X-ray crystal structure of [L 2Ag3]+[OTf]−·5C6D6: a monoanionic bisphosphinimine ligand supported trisilver complex

The compound bis{μ3-2,5-bis[N-(4-isopropylphenyl)-P,P-diphenylphosphorimidoyl]pyrrol-1-ido-κ3 N:N′:N′′}trisilver(I) trifluoromethanesulfonate deuterated benzene pentasolvate, [Ag3(C46H44N3P2)2](CF3O3S)·5C6D6, (I), was synthesized from two equivalents of NaL [L = 2,5-(4- i PrC6H4N=PPh2)C4H2N] and three equivalents of AgOTf (OTf = OSO2CF3). High-quality crystals of (I) formed with five deuterated benzene solvent molecules in the asymmetric unit. Notably, the bond lengths and angles between the three silver atoms are markedly different, unlike in most other reported trisilver complexes that tend to form three equivalent metal centers. Additionally, to the best of our knowledge, this is the first report of a trisilver complex with six nitrogen donors from two bisphosphinimine ligands.

Impact of Metals on (Star)Dust Chemistry: A Laboratory Astrophysics Approach

Laboratory experiments are essential in exploring the mechanisms involved in stardust formation. One key question is how a metal is incorporated into dust for an environment rich in elements involved in stardust formation (C, H, O, Si). To address experimentally this question we have used a radiofrequency cold plasma reactor in which cyclic organosilicon dust formation is observed. Metallic (silver) atoms were injected in the plasma during the dust nucleation phase to study their incorporation in the dust. The experiments show formation of silver nanoparticles (~15 nm) under conditions in which organosilicon dust of size 200 nm or less is grown. The presence of AgSiO bonds, revealed by infrared spectroscopy, suggests the presence of junctions between the metallic nanoparticles and the organosilicon dust. Even after annealing we could not conclude on the formation of silver silicates, emphasizing that most of silver is included in the metallic nanoparticles. The molecular analysis performed by laser mass spectrometry exhibits a complex chemistry leading to a variety of molecules including large hydrocarbons and organometallic species. In order to gain insights into the involved chemical molecular pathways, the reactivity of silver atoms/ions with acetylene was studied in a laser vaporization source. Key organometallic species, AgnC2Hm (n = 1–3; m = 0–2), were identified and their structures and energetic data computed using density functional theory. This allows us to propose that molecular Ag–C seeds promote the formation of Ag clusters but also catalyze hydrocarbon growth. Throughout the article, we show how the developed methodology can be used to characterize the incorporation of metal atoms both in the molecular and dust phases. The presence of silver species in the plasma was motivated by objectives finding their application in other research fields than astrochemistry. Still, the reported methodology is a demonstration laying down the ground for future studies on metals of astrophysical interest, such as iron.

Atomistic Insights into Aluminum Doping Effect on Surface Roughness of Deposited Ultra-Thin Silver Films

Ultra-thin and continuous metallic silver films are attracting growing interest due to the applications in flexible transparent conducting electrodes. The surface morphology and structure of silver film are very important for its electrical resistivity and optical loss. Therefore, roughness control is essential for the production of ultra-thin metallic electrode film. We have investigated the effect of aluminum doping on the improvement of surface morphology of ultra-thin silver films using molecular dynamics simulations. Al-doped silver films showed smaller surface roughness than pure silver films at various substrate temperatures. When the temperature of the substrate was 600 K, the roughness of Al-doped silver film first decreased, and then increased with the increase of the incident velocity of silver atoms. Silver atoms were more likely to agglomerate on the surface of the substrate after adding aluminum atoms, as aluminum dopants promoted the immobilization of silver atoms on SiO2 substrate due to the anchoring effect. The smoother surface could be attributable to the reduced mean free path of silver due to the cage effect by the aluminum dopant.

The spatial organization of trace silver atoms on a DNA template

This review summarized the direct link between the silver atom organization on the DNA secondary structure and the performance of AgNCs, providing an all-round support for understanding the origin of DNA/AgNCs.

Упругие свойства нанокристаллических кубических сульфидов Ag-=SUB=-2-=/SUB=-S и ZnS

The structure of Ag2S/ZnS heteronanostructures is considered taking into account the anisotropy of the elastic properties of Ag2S and ZnS sulfides. It is shown that a large amount of cubic zinc sulfide stabilizes the cubic structure of beta-Ag2S argentite at 300 K during the deposition of Ag2S/ZnS heteronanostructures from colloidal solutions. The elastic stiffness constants c11, c12, and c44 of cubic argentite beta-Ag2S and sphalerite ZnS are estimated at a temperature of 300 K. Physically possible variants of the arrangement of silver atoms at fixed crystallographic positions of cubic argentite are determined. It is shown that the energetically most favorable is the formation of beta-Ag2S heterostructures, in which the interface is formed by the (hk0) plane of ZnS sphalerite and the (hk 0.5) plane of beta-Ag2S argentite. Calculation of the universal criterion for the anisotropy of the elastic properties of cubic argentite beta-Ag2S and sphalerite ZnS showed that the studied silver and zinc sulfides are elastically anisotropic.

Modification of Pyrolyzed Polyacrylonitrile with Silver Atoms

Recently, the search for new materials for nanoelectronics has attracted the interest of scientists. New materials, which are metal-polymer nanocomposites, can be used in modern electronics. The paper presents the possibility and mechanisms for the formation of a metal composite based on single-layer and two-layer pyrolyzed polyacrylonitrile when interacting with silver atoms. The results of the silver atom adsorption on the polymer surface are described, the possibility of filling the interlayer space with metal atoms is shown, and geometric and electron-energy characteristics are established. Theoretical calculations were performed using a molecular cluster model using a non-empirical method in the STO basis. The structure and electron-energy state of a metal-carbon nanocomposite based on pyrolyzed polyacrylonitrile with silver atoms are studied. It was found that the silver atom is adsorbed on the surface of PPAN, and the adsorption process is almost independent of the selected adsorption center. The introduction of metal atoms into the interplanar space of PPAN causes the initially planar monolayers of PPAN to bend, while the structure retains its stability. It was found that the presence of metal atoms in the PPAN structure causes a change in the band gap, which leads to a change in the conductive properties of the resulting nanocomposite.

Dinuclear Silver(I) Nitrate Complexes with Bridging Bisphosphinomethanes: Argentophilicity and Luminescence

Two silver nitrate complexes with bisphosphines were obtained and characterized: [Ag(dcypm)]2(NO3)2 (1; dcypm = bis(dicyclohexylphosphino)methane) and [Ag(dppm)]2(Me2PzH)n(NO3)2 (n = 1, 2a; n = 2, 2b; dppm = bis(diphenylphosphino)methane, Me2PzH = 3,5-dimethylpyrazole). The steric repulsions of bulky cyclohexyl substituents prevent additional ligand coordination to the silver atoms in 1. Compounds obtained feature the bimetallic eight-member cyclic core [AgPCP]2. The intramolecular argenthophilic interaction (d(Ag···Ag) = 2.981 Å) was observed in complex 1. In contrast, the coordination of pyrazole led to the elongation of Ag···Ag distance to 3.218(1) Å in 2a and 3.520 Å in 2b. Complexes 1 and 2a possess phosphorescence both in the solution and solid state. Time-dependent density-functional theory (TD-DFT) calculations demonstrate the origin of their different emission profile. In the case of 1, upon excitation, the electron leaves the Ag–P bonding orbital and locates on the intramolecular Ag···Ag bond (metal-centered character). Complex 2a at room temperature exhibits a phosphorescence originating from the 3(M + LP+N)LPhCT state. At 77 K, the photoluminescence spectrum of complex 2a shows two bands of two different characters: 3(M + LP+N)LPhCT and 3LCPh transitions. The contribution of Ag atoms to the excited state in both complexes 2a and 2b decreased relative to 1 in agreement with the structural changes caused by pyrazole coordination.