of Ag2O to obtain the optimum yields of C‐8 arylated products. This method exhibits broad substrate scope and enables synthesis of a wide range of xanthine derivatives by variation of aryl component at the C‐8 position. A key advantage of silver additive is that it reduces the catalyst loading and time required for the completion of reactions. Although kinetic experiments show that the inclusion of silver salt accelerates the rate of reaction, catalytic role of silver salt could not be conceived since the C−H bond cleavage is not a rate determining step. Silver salt presumably act as a terminal oxidant in the catalytic cycle and assist the regeneration of Pd catalyst. Moreover, preliminary assessment of biological activities of xanthines demonstrates that the C‐8 arylated xanthines derivatives efficiently inhibit the α‐Synuclein fibrillation, a key factor behind Parkinson's disease. [ABSTRACT FROM AUTHOR]

The synthesis of Cyanobacteria‐mediated nanoparticles has attracted great attention due to its ecofriendly, cost‐effective and biocompatible properties. Silver nanoparticles (AgNPs) are used in different areas such as medicine, household products, disinfectants or food storage. The present study aimed the biosynthesis of AgNPs from Cyanobacterial Chroococcus sp. and their antimicrobial activities on some important pathogen bacterial species. According to the obtained data, optimal conditions for synthesis of AgNPs were extract rate 3 : 1 v/v (cell extract/AgNO3), silver salt concentration 10 mM, pH 7, temperature 60 °C and time 30 minutes. The surface plasmon resonance peak of AgNPs was observed at 420–430 nm, and AgNPs were well‐dispersed spherical with an average size of 11–13 nm in diameter by TEM. SEM‐EDX analysis revealed a strong signal of silver. With FTIR analyzes, shift in the absorption bands after the AgNPs formation was confirmed. X‐ray diffraction analysis exhibited that the AgNPs were cubic crystalline shape. Zeta potential of AgNPs showed ‐ 20 mV. The AgNPs strong showed antibacterial activity on an opportunistic bacterial pathogens of Micococcus luteus, Bacillus subtilis and Pseudomonas aeroginosa. The effective and rapid synthesis of Chroococcus‐mediated AgNPs and their strong antimicrobial effects can create an important potential for their use in biomedical and environmental applications. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus is the Gram-positive, immobile, round-shaped bacterium usually existing on wounds, marine environments, and contaminated food. α-Hemolysin (also called -toxin), a common pore-forming toxin that presents in most S. aureus strains with the ability to penetrate the host cell membrane, leading to osmotic swelling and cell death, appears to be a potential biomarker for detection. Based on a sandwich format, this study developed a lateral flow immunoassay (LFIA) targeting -toxin to detect S. aureus. Silver enhancement method was applied to enhance the test line's signal and, therefore, improve the limit of detection (LOD). This method relies on the accumulation on AuNP surface of silver atoms which come from silver nitrate salt after being reduced by reducing agent. The developed LFIA could detect the target antigen within approximately 20 min with no cross-reactivity. The LOD was increased 10-fold after the silver enhancement, from 105 to 104 CFU/mL of bacteria suspensions. The results indicated that -toxin is a promising target to detect S. aureus. Targeting -toxin not only can be a potential detection approach but also a tool for measuring toxicity. [ABSTRACT FROM AUTHOR]

This research work presents a "green" strategy of weed valorization for developing silver nanoparticles (AgNPs) with promising interesting applications. Two types of AgNPs were phyto-synthesized using an aqueous leaf extract of the weed Andropogon halepensis L. Phyto-manufacturing of AgNPs was achieved by two bio-reactions, in which the volume ratio of (phyto-extract)/(silver salt solution) was varied. The size and physical stability of Andropogon—AgNPs were evaluated by means of DLS and zeta potential measurements, respectively. The phyto-developed nanoparticles presented good free radicals-scavenging properties (investigated via a chemiluminescence technique) and also urease inhibitory activity (evaluated using the conductometric method). Andropogon—AgNPs could be promising candidates for various bio-applications, such as acting as an antioxidant coating for the development of multifunctional materials. Thus, the Andropogon-derived samples were used to treat spider silk from the spider Pholcus phalangioides, and then, the obtained "green" materials were characterized by spectral (UV-Vis absorption, FTIR ATR, and EDX) and morphological (SEM) analyses. These results could be exploited to design novel bioactive materials with applications in the biomedical field. [ABSTRACT FROM AUTHOR]

The structures of five ammonium salt forms of monosulfonated azo dyes, derivatives of 4‐(2‐phenyldiazen‐1‐yl)benzenesulfonate, with the general formula [NH4][O3S(C6H4)NN(C6H3)RR′]·XH2O [R = OH, NH2 or N(C2H4OH)2; R′ = H or OH] are presented. All form simple layered structures with alternating hydrophobic (organic) and hydrophilic (cation, solvent and polar groups) layers. To assess for isostructural behaviour of the ammonium cation with M+ ions, the packing of these structures is compared with literature examples. To aid this comparison, the corresponding structures of four potassium salt forms of the monosulfonated azo dyes are also presented herein. Of the five ammonium salts it is found that three have isostructural equivalents. In two cases this equivalent is a potassium salt form and in one case it is a rubidium salt form. The isostructurality of ion packing and of unit‐cell symmetry and dimensions tolerates cases where the ammonium ions form somewhat different interaction types with coformer species than do the potassium or rubidium ions. No sodium salt forms are found to be isostructural with any ammonium equivalent. However, similarities in the anion packing within a single hydrophobic layer are found for a group that consists of the ammonium and rubidium salt forms of one azo anion species and the sodium and silver salt forms of a different azo species. [ABSTRACT FROM AUTHOR]

Readily accessible, oxygenated 6,6‐dibromobicyclo[3.1.0]hexanes react with isovanillin in the presence of silver salts and an inorganic base to afford ring‐expanded/nucleophilic trapping products of various regio‐ and stereo‐chemical forms. Most such products undergo efficient, intramolecular Mizoroki‐Heck reactions to give the corresponding tetrahydrodibenzofurans. In certain cases, simple variations in the first step of such reaction sequences enables the preparation distinct ring‐expansion products that also cyclise to give tetrahydrodibenzofurans embodying alternative substitution patterns. [ABSTRACT FROM AUTHOR]

Isoxazolopyridines are highly significant for the development of pharmaceuticals and new materials. In continuation of our ongoing research on transformations of 5‐aminoisoxazoles, we report herein a divergent synthesis of two kinds of novel isoxazolo[5,4‐b] pyridines through condensation of 5‐aminoisoxazoles with β,γ‐alkynyl‐α‐imino esters. By using two different silver salts and a phosphoric acid as catalysts, isoxazolo[5,4‐b] pyridine‐α‐carboxylates and isoxazolo[5,4‐b] pyridine‐γ‐carboxylates were constructed as major isomers in moderate to good yields, respectively. The structures of the two kinds of the isoxazolo[5,4‐b] pyridines were confirmed by X‐ray crystal structural analysis. Furthermore, control experiments were conducted to elucidate the reaction mechanism. [ABSTRACT FROM AUTHOR]

The antimicrobial properties and importance of Ag+ have been known since ancient times. However, resistance has started to develop against silver ions, which are used indiscriminately and in high concentrations. Therefore, it is necessary to synthesize new and different silver complexes. In this study, five new molecules were synthesized by green synthesis from amino acids. Firstly, the antimicrobial activities of these molecules were tested with agar well diffusion assay. The result of this work is that it was revealed that the amino acid-silver complexes had very high inhibitory activity against microorganisms such as S. typhimirium, S. epidermidis, P. aeruginosa, K. pneumoniae, Y. pseudotuberculosis, P. vulgaris, E. faecalis, B. subtilis, E. cloaceae, S. aureus, E. coli, L. monocytogenes, C. albicans, and C. parapsilosis. It was found that these molecules have inhibition and bactericidal activity at low concentrations. The MIC, MBC, and MFC values were determined between 1.54–46.5 µg/mL, 24.7–93.1 µg/mL, and 19.0–197.0 µg/mL, respectively. Then, to determine whether these molecules are suitable as antimicrobial agents, cytotoxic and antimutagenic activity tests were performed. The results of the cytotoxicity test showed that these molecules have no cytotoxic effect on the L929 fibroblast cells except some at higher doses (e.g. 10–100 mg/mL). In addition, cell viability stimulation was recorded at some doses below 10 mg/mL. Furthermore, these molecules showed antimutagenic activity at different concentrations 1.17–5.80 µg/mL. The use of these synthesized molecules as antimicrobial agents in many fields such as food and pharmacology seems very promising. [ABSTRACT FROM AUTHOR]

Metals play an important role in the structure and functions of various proteins. The combination of metal ions and peptides have been emerging as an attractive field to create advanced structures and biomaterials. Here, we are reporting the anion‐influenced, silver ion coordinated diverse networks of designed short tripeptide 310‐helices with terminal pyridyl groups. The short peptides adopted classical right‐handed, left‐handed and 310EL‐helical conformations in the presence of different silver salts. The peptides have displayed conformational flexibility to accommodate different sizes and interactions of anions to yield a variety of metal‐coordinated networks. The complexes of metal ions and peptides have shown different porous networks, right‐ and left‐handed helical polymers, transformation of helix into superhelix and 2 : 2 metal‐peptide macrocycles. Further, the metal‐peptide crystals with inherent dipoles of helical peptides gave striking second harmonic generation response. The optical energy upconversion from NIR to red and green light is demonstrated. Overall, we have shown the utilization of short 310‐helices for the construction of diverse metal‐coordinated helical networks and notable non‐linear optical effects. [ABSTRACT FROM AUTHOR]

A discrete liphophilic organotelluroxane macrocycle has been found to catalyse the hydrogen evolution reaction (HER) by proton reduction efficiently. The macrocycle is synthesized via chloride abstraction from bis(p-methoxyphenyl) tellurium dichloride (p-MeOC6H5)2TeCl2 (1) by silver salts AgMX4 (MX4 = BF4−, and ClO4−) resulting in in situ generated di-cationic tetraorganoditelluroxane units; two such units are held together by two weak anions μ2-MX4, bridging to form 12-membered di-cationic macrocycles [((p-MeO-C6H4)2Te)2(μ-O)(μ2-F2BF2)2]2+ (2) and [((p-MeO-C6H4)2Te)2(μ-O)(μ2-O2ClO2)2]2+ (3) stabilized via Te–(μ2-BF4/ClO4), with secondary interactions. The charge is balanced by the presence of two more anions, one above and another below the plane of the macrocycle. Similar reaction at higher temperatures leads to the formation of telluronium salts R3TeX [X = BF4− (4), ClO4− (5)] as a major product. The BF4− anion containing macrocycle and telluronium salt were monitored using 19F NMR. HRMS confirmed the structural stability of all the compounds in the solution state. The organotelluroxane macrocycle 2 has been found to act as an efficient electrocatalyst for proton reduction in an organic medium in the presence of p-toluene sulfonic acid as a protic source. [ABSTRACT FROM AUTHOR]

A set of N-coordinated tellurium(II) compounds containing either C,N-chelating ligands CNR (where CN = 2-(RN＝CH)C6H4, R = tBu or Dipp; Dipp = 2,6-iPr2C6H3) or N,C,N pincer ligands NCNR (where NCN = 2,6-(RN＝CH)2C6H4, R = tBu or Dipp) were synthesized. In the case of C,N-chelated compounds, the reaction of CNDippLi with Te(dtc)2 (where dtc = Et2NCS2) in a 1 : 1 molar ratio smoothly provided the carbamate CNDippTe(dtc) which upon treatment with 2 eq. of HCl provided the chloride CNDippTeCl. In contrast, the analogous conversion of NCNRLi with Te(dtc)2 surprisingly furnished ionic bromides [NCNRTe]Br as a result of the exchange of dtc by Br coming from nBuBr present in the reaction mixture. Furthermore, the reaction of CNDippTeCl or [NCNRTe]Br with silver salts AgX (X = OTf or SbF6) provided the expected tellurenium cations [CNDippTe]SbF6 and [NCNRTe]X. To further increase the Lewis acidity of the central atom, the oxidation of selected compounds with 1 eq. of SO2Cl2 was examined yielding stable compounds [CNtBuTeCl2]X and [NCNtBuTeCl2]X. The oxidation of the Dipp substituted compounds proved to be more challenging and an excess of SO2Cl2 was necessary to obtain the oxidized products [CNDippTeCl2]SbF6 and [NCNDippTeCl2]SbF6, which could solely be characterized in solution. Compounds [CNtBuTeCl2]OTf and [NCNtBuTeCl2]OTf were shown to undergo a controlled hydrolysis to the corresponding telluroxanes. All compounds were studied by multinuclear NMR spectroscopy in solution and for selected compounds solid state 125Te NMR spectroscopy and single-crystal X-ray diffraction analysis were performed. The Lewis acidity of the studied cations was examined by the Gutmann–Beckett method using Et3PO as the probing agent. The Te–N chalcogen bonding situation of selected compounds has also been examined computationally by a set of real-space bonding indicators. [ABSTRACT FROM AUTHOR]

Herein, we report a protocol for the selective δ‐thiolation of aliphatic α‐amino acids catalyzed by a Pd(II)/Ag(I) system. This reaction employs disulfides as thiolating agents and N‐COPy as directing group, providing valuable non‐proteinogenic amino acid derivatives in moderate to good diastereoselectivities and yields. Remarkably, the method is also suitable for the late‐stage functionalization of a dipeptide. Experimental and DFT studies have provided significant insights into the mechanism and underlying factors controlling the selectivity of the process and determining the key role of the silver salt. [ABSTRACT FROM AUTHOR]

The antifungal activity of ten new silver salts of pyrrolo[3,4-c]pyrazol-3-ones and pyrazole-3-carboxamides containing sulfamide groups was studied. Data from in vitro studies and computer predictions of their biological activity were compared. The pharmacophores affecting the antifungal activity were identified. The compound with a 4-ethoxyphenyl substituent in the heterocycle 5-position exhibited the most pronounced antifungal effect (including against Candida non-albicans species) that exceeded the activity of the reference drugs by two times and more (MIC50 = 1.0 mg/L, MIC90 = 15.6 mg/L). This gave grounds for further study of the mechanisms of the revealed antimycotic activity. [ABSTRACT FROM AUTHOR]

Keywords: C-H bond functionalization; fused-ring systems; heteroarenes; homogeneous catalysis; synthetic methods EN C-H bond functionalization fused-ring systems heteroarenes homogeneous catalysis synthetic methods 3526 3534 9 10/19/23 20231102 NES 231102 Graph Pyrazolo[1,5- I a i ]pyrazines are an emerging class of 5,6-fused bicyclic heterocycles that shows huge potential in medicinal chemistry. [22] Nevertheless, the fact that Ag SB 2 sb CO SB 3 sb was more effective than Cs SB 2 sb CO SB 3 sb in the cross-coupling of B 1a b and B 4a b (Table 1) suggested that the silver cation should play a special role. The results showed that both Cs SB 2 sb CO SB 3 sb and Ag SB 2 sb CO SB 3 sb could facilitate H/D exchange of B 1a b at the C7 position. HRMS: I m i / I z i [M + H] SP + sp calcd for C SB 16 sb H SB 13 sb F SB 3 sb N SB 3 sb O SB 3 sb : 352.0909; found: 352.0891. [Extracted from the article]

An asymmetric Michael addition/hydroarylation reaction sequence, catalyzed by a sequential catalytic system consisting of a squaramide and a combination of silver and gold salts, provides a new series of cyclic aza-spirooxindole derivatives in excellent yields (up to 94%) and high diastero- and enantioselectivities (up to 7 : 1 dr, up to >99% ee). Computational study has also been performed. [ABSTRACT FROM AUTHOR]

In ancient, human used silver and silver salts but silver nanoparticles (AgNPs) have recently been found to be accepted as the result of green synthesis. Now a day, silver nanoparticles (AgNPs) have become extremely popular in the field of the sensor due to their remarkable and significant optical, chemical, and electrical properties. In this paper, we have reported the green and reasonably priced synthesis of silver nanoparticles using Acacia confusa leaf extract which acts as both capping as well as reducing agents. The optical sensing and morphology of the as prepared AgNPs were determined using ultraviolet-visible (UV-Visible) and scanning electron microscopy (SEM) analysis. The sensing of Hg2+ ion through colorimetric and optical have been studied by UV-Vis spectroscopy as well as the naked eye. Moreover, the SEM analysis showed that the volume of the extract had no considerable effect on the morphology except for size. The colorimetric and optical sensing study revealed that the as-synthesized AgNPs exhibited a good response with colorimetric and optical sensing activity specifically towards the toxic Hg2+ ion. [ABSTRACT FROM AUTHOR]

A systematic study is currently demonstrated approach for approving the superior role of silver and palladium metallic particles in acting the role of mordant with acquiring the dyed cotton fabrics excellence in color fastness with additional functions of antimicrobial potentiality and UV-protection action. Whereas, samples were dyed with extract of red peanuts skin as natural textile colorant (RPN dye). The represented data revealed that, in absence of mordant, the samples treated with metal precursors prior to dyeing were exhibited with the excellent color strength, color fastness, antimicrobial action and UV-protection action. Color fastness (washing, rubbing and light fastness) was estimated to be in the range of very good–excellent. Sample pretreated with silver salt and dyed in the absence of mordant was graded with excellent UV-protection action (UPF 31.5, UVB T% 2.6% and UVB blocking percent 97.4%). Antimicrobial potency against E. coli, S. aureus and Candida albicans through inhibition zone and the reduction percent was approved to be in the range of excellence (93.01–99.51%) for the samples dyed in absence of mordant and pretreated with either silver or palladium precursors. [ABSTRACT FROM AUTHOR]

A systematic study is currently demonstrated approach for approving the superior role of silver and palladium metallic particles in acting the role of mordant with acquiring the dyed cotton fabrics excellence in color fastness with additional functions of antimicrobial potentiality and UV-protection action. Whereas, samples were dyed with extract of red peanuts skin as natural textile colorant (RPN dye). The represented data revealed that, in absence of mordant, the samples treated with metal precursors prior to dyeing were exhibited with the excellent color strength, color fastness, antimicrobial action and UV-protection action. Color fastness (washing, rubbing and light fastness) was estimated to be in the range of very good–excellent. Sample pretreated with silver salt and dyed in the absence of mordant was graded with excellent UV-protection action (UPF 31.5, UVB T% 2.6% and UVB blocking percent 97.4%). Antimicrobial potency against E. coli, S. aureus and Candida albicans through inhibition zone and the reduction percent was approved to be in the range of excellence (93.01–99.51%) for the samples dyed in absence of mordant and pretreated with either silver or palladium precursors. [ABSTRACT FROM AUTHOR]

The reactions of copper, silver and palladium salts with the homochiral ligands 3,3′-bis[(S,S)-4-isopropyl-2-oxazolyl]-4-chloro-2,2′-bipyridine (L1), 3,3′-bis[(S,S)-4-benzyl-2-oxazolyl]-4-chloro-2,2′-bipyridine (L2) and 2-[(S)-4-isopropyl-2-oxazolyl]quinoline (L3) yield three new chiral complexes: [Cu(L1)Br2] (1), [Ag(L2)(CH3CN)]·(BF4)·(CH3OH)0.17·(H2O)0.08 (2) and [Pd(L3)Cl2]·(CH3COCH3)0.5 (3), which have been characterized by single-crystal X-ray diffraction, IR spectroscopy, and elemental and thermogravimetric analyses. The complexes 1–3 display discrete mononuclear structures. Non-linear optical properties of complexes 1–3 were investigated. [ABSTRACT FROM AUTHOR]

Green nanoparticle (NPs) synthesis is eco-friendly, non-toxic, and the NPs have demonstrated improved biocompatibility for use in healthcare. This study evaluated the biogenic synthesis of AgNPs from the leaves of Cardamine hirsuta L. and their biological properties. The UV-Vis. spectra at 411 nm exhibited a distinct resonance spectrum for C-AgNPs produced from C. hirsuta L. FT-IR analysis exhibited the presence of functional groups of phyto-compounds of C. hirsuta responsible of silver salt reduction and capping agents of C-AgNPs. The microscopic-based study, such as HR-TEM analysis, showed that the particles were uniformly distributed, spherical, and ranged in size from 5.36 to 87.65 nm. EDX analysis confirmed a silver (Ag) content of 36.3% by weight, and XRD analysis exhibited the face-centred cubic (FCC) crystalline nature of C-AgNPs. DLS measured the mean particle size of 76.5 nm. The zeta potential was significant at −27.9 mV, and TGA analysis revealed that C-AgNPs had higher thermal stability. C-AgNPs demonstrated moderate antimicrobial activity against the tested pathogens. In addition, the anti-proliferative activity measured by the MTT assay on the Caco-2 cell line demonstrated decreased cell viability with increasing C-AgNPs dosage, with an IC50 concentration of 49.14 µg/mL. In addition, an Annexin-V/Propidium iodide flow cytometric study was utilized to evaluate the induction of apoptosis in cancer cells. Early and late apoptosis cell populations increased significantly compared to the untreated control. Therefore, green-synthesized C-AgNPs have significant antimicrobial and anti-proliferative abilities, making them intriguing options for future biomedical applications. [ABSTRACT FROM AUTHOR]

A chromatographic system based on in-tube SPME coupled to capillary LC-DAD has been used to study the synthesis of silver nanoparticles using polyphenols in different scenarios: excess of the reducing agent or of the silver salt, addition of the cationic surfactants, and thermal synthesis. The optimized synthesis conditions allowed to quantify the polyphenols used as reducing agents, such as Trolox and chlorogenic acid. Two chromatographic peaks with different absorption spectrum were monitored during the syntheses. Depending on the molar relationship, a linear relation between the area of the chromatographic peaks and the concentration of the silver or polyphenol was established. For stabilization of silver nanoparticles, different cationic surfactants were used allowing to evaluate the role of anion (chloride and bromide) and of the alkyl chain. The proposed methodology can be used to determine chlorogenic acid up to 3 mM with a detection limit of 34 μM at λ= 400 nm. Chlorogenic acid was determined in dietary products with successful results. Precision (RSD=10%) and recovery (97–100%) were also satisfactory. [ABSTRACT FROM AUTHOR]

With the aim of achieving bioorthogonal intracellular catalysis, a library of platinum(II) complexes was synthesized. Their non‐toxicity to living cells was demonstrated and their catalytic activity was evaluated on a cyclization reaction leading to a highly fluorescent coumarin. None of the platinum complexes showed any catalytic activity for coumarin synthesis. Still, we demonstrated that the silver salt AgSbF6 commonly used to 'activate' metal catalysts by removing a chloride is a very efficient catalyst for the studied intramolecular cyclization reaction. [ABSTRACT FROM AUTHOR]

Reported herein is the development of a novel method for activating thioglycosides without a glycosyl halide intermediate. This has been achieved through the use of a silver salt coupled with an acid additive and molecular iodine. The enhanced stereocontrol was achieved via the H‐bond mediated aglycone delivery (HAD) method, and the extended trisaccharide synthesis was achieved via iteration of deprotection and glycosylation steps. [ABSTRACT FROM AUTHOR]

A catalytic amount of CsI enables dual concurrent activation of poorly reactive perfluoroalkoxide and alkyl halides, especially alkyl chlorides, leading to the formation of diverse perfluoroalkoxylated organic compounds. Installation of perfluoroalkoxy groups by this methodology is cost-effective, circumventing the need for over-stoichiometric cesium or silver salts. This methodology also provides high functional group compatibility and tolerance of sterically hindered substrates. [ABSTRACT FROM AUTHOR]

An approach based on the use of a silver salt with an organic anion based on nicotinonitrile containing a tricyanobutadiene fragment was proposed for the quantitative fluorimetric determination of a number of anions and thiols, including glutathione and cysteine. [ABSTRACT FROM AUTHOR]

Phosphoranides comprising three phosphorus carbon bonds are scarcely represented in the literature. We now utilized tris(pentafluoroethyl)phosphane, P(C2F5)3, and cyanobis(pentafluoroethyl)phosphane, P(C2F5)2(CN), featuring electron withdrawing pentafluoroethyl groups, to synthesize such compounds. Metal fluorides MF (M=Ag, Cs) add to P(C2F5)3 yielding respective M[P(C2F5)3F] salts. Those M[P(C2F5)3F] subsequently suffer a loss of C2F4, furnishing M[P(C2F5)2F2]. The cesium salt decomposes instantaneously when warmed to rt, whereas the silver salt decomposes slowly over several days at rt. Treatment of Ag[P(C2F5)3F] with 2,2'‐bipyridine facilitated the isolation and structural characterization of [Ag(bipy){P(C2F5)3F}]. With P(C2F5)2(CN), AgF reacts under substitution of the cyano group yielding P(C2F5)2F, rather than phosphoranide formation. However, [K(18‐crown‐6)]F adds to P(C2F5)2(CN) furnishing [K(18‐crown‐6)][P(C2F5)2(CN)F]. Its structural characterization was successful, despite its tendency to undergo an exchange of substituents, yielding [K(18‐crown‐6)][P(C2F5)2F2] and presumably [K(18‐crown‐6)][P(C2F5)2(CN)2]. The latter forms an equilibrium with [K(18‐crown‐6)]CN and P(C2F5)2(CN) which lies well on side of the phosphane and cyanide salt. [ABSTRACT FROM AUTHOR]

In our previous study, quaternary fluoroalkyl phosphonium salt with iodine anion (PPICF-13) was synthesized as an antibacterial agent for PC, but it would dye PC to be brown during processing because of the oxidation of the iodine. With the aim to eliminate the dyeing problem, three quaternary fluoroalkyl phosphonium salts (PPCF) with trifluoroacetate (TFA-PPCF-13), tetrafluoroborate (FB-PPCF-13), and trifluoromethanesulfonate (TFMS-PPCF-13) were synthesized in the research described here through anion exchange reactions between PPICF-13 with the relative silver salts. After evaluation of their antibacterial activity and thermal stability, FB-PPCF-13 was chosen to prepare antibacterial PC through injection processing. The influence of FB-PPCF-13 concentration on the mechanical properties, thermodynamic properties, light transmittance, appearance, and antibacterial activity of the antibacterial PC was investigated. The results showed that incorporation of FB-PPCF-13 had no negative influence on the mechanical properties of PC, but could reduce Tg and increase the MFI due to the plasticization effect of FB-PPCF-13. When the concentration of FB-PPCF-13 was 2 wt.% or more, the resulting antibacterial PC could have strong antibacterial activity no matter before or after being aged. Though FB-PPCF-13 reduced the light transmittance of PC, it did not influence the color scheme of dyed PC products. [ABSTRACT FROM AUTHOR]

Propargyl ureas can lead to a range of possible heterocyclic compounds, mainly depending on the employed catalyst. Silver salts are known to promote the N-5-exo-dig cyclization mode to imidazolidinone derivatives. Conversely, a versatile and stereoselective O-5-exo-dig cyclization of propargyl ureas to 2-aminooxazolines by Ag(I) catalysis is here disclosed. Good to excellent yields and complete stereoselectivity of the external double bond have been achieved under milder reaction conditions (50-60 °C). A one-pot protocol starting from the corresponding propargylic amines and isocyanates has been developed as well. N,N'-Dipropargyl ureas underwent a uncommon O-5-exo-dig/N-5-endo-dig double cyclization sequence. Finally, insights into the tautomeric equilibrium of 2-aminooxazoles and on their relative reactivity are provided. [ABSTRACT FROM AUTHOR]

Our research centers on structural, biological, and electronic properties of N-heterocyclic carbene salts and their silver acetate-based complexes. After theoretical calculations, compounds were synthesized. In the DFT studies, functional of B3LYP was used with the basis set of 6-31++G and LanL2DZ for salts and complexes, respectively. The most stable structures were calculated and non-covalent interactions evaluated. Electronic parameters were checked while calculating their HOMO and LUMO energies so that their biological potential can be evaluated. Density of states were studied to check the electronic densities. Among all compounds, 3 was considered the best with energy gap of 0.121 eV. As all eight compounds have very reasonable HOMO-LUMO energy gaps they were considered feasible to synthesize and have strong biological potentials. Compounds were characterized by FT-IR and NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Facilitated transport membranes containing silver ions have attracted much attention thanks to their high performance in olefin/paraffin separation. However, the poor long-term stability of such membranes remains a drawback that must be overcome to enable their practical use. In this work, silver ions were incorporated as ion complexes in the Pebax®2533 matrix to increase their stability as a function of time. Two complexing agents were evaluated: ammonia and 15-crown-5-ether. Membranes of Pebax®2533/Ag(NH3)2OH and Pebax®2533/[Ag(15-crown-5-ether)]BF4 maintained stable selectivity for more than thirty days of observation without compromising permeability. Although complexation decreases the performance of silver compared to free ions, it significantly increases the long-term performance in ethylene/ethane separation. the complexing agents weaken the intensity and strength of Ag+/ethylene-π complexation, but prevent the reduction of Ag(I) to Ag(0). In long-term single gas permeation tests, the Pebax®2533/Ag(NH3)2OH membrane showed selectivity in the range of 12.3 to 9 for 39 days, while the Pebax®2533/[Ag(15crown-5-ether)]BF4 membrane showed selectivity around 9 for 30 days. Mixed gas permeation studies allowed to identify conditions to maintain the separation performance above the upper bound for more than 40 days, under continuous membranes exposure to mixed gases. Increased stability compared to membranes reported in the literature was achieved. [ABSTRACT FROM AUTHOR]

Saline soil or water can highly affect plant physiological and biochemical responses including general disruption in the nutritional status of plants, osmotic stress, and ion-specific toxicity The rapid development and potential release of engineered nanoparticles (ENPs) have raised considerable concerns due to the unique properties of nanomaterials. Spinach is considered a model plant in hydroponic system production and is of research interest all over the world. In this study, we aim to study the physiological responses of spinach under different concentrations of both silver nanoparticles and salt stress. Spinach seedlings were exposed to 16 treatments asthreesalinity concentrations (4.0, 6.0, and 10.0 dS.m-1),three silver nanoparticles concentrations (20, 40, 60 ppm), nine treatments as combination of salinity and silver nanoparticles and control.Relative water content (RWC), stomatal conductance (gs), chlorophyll content index (CCI),), dry weights (DW), leaf area (LA), and specific leaf area (SLA) of 41 days old spinach seedlings were examined and recorded for 6 weeks. The application of Silver nanoparticles had affected plant growth and altered many plant physiological responses. We concluded that silver nanoparticles might have positive effects on the physiological parameters but only under non-saline stress. However, it negatively impacts plants when it was added under saline conditions. [ABSTRACT FROM AUTHOR]

Cascade reactions provide a straightforward access to many valuable compounds and reduce considerably the number of steps of a synthetic sequence. Among the domino and multicomponent processes that involve alkynes, the cascade reaction between alkynoic acids and C-, N-, O- and S-aminonucleophiles stands out as a particularly powerful tool for the one-pot construction of libraries of nitrogen-containing heterocyclic compounds with scaffold diversity and molecular complexity. This reaction, based on an initial metal-catalyzed cycloisomerization that generates an alkylidene lactone intermediate, was originally catalyzed by gold(I) catalysts, along with silver salts or Brönsted acid additives, but other alternative metal catalysts have emerged in the last decade as well as different reaction media. This review examines the existing literature on the topic of metal-catalyzed cascade reactions of acetylenic acids and dinucleophiles and discusses aspects concerning substrate/catalyst ratio for every catalyst system, nature of the aminonucleophile involved and substrate scope. In addition, alternative solvents are also considered, and an insight into the pathway of the reaction and possible intermediates is also provided. [ABSTRACT FROM AUTHOR]

Silver nanodal was synthesized on orthodontic braces using silver nitrate salts as an electrochemical method. The synthesized Ag nanobranch were characterized by UV-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Antibacterial microbial performance of Lactobacillus salivarius analyzed with electrochemically synthesized silver nanobranch on orthodontic brackets. The specific antibacterial properties of all the composites showed specific antibacterial effects or antiadherence, independently of the amount of silver nanobranch deposited, likely due to the differences in the bacterial cell wall structures. As a result, the brackets, which are very important for orthodontics, showed a good antibacterial performance with the nanostructures obtained by electrochemically coated with Ag, which is known to have antibacterial properties. [ABSTRACT FROM AUTHOR]

The search for new anticancer drugs based on biogenic metals, which have weaker side effects compared to platinum-based drugs, remains an urgent task in medicinal chemistry. Titanocene dichloride, a coordination compound of fully biocompatible titanium, has failed in pre-clinical trials but continues to attract the attention of researchers as a structural framework for the development of new cytotoxic compounds. In this study, a series of titanocene (IV) carboxylate complexes, both new and those known from the literature, was synthesized, and their structures were confirmed by a complex of physicochemical methods and X-ray diffraction analysis (including one previously unknown structure based on perfluorinated benzoic acid). The comprehensive comparison of three approaches for the synthesis of titanocene derivatives known from the literature (the nucleophilic substitution of chloride anions of titanocene dichloride with sodium and silver salts of carboxylic acids as well as the reaction of dimethyltitanocene with carboxylic acids themselves) made it possible to optimize these methods to obtain higher yields of individual target compounds, generalize the advantages and disadvantages of these techniques, and determine the substrate frames of each method. The redox potentials of all obtained titanocene derivatives were determined by cyclic voltammetry. The relationship between the structure of ligands, the reduction potentials of titanocene (IV), and their relative stability in redox processes, as obtained in this work, can be used for the design and synthesis of new effective cytotoxic titanocene complexes. The study of the stability of the carboxylate-containing derivatives of titanocene obtained in the work in aqueous media showed that they were more resistant to hydrolysis than titanocene dichloride. Preliminary tests of the cytotoxicity of the synthesised titanocene dicarboxilates on MCF7 and MCF7-10A cell lines demonstrated an IC50 ≥ 100 μM for all the obtained compounds. [ABSTRACT FROM AUTHOR]

Waveguide–plasmon polaritons sustained in metallic photonic crystal slabs show fascinating properties, such as narrow bandwidth and ultrafast dynamics crucial for biosensing, light emitting, and ultrafast switching. However, the patterning of metallic photonic crystals using electron beam lithography is challenging in terms of high efficiency, large area coverage, and cost control. This paper describes a controllable patterning technique for the fabrication of an Ag grating structure on an indium–tin oxide (ITO) slab that enables strong photon–plasmon interaction to obtain waveguide–plasmon polaritons. The Ag grating consisting of self-assembled silver nanoparticles (NPs) exhibits polarization-independent properties for the excitation of the hybrid waveguide–plasmon mode. The Ag NP grating can also be annealed at high temperature to form a continuous nanoline grating that supports the hybrid waveguide–plasmon mode only under transverse magnetic (TM) polarization. We tuned the morphology and the periodicity of the Ag grating through the concentration of silver salt and the photoresist template, respectively, to manipulate the strong coupling between the plasmon and the waveguide modes of different orders. [ABSTRACT FROM AUTHOR]

This manuscript describes the synthesis and coinage metal complexes of pyridine appended 1,2,3-triazolyl-phosphine [2-{(C6H4N)(C2(PPh2)N3C6H5)}] (1), photophysical studies and their catalytic application. The reactions of 1 with copper salts afforded dimeric complexes [{Cu(μ2-X)}2{2-(C6H4N)(C2(PPh2)N3C6H5)}2] (2, X = Cl; 3, X = Br; and 4, X = I). The crystal structure indicates that the Cu⋯Cu distance in 4 (2.694 Å) is significantly shorter than that in complexes 3 (3.0387 Å) and 2 (3.104 Å), indicating strong cuprophilic interactions which is also supported by NBO calculations, signifying the involvement of 3dz2 orbitals from each Cu atom contributing to the bonding interaction. The fluorescence studies on complexes 2–4 carried out in the solid state showed broad emission bands around 560 nm on excitation at λex = 420 nm. Complex 4 on treatment with two equivalents of 1,10-phenanthroline yielded a mononuclear complex 5 which showed almost complete quenching of fluorescence in the solid state, clearly indicating that the emissive properties of 4 are mainly due to the Cu⋯Cu interaction, along with (M + X)LCT. The reactions of 1 with silver salts led to the isolation of dimeric complexes [{Ag(μ2-X)}2{2-(C6H4N)(C2(PPh2)N3C6H5)}2] (6, X = Cl; 7, X = Br; and 8, X = I) in good yield. The reaction between 1 and [AuCl(SMe2)] yielded [{AuCl}{2-(C6H4N)(C2(PPh2)N3C6H5)}] (9). The molecular structures of 2–5 and 7–9 were confirmed by single crystal X-ray analysis. The complex 4 is found to be an excellent catalyst for C–O coupling under mild conditions. [ABSTRACT FROM AUTHOR]

The new mono dibenzo[b,f]-azepinyl substituted P-alkene ligands 7–9, 20, and 21 were used to synthesize monomeric and dimeric Cu(I) complexes by using metal to ligand ratios of 2 : 1 and 1 : 1, respectively. With the super-bulky tris dibenzo[b,f]-azepinyl substituted P-alkenes 21, only monomers form with a 1 : 1 stoichiometry. Cationic complexes were obtained either by employing [Cu(OTf)]2·C6H6 as the starting material, or by chloride abstractions from the monomeric chlorido complexes with NaB(ArF)4 or TlBF4, whereas with silver salts only Ag(I)-P-alkene complexes were isolated by transmetallation. Chloride abstraction with NaB(ArF)4 gave the 14 ve cationic complex 18, which shows no alkene coordination and a bent coordination geometry due to the steric pressure exerted by the ligand. The buried volumes of the ligands (calculated from X-ray diffraction data) increase in the order 8 < 7 < 9 < 20 < 21 with the last displaying a staggering Vbur of 60.6% (the crystallographic Tolman angle in copper complex 23 amounts to 229°). The bulkiest ligand (21) allowed us to isolate and structurally characterize rare examples of 14 ve Cu(I) complexes, namely the neutral chloride 23 and, after salt metathesis with NaB(ArF)4, the chlorido bridged dinuclear cation 26 exhibiting short Cu–Cl bonds. [ABSTRACT FROM AUTHOR]

Pairing cations with weakly coordinating anions (WCAs) often renders them highly Lewis‐acidic and extremely reactive. Although these features are often desirable, excessive reactivity of a cation may lead to decomposition of solvents or WCAs, hindering isolation, storage and practical use of such species. In an attempt to mitigate the problem, we introduce a series of readily available novel Co(II)‐WCA salts with the metal center stabilized by weakly bound ligands: SO2, halogenated acetonitriles and nitromethane with comprehensive characterization including structural, magnetic and spectral (IR) properties as well as thermal stability assessment. The use of these simple yet rarely encountered ligands yields mostly stable and highly Lewis‐acidic complexes, in some cases comparable to SbF5 according to calculated Fluoride Ion Affinities. Highly acidic character of the species is also reflected in observed reactivity. Since the most convenient route towards the Co(II) complexes leads through silver salts, the results are complemented with characterization of a series of novel Ag(I) complexes with abovementioned ligands. Experimental part is backed with DFT calculations which gives insight into the structure and energetics of presented Co(II) complexes and shows that Co(II) center is available for substrates like olefins. This makes them good candidates for catalysts in reactions requiring the presence of Lewis acids. [ABSTRACT FROM AUTHOR]

The reaction of [NiArBr(PPh3)2] with AgBF4 brings about the abstraction of both the halide and phosphine from the nickel center by silver. When the reaction is carried out in CH2Cl2/toluene a mixture of the cationic aquo derivatives [NiAr(H2O)(PPh3)2]BF4 (2) and [NiAr(H2O)2(PPh3)]BF4 (3) is formed, along with AgBr and [Ag(PPh3)n]BF4. When the same reaction is carried out in acetone as the solvent, it leads to the completely different complex [NiAr(κ2-O, O–MeC(O)CH2C(OH)Me2)(PPh3)] (5), bearing a chelating ligand formed by the aldol self-condensation of acetone. Phosphine abstraction by silver is less favorable for the analogous palladium(II) complexes and only occurs if a large excess of AgBF4 is used. Thus, silver salts can be safely used as halide scavengers for palladium derivatives. However, the generation of cationic Ni complexes from neutral precursors by halide extraction with a silver salt may produce naked species, different than those expected, and highly reactive in certain media. [ABSTRACT FROM AUTHOR]

The objectives of the present study were to examine the influence of visible light photons on photoreduction of the silver nanoparticles (AgNPs), detect optoelectronic feedback, and observe the antimicrobial activity. For this purpose, an optoelectronic device was designed and successfully tested. The finding shows that identical nanocomplexes with silver salt express various responses to the LEDs with different wavelengths by scattering different portions of light. It is the first time to discuss the effect of visible light photons on nano-sized particles in detail based on the quantitative optical/voltage analysis. The photoreduction of the AgNPs is in good agreement with photon energy and the AgNPs occur in nanocomplex in a wavelength versus time-dependent manner. The blue LED having photon energy 7.04 eV reduces the average size of AgNPs down to the range 4–6 nm in 12 min, while AgNPs obtained under influence of green (6.11 eV) and red (5.04 eV) LEDs have average sizes 6–8 nm and 12–14 nm respectively. The successful synthesis of AgNPs was additionally examined using UV–Vis, SEM, XPS, XRD, FTIR, and TEM techniques. AgNPs proved for antimicrobial activity against Escherichia coli 25922, Enterococcus faecalis 29212, Pseudomonas aeruginosa 27853, and Candida albicans 10231 at four different concentrations. The antibacterial test for all selected bacteria showed that AgNPs which have an average size of 4-6 nm synthesized by blue LED revealed the largest inhibition zone around 16–11 mm, while the antifungal test shows that the maximum inhibition zone was exposed by AgNPs which have an average size of 6–8 nm synthesized by red LED. [ABSTRACT FROM AUTHOR]

The activation of carbon−hydrogen bonds is considered as one of the most attractive techniques in synthetic organic chemistry because it bears the potential to shorten synthetic routes as well as to produce complementary product scopes compared to traditional synthetic strategies. However, many current methods employ silver salts as additives, leading to stoichiometric metal waste and thereby preventing the full potential of C−H activation to be exploited. Therefore, the development of silver‐free protocols has recently received increasing attention. Mechanistically, silver can serve various roles in C−H activation and thus, avoiding the use of silver requires different approaches based on the role it serves in a given process. In this Review, we present the comparison of silver‐based and silver‐free methods. Focusing on the strategic approaches to develop silver‐free C−H activation, we provide the reader with the means to develop sustainable methods for C−H activation. [ABSTRACT FROM AUTHOR]

A simple silver salt (AgSbF6)‐catalyzed aminophosphonylation and Strecker reaction have been developed and successfully applied to a wide range of substrates (>55 substrates). This solvent‐, ligand‐, and base‐free one‐pot three‐component protocol operates effectively at room temperature to provide diversified α‐aminophosphonates and α‐aminonitriles, which gave access to the respective α‐amino amides. Importantly, the present catalyst system is also capable to produce the rarely reported and biologically relevant aminophosphonates (having anti‐leishmanial activity). Further, mechanistic studies reveal that the present phosphonylation protocol follows a radical pathway. [ABSTRACT FROM AUTHOR]

The effect of soft UV radiation (365 nm) on self-assembly in an aqueous l-cysteine-silver solution (CSS) and hydrogels based on it has been studied. It was determined that CSSs based on various silver salts (silver nitrate, acetate, and nitrite) exhibit different photosensitivities, and their color can change up to dark brown under UV irradiation. The color change of CSSs is a result of the plasmon resonance of the free electrons on the surface of the obtained silver nanoparticles (Ag NPs). Self-assembly in CSSs under UV irradiation proceeded at a much faster rate compared to the case of irradiation with visible light. When the duration (dose) of UV irradiation was increased, the self-assembly mechanism in CSSs with the participation of silver ions was replaced by the mechanism with the participation of the obtained silver nanoparticles. [ABSTRACT FROM AUTHOR]

The synthesis and solid-state characterisation of the heterobimetallic rhodium(III)/silver(I) complex [Rh(2,2′-biphenyl)(CxP2)Cl]⊃Ag+ is described, where CxP2 is a trans-spanning calix[4]arene-based diphosphine and the silver cation is datively bound to the chloride ligand within the cavity of the macrocycle. [ABSTRACT FROM AUTHOR]

An antimicrobial polyacrylic silver salt (freshly prepared, stored for one year and model-aged) was studied by physical–chemical techniques for nanoparticle detection. In all cases, this salt represents a composite of radical-enriched macromolecules and silver(0) nanoparticles. As time passed, the initial small spherical nanoparticles were converted into larger non-spherical silver nanoparticles. The initial highly water-soluble antimicrobial solid nanocomposite almost loses its solubility in water and cannot be used as an antimicrobial agent. Unlike insoluble solid silver polyacrylate, its freshly prepared aqueous solution retains a liquid-phase consistency after one year as well as pronounced antimicrobial properties. The mechanism of these spontaneous and model-simulated processes was proposed. These results have attracted attention for officinal biomedicinal silver salts as complex radical-enriched nanocomposite substances; they also indicate contrasting effects of silver polymeric salt storing in solid and solution forms that dramatically influence antimicrobial activity. [ABSTRACT FROM AUTHOR]

In this report we demonstrate the use of Citrus japonica (CJ) leaf extract for the first time as biological liquid to work as capping as well as reducing agent for synthesizing extremely stable silver nanoparticles (AgNPs) from its precursor silver salt. Different parameters such as pH, speed of reaction, silver salt concentrations and leaf extract were optimized for the formation of CJ-AgNPs. CJ-AgNPs were then characterized through techniques like Ultra-violet visible (UV–Vis) spectroscopy, Fourier transform infra-red (FTIR) spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), Zeta-potential analysis (ZPA) and dynamic light scattering (DLS). As-formed CJ-AgNPs were verified as highly sensitive, extremely selective, stable, economical, eco-friendly and rapidly responsive colorimetric sensor for Hg2+ detection based on color change in solution from yellow to brownish. The dynamic range of developed sensor worked linearly in the range of 0.3–7.3 µM with R2 value of 0.999 and limit of (LOD) and limit of quantification (LOQ) as 0.09 µM and 0.30 µM respectively. The sensor demonstrated negligible interference under the influence of ions like Mg2+, Zn2+, Cu2+, Co2+, Pb2+, Cd2+ and Fe2+ and corresponding anions. The developed sensor was successfully applied to detect Hg2+ at low level in some real water samples. [ABSTRACT FROM AUTHOR]

This study was carried out on six adult red kangaroos of both sexes. To determine the location of the oligodendrocytes (OLGs) of the hippocampus (Hip) and corpus callosum (CC), the method of impregnation of the neuroglia with silver salts was applied. The iron distribution in the OLGs was determined by the histochemical method. The Nissl method was used to determine the location of the brain structure and to analyze the number of OLGs. In the Hip, these cells are located one beside another, mainly in blood vessels and neurons; in the neocortex (NC), they are located in layers I–VI; and in the CC, they are arranged in characteristic rows and accompany both nerve fibers and blood vessels. The analysis of the results obtained by the chosen methods in the Hip, NC, and CC in males and females did not show statistically significant differences in the distribution and location of the red kangaroo OLGs. The involvement of these cells is a physiological process that proceeds in a similar manner throughout the life of individuals and actively influences the metabolism of neurons and myelin. [ABSTRACT FROM AUTHOR]

Polysaccharide-based composites embedding silver nanoparticles (AgNPs) represent a promising alternative to common antimicrobial materials because of the effective, broad-spectrum biocidal properties of AgNPs combined with the biocompatibility and environmental safety of the naturally occurring polymeric component. In this work, AgNPs stabilized with alginate chains (Alg@AgNPs) were successfully synthesized in situ within the polysaccharide solution through a wet chemical approach carried out at different concentrations of the silver salt precursor. Once obtained, the aqueous suspensions were electrospun to prepare non-woven membranes, showing a homogeneous nanostructured texture (with fiber diameter between 100 and 150 nm), which was found to be influenced by the size (between 20 and 35 nm) of the embedded metal nanoparticles. The biocidal potential of the nanocomposite mats was preliminarily tested against Gram-negative E. coli. The results showed that the antimicrobial response of the investigated samples occurred within a day of incubation and can be observed for AgNPs content in the polysaccharide fibers far below the nanomolar regime. [ABSTRACT FROM AUTHOR]

The enantioselective 1,3-dipolar cycloaddition between imino esters and (Z)-nitroalkenes bearing a masked amino group in the β-position was studied using several chiral ligands and silver salts. The optimized reaction conditions were directly applied to the study of the scope of the reaction. The determination of the absolute configuration was evaluated using NMR experiments and electronic circular dichroism (ECD). The reduction and hydrolysis of both groups was performed to generate in an excellent enantiomeric ratio the corresponding cis-2,3-diaminoprolinate. [ABSTRACT FROM AUTHOR]